GB2581784A

GB2581784A - Battery management for a fluid analysis system

Info

Publication number: GB2581784A
Application number: GB1902418.1A
Authority: GB
Inventors: Zhang Zhiyong
Original assignee: Duvas Technologies Ltd
Current assignee: Duvas Technologies Ltd
Priority date: 2019-02-22
Filing date: 2019-02-22
Publication date: 2020-09-02
Anticipated expiration: 2039-02-22
Also published as: GB2581784B; GB201902418D0

Abstract

A battery management system 300 is arranged to receive electric power from a plurality of batteries 102a, 102b and to supply power to a load 308 from one amongst the plurality of batteries 102a, 102b at a time. The system monitors energy output from each battery 102a, 102b to determine the energy state of the battery 102a, 102b and determine whether it has a valid state. A first one of the batteries 102a may be assigned a high priority status and is preferentially used to supply power to the load 308 as long as it has a valid state. If the first battery 102a falls into a battery empty state, then power supply is switched to a second battery 102b having a valid state until the first battery 102a has a valid state. When a new battery is inserted, its voltage must be above a particular threshold before it is assigned to a valid state, otherwise it is assigned an invalid state. The particular threshold may be above 50% of maximum battery voltage. The battery empty state may be at 10% of maximum battery voltage. The system is suitable for supplying a fluid analytics system under the ATEX regulations and allows hot swapping of supplies.

Description

BATTERY MANAGEMENT FOR A FLUID ANALYSIS SYSTEM

FIELD

The invention relates to the management of batteries. Particularly, but not exclusively, the invention relates to a battery management system.

BACKGROUND

In environments where long and continued monitoring of potentially explosive gases is required, systems for determining the presence of such compounds in the environment require long and continued operation, often without interruption.

It is therefore necessary for the supply of electrical power to these systems to be uninterrupted as any drop in operation time could be dangerous and have grave consequences for those in that environment. That is to say, it is necessary for "hot swapping" to take place between the batteries supplying electrical power to the monitoring systems.

One solution to the requirement for hot swapping is disclosed in US6259171B1 which relates to a system which adopts a spare battery to supply power during the hot swap between the two battery sources. Another arrangement is described in US6153947 which discloses a dual feed hot swap battery plant controller.

In environments where explosive gases are being monitored the monitoring systems must meet the requirements of the AlEX regulations. The solutions provided by US6259171B1 and US6153947 do not meet the requirements of the ATEX regulations.

Aspects and embodiments were conceived with the above in mind.

SUMMARY

Aspects relate to battery management systems for fluid analysis systems. Such fluid analysis systems may be suitable for deployment in an explosive atmosphere (ATEX) regulated environment. To achieve this target, the comprehensive battery monitoring and protection solutions are designed, including: battery over-discharge protection (UVP), battery discharge overcurrent protection (OCP), load Short-Circuit Detection (SCP), battery overvoltage or surge protection, battery short-circuit protection, fuel gauge, hot swap, battery performance statistics analysis (PSS).

Viewed from a first aspect there is provided a battery management system for a fluid analytics system arranged to receive an electric power supply from one of a plurality of batteries, the system configured to monitor energy output from each of the plurality of batteries to determine the energy state of each of the plurality of batteries; and further configured to, based on the determined energy state and the priority, select one of the plurality of batteries to provide a supply of electrical power to the fluid analytics system.

The system in accordance with the first aspect monitors battery output to determine the energy provided by each battery and selects the battery to supply power to the fluid analytics system based on the determination.

At least one of the plurality of batteries may be assigned a high priority status and, responsive to the determination that the at least one batter has a valid energy state, the system may be configured to select the at least one battery to supply electrical power to the fluid analytics system.

The system may be further configured to determine that the at least one battery with a high priority status has an empty energy state and, responsive to the determination, switch the supply of electrical power from the battery with a high priority status to a second battery until the system determines the first battery has a valid energy state.

The system may be configured to determine the at least one of a plurality of batteries is a recently inserted battery and further configured to determine the energy state of the recently inserted battery.

A recently inserted battery is a battery which is inserted into the battery management system at the first time or has been used to replace a battery which was previously removed due it its invalid energy state.

The system may be configured to determine a battery valid energy state or a battery invalid 10 energy state for a recently inserted battery.

The system may be configured to reject the supply of power from a recently inserted battery for which the system determines a battery invalid energy state.

Viewed from a further aspect, there is provided a battery management system for a fluid analytics system arranged to receive an electrical power supply from a first one of a plurality of batteries, the system configured to predict a battery empty state by monitoring battery output from the first one of the plurality of batteries supplying electrical power to the fluid analytics system; and responsive to the prediction of a battery empty state, the system is further configured to switch the supply of electrical power from the first one of the plurality of batteries to a second one of the plurality of batteries.

A system in accordance with the first aspect may switch the supply of electrical power from a first battery to a second battery without interrupting the operation of a fluid analysis system. Furthermore, after replacing the first empty one of the plurality of batteries, the system may be configured to automatically switch the supply of electrical power from the second one of the plurality of batteries to the first one of the plurality of batteries, without interrupting the operation of a fluid analysis system.

A battery management system in accordance with the first aspect enables the prediction of a battery empty state and the automatic switching of batteries when it is determined that a battery is about to go into an empty state. A completely empty state of battery is dangerous in a fluid analysis system, particularly one working in an explosive atmosphere environment as they can cause failure in the system and damage batteries. Particularly for the automatic switching with a power supply priority scheme, the very high frequent and continuous swapping between two battery power supplies might be caused since the output voltage of a nearly empty battery with a high power supply priority significantly and immediately recovers when it is disconnected with a load, then the output voltage of that nearly empty battery significantly descend when it is reconnected with that load immediately again. This kind of very high frequent and continuous swapping between two battery power supplies will cause the repeated inrush current to batteries and fluid analytics system. Therefore, activating and maintaining the battery empty state before the battery is completely empty means that the system and the batteries will not be damaged by the battery output voltage recovery and repeated inrush current which take place when a battery is disconnected and approaching an empty state.

A new concept of battery valid energy state or capacity is introduced to solve the issue of the very high frequent and continuous swapping when the automatic swap occurs, which is caused by the output voltage recovery of a disconnected and nearly empty battery with a power supply priority. The output voltage threshold of valid battery energy capacity is defined as the enough level of output voltage sufficient to separate a nearly empty battery and a battery with enough energy. The key idea is that any battery is a valid power source only if the battery output voltage is above the defined output voltage threshold of battery valid energy capacity or state when that battery is recently inserted with battery management system prior to supplying any power to the fluid analytics system.

In other words, the battery management system checks whether any battery has enough energy and is a valid and qualified battery power source for the automatic power switching when it is just connected with battery management system prior to any automatic power switching for supplying fluid analytics system. If the output voltage of a battery recently inserted into battery management system is below the defined output voltage threshold of valid battery energy capacity, the battery management system will automatically isolate the battery by cutting off the connection to the battery using the over-discharge protection module.

The system may be configured to predict a battery empty state by monitoring the battery output voltage to determine whether the output voltage has descended below an output voltage threshold of the battery empty state. The output voltage threshold of the battery empty state may be a threshold indicative of energy capacity of the battery and may be between 5% and 10% of the maximum or full-charged battery energy In other words, when any battery's output voltage is equal or below the defined voltage threshold of battery empty state, it is in a battery empty state for battery management system.

The threshold level of the battery empty state is set to avoid the over-discharge of a battery.

The output voltage threshold of battery valid energy capacity or state may be a threshold indicative of the available energy capacity of the battery and may be between 50% and 80% of the maximum battery energy or between 70% and 80% of the maximum battery energy or between 80% and 90% of maximum battery energy or between 85% and 90% of maximum battery energy.

For any recently inserted battery of the plurality of batteries to the system, the system may be configured to predict a battery valid energy state by monitoring the output voltage of any one of the plurality of batteries by measuring the output voltage of any one of the plurality of batteries to determine the voltage being provided by any one of the plurality of batteries. To determine that the voltage provided by any one of the plurality of batteries is above the output voltage threshold of the battery valid energy state, the system generates a battery valid energy signal indicative of a sufficient level of energy capability of the respective one of the plurality of batteries and activates this battery valid energy signal until a battery empty state is detected. To determine that the voltage provided by the any one of the plurality of batteries is below the output voltage threshold of the battery valid energy state, the system generates a battery invalid energy signal indicative of a battery without enough energy and activates this battery's invalid energy state.

The respective battery valid energy signal or battery invalid energy signal may be fed to a logic control module which is configured to generate a battery valid signal, wherein the battery valid signal is fed to the over-discharge protection module. The over-discharge protection module switches off any battery with an empty state at any time, and also switches off any battery with a battery invalid energy state.

The logic control blocks in the battery voltage & current monitoring module only control the protection switches in the over-discharge protection module, rather than the power supply swap in the automatic channel swap module. The first logic control block in the battery voltage & current monitoring module may be configured to generate a first battery valid signal if the logic control block receives a battery valid energy signal for the first battery and, responsive to receiving the first battery valid signal, maintaining the related over-discharge protection switch on to connect the power supply channel of first battery with the automatic channel swap module and further wherein the second logic control block generates a second battery valid signal if the second logic control block receives a battery valid energy signal for the second battery and, responsive to receiving the second battery valid signal, maintaining the related over-discharge protection switch on to connect the power supply channel of the second battery with the automatic channel swap module.

The over-discharge protection module is to prevent battery over-discharge and increase the safety of the batteries and fluid analytics system by switching off the protection switches, 20 which connect the batteries to the automatic channel swap module.

The automatic channel swap module is independent from other modules within battery management system and swaps the power supply channels based on the priority of battery power supplies and their measured output voltages in this module. If the measured output voltages of the first one and second one of the plurality of batteries in the automatic channel swap module are above the battery cell cut-off voltage threshold corresponding to the 0% of the maximum or full-charged energy capacity, the automatic channel swap module will swap the power supply channels only based on the priorities of battery power supplies. In other words, the automatic channel swap module always chooses the power supply channel of the first battery with a high priority to supply power to the fluid analytics system when the measured output voltages of both of first and second battery are above the defined battery cell cut-off voltage threshold simultaneously. If the first or second battery is approaching the battery empty state, the over-discharge protection switch will switch off that battery in the over-discharge protection module, its power supply will be disabled by turning its over-discharge protection switch off first and its measured output voltage in the automatic channel swap module will be below the battery cell cut-off voltage threshold 5 immediately. The automatic channel swap module will automatically swap the power supply channel of the battery approaching an battery empty state to the power supply channel of another battery with a battery valid energy state. If both of first and second batteries are in the battery empty state, their over-discharge protection switches will be switched off firstly, their measured output voltages in the automatic channel swap module 10 will be below the battery cell cut-off voltage threshold, the automatic channel swap module will switch off their channel swap switches and the fluid analytics system is shut down.

Each logic control block may generate a battery valid signal using a logical AND gate which receives the respective a battery valid energy signal or battery invalid energy signal 15 as a first input and a main switch signal as a second input.

The logical AND gate may be a diode based logical AND gate.

The system may be further configured to detect the replacement of the first one of the plurality of batteries after the switch from the first one of the plurality of batteries to the second one of the plurality of batteries and to automatically switch the supply of electrical power from the second one of the plurality of batteries to the first one of the plurality of batteries.

The system may be further configured to detect the replacement of the second one of the plurality of batteries when the first one of the plurality of batteries is supplying the power and to automatically maintain the supply of electrical power from the first one of the plurality of batteries during the replacement of the second one of the plurality of batteries.

The system may be further configured to monitor the output current of at least one of the plurality of batteries in order to determine the discharge of excess current from the at least one of the plurality of batteries.

The system may be configured to be responsive to the determination of the discharge of excess current from at least one of the plurality of batteries, switch off the supply of electrical power from the at least one of the plurality of batteries and shut down the fluid 5 analytics system.

The one of the plurality of batteries may be the first one of the plurality of batteries and another one of the plurality of batteries may be the second one of the plurality of batteries.

Each of the plurality of batteries and its power supply channel has its own power supply priority level, different from the others of the plurality of batteries and their power supply channels.

The system may be further configured to determine the occurrence of a short circuit in the 15 system and, responsive to the determination of a short circuit, switch off the supply of electrical power from the at least one of the plurality of batteries and shut down the fluid analytics system.

The system may be further configured to determine that at least one of the batteries is 20 overcharged and, responsive to the determination that at least one of the batteries is overcharged, switch off the supply of electrical power from at least one of the plurality of batteries.

The system may be further configured to measure the battery fuel gauge and implement the 25 battery performance statistics analysis to predict the battery safety and performance trend through statistically analysing the output voltage, current, operating temperature of batteries.

Viewed from a further aspect, there is provided a battery management system for a fluid 30 analytics system arranged to receive an electrical power supply from a plurality of batteries. The system may comprise at least a first battery and a second battery. The first battery and the second battery may be included in the plurality of batteries, and each one of the plurality of batteries and its respective power supply channel has its own power supply priority level, different from the other batteries in the plurality of batteries.

The system in accordance with the further aspect may comprise a battery voltage and 5 current monitoring module which may be configured to predict a battery valid energy state and a batten/ empty state by monitoring battery output voltage from the at least first one and the second one of the plurality of batteries. The battery energy and current monitoring module may be configured to generate a discharge overcurrent signal by monitoring the output current of the at least first one or second one of the plurality of batteries and may be 10 configured to generate an overvoltage signal by monitoring the output voltage of the at least first one or second one of the plurality of batteries.

The system in accordance with the further aspect may also comprise a battery over-discharge protection module configured to respond to a battery valid energy signal to connect a respective battery to the automatic channel swap module by switching a respective over-discharge protection switch on, or respond to a battery empty state or battery invalid energy signal to disconnect a respective battery with the automatic channel swap module by switching a respective over-discharge protection switch off The system may further comprise an automatic channel swap module which independently chooses the power supply swap channel of the first one or the second one of the plurality of batteries to supply the power to the fluid analytics system based on the power supply priorities and the energy status of those two batteries.

The system may further comprise a battery fuel gauge and statistics analysis module to measure the fuel gauge and statistically analyse the output voltage, output current and operating temperature of the at least first one and second one of the plurality of batteries; The system may be configured to respond to the prediction of a battery empty state of the 30 first battery and to switch the supply of electrical power from the first one of the plurality of batteries to a second one of the plurality of batteries.

The system may be configured to respond to the prediction of a battery valid state of the second batten/ by switching the supply of electrical power from the first one of the plurality of batteries to a second one of the plurality of batteries.

The battery voltage & current monitoring module may comprise: a first voltage monitoring block which may be configured to monitor the output voltage of first battery and may be further configured to generate and activate a first battery valid energy signal to the first logic control block when the first battery is recently inserted (or being inserted) into the system and a battery valid energy state is detected, may be configured to generate and activate a first battery invalid energy signal to the first logic control block when the first battery is recently inserted into the system and in a battery invalid energy state, may be configured to generate and activate a first battery empty energy signal to the first logic control block when a battery empty state of the first battery is detected and may be configured to generates a first overvoltage signal to the fault detection block when the first battery is overcharged; and a first overcurrent monitoring block which may be configured to monitor the output current of first battery and may be configured to generate a first overcurrent signal to the fault detection block when an overcurrent is detected; and a first logic control block which may be configured to receive the first battery valid or invalid energy signal and the signal from the main switch, and generate a first battery valid signal to the battery over-discharge protection module by a logic AND operator; and a first power converter which may be configured to convert the power of the first battery to supply the first voltage monitoring block, first overcurrent block and first logic control block; and a second voltage monitoring block which may be configured to monitor the output voltage of the second battery, may be further configured to generate and activate a second battery valid energy signal to the second logic control block when the second battery is being inserted into the system and a battery valid energy state is detected, may be configured to generate and activate a second battery invalid energy signal to the second logic control block when the second battery is being inserted into the system and in a battery invalid energy state, may be configured to generate and activate a second battery invalid energy signal to the second logic control block when a battery empty state of the second battery is detected and may be configured to generates a second overvoltage signal to the fault detection block when the second battery is overcharged; and a second overcurrent monitoring block which may be configured to monitor the output current of second battery, and generates a second overcurrent signal to the fault detection block when an overcurrent is detected; and a second logic control block which may be configured to receive the second battery valid or invalid energy signal and the signal from the main switch and generates a second battery valid signal to the battery over-discharge protection module by a logic AND operator; and a second power convert which may be configured to convert the power of second battery to supply the second voltage monitoring block, second overcurrent block and second logic control block; and a fault detection block which may be configured to generate a system fault signal to the automatic channel swap module to cut off the power supply and shut down the fluid analytics system when receiving one of the first overvoltage signal, the first overcurrent signal, the second overvoltage signal and the second overcurrent signal.

The battery over-discharge protection module may comprise: a first battery over-discharge protection switch configured to disconnect the first battery with the automatic channel swap module in response to a battery invalid energy state or a battery empty state or connect the first battery with the automatic channel swap module in response to a battery valid energy state; and a second battery over-discharge protection switch configured to disconnect the second battery with the automatic channel swap module in response to a battery invalid energy state or a battery empty state or connect the second battery with the automatic channel swap module in response to a battery valid energy state; and a first driving circuit configured to turn the first battery over-discharge protection switch on to respond to a battery valid energy state of the first battery, or turns the first battery over-discharge protection switch off to response to a battery invalid energy state or a battery empty state of the first battery; and a second driving circuit configured to turn the second battery over-discharge protection switch on to respond to a battery valid energy state of the second battery, or drives the first battery over-discharge protection switch off to respond to a battery invalid energy state or a battery empty state of the second battery.

The automatic channel swap module may comprise: a first channel swap switch configured to choose the first battery and connect the first battery to fluid analytics system to supply the first battery's power to the fluid analytics system; and a second channel swap switch configured to choose the second battery and connect the second battery to the fluid analytics system to supply the second battery's power to the fluid analytics system; and a priority and load control block configured to monitor the input voltages of two channel swap switches and automatically turns on one channel swap switch and turns off another channel swap switch from the first and second channel swap channels simultaneously to only select one battery supply channel to supply power. This is based on the priorities of the channel swap switches and the comparison result between the measured input voltage levels and an output voltage threshold of the battery cell cut-off state.

The fuel gauge and statistical analysis module may comprise: a first voltage measurement block configured to measures the output voltage of the first battery; a first current measurement block configured to measures the output current of the first battery; a first temperature sensor configured to measure the temperature of the first battery; a first temperature measurement block configured to determine the temperature of the first battery through the first temperature sensor; a second voltage measurement block configured to determine the output voltage of second battery; a second current measurement block configured to measure the output current of the second battery; a second temperature sensor configured to measure the temperature of the second battery; a second temperature measurement block configured to determine the temperature of the second battery through the second temperature sensor; a first fuel gauge component configured to calculate the available capacity of the first battery based on the measured voltage, current and temperature of the first battery; a second fuel gauge component configured to calculate available capacity of the second battery based on the measured voltage, current and temperature of the second battery; a microcontroller configured to receive the data from the first and second fuel gauge component via a standard data bus, statistically analyse the performance and generate an alarm for the first battery or the second battery; a first communication component configured to transfer the data related to the first battery between the first fuel gauge component and the microcontroller; a second communication component configured to transfer the data related to the first battery between the second fuel gauge component and the microcontroller; a first bus isolator configured to physically isolate the communication bus between the first communication component and the microcontroller; a second bus isolator configured to physically isolate the communication bus between the second communication component and the microcontroller; a display unit configured to display the measurement results and statistics analysis results, wherein the display unit may be further configured to display an alarm output.

The system may be configured to predict a battery empty state by monitoring the output voltage of the first one or second one of the plurality of batteries to determine whether the output voltage has descended below an output voltage threshold of the battery empty state.

The output voltage threshold of the battery empty state may be an output voltage indicative of an energy capacity between 5% and 10% of the maximum battery energy at normal operating temperature.

The system may be configured to predict a battery valid energy state for a recently inserted battery by monitoring the output voltage of the first one or second one to determine whether the output voltage is above an output voltage threshold of the battery valid energy state. Wherein recently may mean within the previous minute.

The system may be configured to predict a battery invalid energy state for a recently inserted battery by monitoring the output voltage of the first one or second one to determine whether the output voltage is below the output voltage threshold of the battery valid energy state.

The output voltage threshold of the battery valid energy state may be an output voltage threshold indicative of the available energy capacity of the battery.

The output voltage threshold of the battery valid energy state may be a voltage indicative of an energy capacity between 50% and 80% of the maximum battery energy.

The output voltage threshold of the battery valid energy state may be a voltage indicative of an energy capacity between 70% and 80% of the maximum battery energy.

The output voltage threshold of the battery valid energy state may be a voltage indicative of an energy capacity between 80% and 90% of the maximum battery energy.

The output voltage threshold of the battery valid energy state may be a voltage indicative of an energy capacity between 85% and 90% of the maximum battery energy.

The method of overcoming the disturbance of the battery output voltage recovery that may be caused by the change of load connection is to check the output voltage of a just being inserted battery, determine whether the battery is in a battery valid energy state or battery invalid energy state and activate the detected energy state until the battery is approaching a battery empty state.

The output voltage threshold of the battery cell cut-off state may be an output voltage threshold indicative of 0% of maximum battery energy.

The method of extending the operating time of the fluid analytics system may comprise of automatic switching from the power supply of one battery with a high power supply priority and a battery empty energy state to the power supply of another battery with a lower power supply priority and a battery valid energy state among the power supplies of the plurality of batteries.

The method of extending the operating time of the fluid analytics system may be by automatic switching from the power supply of one battery with a low power supply priority and a battery valid energy state to the power supply of another battery with a high power supply priority and a battery valid energy state among the power supplies of the plurality of batteries.

DESCRIPTION

An embodiment in accordance with the aspect will now be described by way of example only and with reference to the following figures in which: Figure 1 schematically illustrates a gas analysis system including a battery management system in accordance with the embodiment; Figure 2 illustrates the battery output voltage fluctuation caused by the change of load connection when it approaches an empty state; Figure 3 schematically illustrates a battery management system in accordance with the 15 embodiment; Figure 3a is a state diagram illustrating the states which can be assigned to a battery by a system in accordance with the embodiment; Figure 4 is a flowchart illustrating how a battery over-discharge is overcome and how the electrical power supply from a battery to a fluid analytics system is switched between a first battery and a second battery using a battery management system in accordance with the embodiment; and Figure 5 illustrates the battery fuel gauge module which forms the basis of the statistical analysis of the batteries managed in accordance with the embodiment.

We describe an embodiment using an example of a gas analysis system but it will be understood that the embodiment could be used on any fluid analytics system.

We first illustrate, with reference to Figure 1, an arrangement which utilises the battery management system 104 of the embodiment. Figure 1 illustrates a fluid analytics system 100 which is configured to receive a supply of electrical power from one of a first battery 102a or a second battery 102b. First battery 102a and second battery 102b may be lithium-ion batteries but can be any suitable form of battery which can supply sufficient electrical power to fluid analytics system 100. The number of batteries is not limited to a specific number and is greater than or equal to two.

Fluid analytics system 100 may be a multipass or a singlepass fluid analytics system 100 configured to measure the absorption spectra from a sample gas which is fed into an absorption chamber and has light passed through it inside an absorption chamber. An example of such a system is described in W02017081662A1. The fluid analytics system 100 may be suitable for deployment in an ATEX regulated environment.

The direction of the supply of electrical power is illustrated by the bold solid lines. The electrical power from first battery 102a or second battery 102b is supplied to fluid analytics system 100 and is used to power the fluid analytics system 100 so that it can fulfil its 15 operational role in an environment such as an ATEX regulated environment where the fluid analytics system 100 is used to determine the presence of explosive compounds in the environment. Examples of such an explosive compound include benzene. The electrical power from the first battery 102a or the second battery 102b may also be supplied to the battery management system 104 to enable the components within to function accordingly. 20 Battery management system 104 monitors the output of first batten' 102a and second battery 102b and manages the switching between the batteries. The switching between the batteries is an important part of the operation of the fluid analytics system 100.

For the continued monitoring of the presence of gas emissions in the surrounding environment the switch between first battery 102a and second battery 102b must not provide any interruption to the operation of gas analysis system 100. That is to say, the battery management system 104 must enable an automatic "hot swap" between the first battery 102a and the second battery 102b This requirement to an automatic hot swap between batteries can prove problematic for battery management systems, especially for an automatic power supply swap within a power supply channel priority scheme. We illustrate the problem in Figure 2 which schematically illustrates how the output voltage from a battery behaves when the battery is nearly empty and is continually connected and disconnected with a load.

When a battery which is currently supplying the fluid analytics system 100 is approaching an empty state, its output voltage is more sensitive to the load variation. The battery empty state, which is when the battery goes toward between 5 and 10% of its maximum energy, easily leads to a fluctuation in output voltage readings which can confuse a battery management system such as battery management system 104.

As illustrated in Figure 2, when a battery supplying power to a fluid analytics system 100 (during the "Normal Supply" phase) hits the battery empty state, at, say, 5% of the maximum energy, the battery management system 104 typically switches from that battery, i.e. the first battery, to another battery, i.e. a second battery.

If the battery management system 104 is monitoring the output voltage of the batteries, the output voltage of the first battery will rise after it has been disconnected from the fluid analytics system 100. This might cause the battery management system 104 to determine that that first battery can supply power again, until the battery management system 104 determines, again, after a short period of time, that the first battery is almost empty and switches again to the second battery. This will repeat and generate continued inrush current pulses which will flood into the fluid analytic system 100 until the battery is exhausted and it is completely empty. This is illustrated by the "Automatic Switching Stage" in Figure 2. A completely empty battery and continued inrush current pulses are dangerous and will, in effect, confuse the battery management system 104 and a battery which is confusing the battery management system is dangerous. Allowing a battery to run until it is completely empty is also deleterious to the functioning of the battery. The output voltage fluctuations from the batteries supplying power to the fluid analytics system 100 is part of the nature of batteries, particularly lithium ion batteries, and the management of these output voltage fluctuations is crucial to the intrinsic safety of a gas analysis system which is working in an ATEX regulated environment.

We now describe a battery management system 300 which addresses this problem in Figure 3 where gas analysis system 308 is used as an example of fluid analytic system 100.

The battery management system 300 comprises a battery voltage & current monitoring module 302, an over-discharge protection module 304, an automatic channel swap module 306 and a battery fuel gauge module 310. This battery management system 300 is suitable for any hot swap and automatic switching battery application where continuous running is required.

The battery voltage & current monitoring module 302 is coupled to the first battery 102a and the second battery 102b which can supply electrical power to a gas analysis system 308 in accordance with the arrangement described with reference to Figure 1. The electrical power supply from the first battery 102a or the second battery 102b to the gas analysis system 308 is fed through the over-discharge protection module 304 and the automatic channel swap module 306 to the gas analysis system 308.

Current sensors la and lb monitor the output current from the first battery 102a to deliver a measurement of the output current from the first battery 102a. Current sensors 2a and 2b monitor the output current from the second battery 102b to deliver a measurement of the output current from the second battery 102b. It will be appreciated that two batteries are used as an example only. It will be understood that more than two batteries could be used and a combination of battery and mains power could also be used to provide electrical power to gas analysis system 308.

The measurements from current sensors lb and 2b are fed into a fuel gauge module 310.

The measurements from current sensors la and 2a are fed into battery voltage & current monitoring module 302 and particularly into respective first and second overcurrent monitoring blocks 312a and 312b.

First and second power converters 314a and 314b convert the output voltage from the respective first battery 102a and second battery 102b into a stable power supply, i.e. voltage VI and V2, for respective first voltage monitoring block 316a and second voltage monitoring block 316b, respective first overcurrent monitoring block 312a and second overcurrent monitoring block 312b, respective first logic control block 318a and second logical control block 318b as well as fault detection block 320.

The over-discharge protection module 304 comprises driving circuitry 324a and driving circuitry 324b which is arranged to move the over-discharge protection switches Sla and S2a between on and off positions. In the on position switch Sla will enable the supply of electrical power from the first battery 102a to the automatic channel swap module 306 and in the off position switch Sla will inhibit the supply of electrical power from the first battery 102a to the automatic channel swap module 306. In the on position switch S2a will enable the supply of electrical power from the second battery 102b to the automatic channel swap module 306 and in the off position switch S2a will inhibit the supply of electrical power from the second battery 102b to the automatic channel swap module 306.

The driving circuitry 324a or driving circuitry 324b moves the switches responsive to the detection of the respective battery valid signal for the respective valid battery energy signal or invalid battery energy signal as well as a main switch signal as will be described later.

The automatic channel swap module 306 comprises two channel swap switches (Slb and S2b) and a priority and load control block 326 which is arranged to monitor the input voltages and drive switches S lb and S2b between on and off positions. In the on position switch S lb will provide electrical power from first battery 102a to the gas analysis system 308 and in the off position switch S lb will cut off the supply of electrical power from the first battery 102a to the gas analysis system 308. In the on position switch S2b will provide electrical power from the second battery 102b to the gas analysis system 308 and in the off position switch S2b will cut off the supply of electrical power from the second battery 102b to the gas analysis system 308.

Indeed, only one of S lb or S2b can be moved into the on position at any one time and the supply of electrical power from either of switches S lb or S2b and a power supply from either supply channel can only take place if the respective over-discharge protection switch Sla or S2a is in the on position. The power supply channel priority between the first and second power supply channels means that the first power supply channel has a higher priority than the second power supply channel. That is to say, if the first power supply channel is determined to being supplying the correct level of power then it will always supply electrical power to the gas analysis system 308.

We now describe how the battery management system 300 automatically choose the supply of electrical power to the gas analysis system 308 from either of the first battery 102a or the second battery 102b when a battery empty state is predicted for the first battery 102a or when a first battery 102a which is determined to have insufficient capacity, i.e. it leads to the generation of a battery invalid energy state is inserted into the battery management system 300. The first battery is considered to be a priority supply of electrical power to the gas analysis system 308 and, as a priority supply of electrical power, the battery management system 300 will always supply electrical power from the first battery 102a provided it is providing sufficient electrical power and only switch to the second battery 102b when the battery empty state of the first battery 102a is predicted. When the first battery 102a with a battery invalid energy state is inserted, the battery management system 300 will continue to maintain the power supply from the second battery 102b with a battery valid energy state until the empty state of the second battery 102 is predicted.

To define a battery valid energy state or battery invalid energy state, corresponding to the proposed concept of battery valid energy capacity or state for a recently inserted battery, the output voltage threshold of valid battery energy state is adopted to check the energy state. This threshold voltage is equal or higher than the output voltage indicative to 50% of the maximum battery energy. That is to say, 50% of the maximum battery energy capacity is high enough for the battery management system 300 to avoid any difficulties associated with the level of output voltage fluctuations in Figure 2.

If the first battery 102a is recently inserted into the battery management system 300, the 30 first voltage monitoring block 316a monitors the output voltage from the first battery 102a by comparing the output voltage to the defined battery valid energy voltage threshold and determine the energy state of the first battery 102a prior to supply any power to the battery management system 300. If the output voltage from the first battery 102a is above the defined battery valid energy voltage threshold, the first voltage monitoring block 316a will generate and maintain a battery valid energy signal (BlEV) to activate and maintain a battery valid energy state for the first battery 102a. Otherwise, the first voltage monitoring block 316a will generate a battery invalid energy signal to activate and maintain a battery invalid energy state for recently inserted first battery 102a.

If the second battery 102b is recently inserted into the battery management system 300, the second voltage monitoring block 316b monitors the output voltage from the second battery 102b by comparing the output voltage to the defined battery valid energy voltage threshold and determine the energy state of the first battery 102a prior to supply any power to the battery management system 300. If the output voltage from the second battery 102b is above the defined battery valid energy voltage threshold, the second voltage monitoring block 316b will generate and maintain a battery valid energy signal (B2EV) to activate and maintain a battery valid energy state for the second battery 102b. Otherwise, the second voltage monitoring block 3 lob will generate and maintain a battery invalid energy signal to activate and maintain a battery invalid energy state for recently inserted first battery 102a.

A battery valid energy state of the first battery 102a or the second battery 102b will be changed into a battery empty state by the battery management system 300 when a battery empty state of the first battery 102a or the second battery 102b is predicted. The transaction from a battery valid energy state to a battery invalid energy state and then to a battery empty state is caused by the energy exhausted.

To predict a battery empty state, the first voltage monitoring block 316a and the second voltage monitoring block 316b monitor the output voltage from the first battery 102a and the output voltage from the second battery 102b respectively by comparing the respective output voltage to a defined battery empty threshold voltage (the output voltage threshold indicative of a battery empty state) which is indicative to approximately 5% -10% of the maximum battery energy capacity as shown in Figure 2. If the output voltage drops below the output voltage threshold then it indicates the battery is close to becoming empty which leads to the problems which are described in reference to Figure 2. The defined battery empty threshold voltage could be configured to be higher than 10% dependent on the application and could be between 10% and 50%.

That is to say, a battery which is already providing electrical power to the gas analysis system 308 can provide power until it is approaching the battery empty state.

In summary, battery voltage & current monitoring module 302 is configured to monitor the energy states of all of the batteries that could be used to supply power to the gas analysis system 308. The functionality of battery voltage & current monitoring module 302 is illustrated in Figure 3a using a state diagram from the perspective of a recently inserted battery.

As is evident from Figure 3a, the recently inserted battery can be assigned one of two 15 states initially, either a battery invalid energy state or a battery valid energy state. The recently inserted battery is assigned the battery invalid energy state if its output voltage is below the defined voltage threshold which is indicative of a battery valid energy state. The recently inserted battery is assigned the battery valid energy state if its output voltage is above the defined voltage threshold which is indicative of a battery valid energy state. 20 The battery invalid energy state is assigned permanently to the respective battery and it cannot be changed unless the battery is replaced with a new battery.

A battery which is assigned a battery valid energy state is then assigned a battery empty 25 state when its output voltage indicates the battery is at 5 to 10% of maximum energy. This threshold is configurable based on the application. More safety conscious applications may require a higher threshold to indicate a battery empty state.

The battery valid energy state of a battery can be transferred into the battery empty state 30 after it has supplied power to the gas analysis system 308 for a while. However, the battery invalid energy state is determined for a recently inserted battery and will be continually maintained for that battery. The power supply of that battery will be continually disabled until that battery was replaced by another new inserted battery with a battery valid energy state. The battery invalid state cannot be transferred into a battery valid state or battery empty state directly in any case.

The state of a battery is continuously monitored by the system 300.

Figure 4 shows how the battery management system 300 works when gas analysis system 308 is being powered on. Firstly, the main switch 328 of gas analysis system 308 is moved to the off position and a valid main switch signal is provided to both of logical control 10 block 318a and 318b to enable the power on of the gas analysis system 308 in step 400.

The first voltage monitoring block 316a monitors the output voltage from the first battery 102a and performs the comparison of the output voltage with the battery valid energy voltage threshold and battery empty voltage threshold in real-time and determines whether the first battery 102a is in a battery valid energy state, battery invalid energy sate or battery empty state in a step 5402. The second voltage monitoring block 316b also (in step 5402) monitors the output voltage from the second battery 102b and performs the comparison of the output voltage with the battery valid energy voltage threshold and battery empty threshold voltage in real-time and determines whether the second battery 102b is in a battery valid energy state, battery invalid energy state or battery empty state in step S402. The step 400 and step 402 are continually repeated to monitor and generate the energy state of either or both of the first and second batteries in real-time.

If the first voltage monitoring block 316a determines that the first battery 102a is in the battery valid energy state, the first voltage monitoring block 316a outputs a first battery valid energy signal (B1VE) to indicate to the logic control block 318a in a step 5404 that the first battery 102a can provide a sufficient level of electrical power to the gas analysis system 308. Otherwise, the first voltage monitoring block 316a outputs a battery invalid energy signal.

This B1 VE signal output is maintained until the first voltage monitoring block 316a determines that the output voltage by the first battery 102a has dropped below the battery empty voltage threshold, or the battery invalid energy signal of the first battery 102a is maintained until the current first battery 102a is removed and a new first battery 102a with a battery valid energy state is inserted into the battery management system 300.

Additionally, if the second voltage monitoring block 31613 determines that the second battery 102b is in a battery valid energy state, the second voltage monitoring block 316b outputs a battery valid energy signal (B2VE) to indicate to the logical block 3186 in a step 406 that the second battery 102b also can provide a sufficient level of electrical power to the gas analysis system 308. Otherwise, the second voltage monitoring block 316b outputs a battery invalid energy signal This B2VE signal is maintained until the second voltage monitoring block 316b determines that the output voltage by the second battery 102b has dropped below the voltage threshold of battery empty state, or the battery invalid energy signal of the second battery 102b is maintained until the current second battery 102b is removed and a new second battery 102b with a battery valid energy state is inserted into the battery management system 300.

If the battery valid energy signal B1VE is output as a true value in the step 404 and the valid energy signal B2VE is output as a true value in the step 406 at substantially the same time, either simultaneously or substantially at the same time, the logical block 318a outputs a battery valid signal Bl V to the driving circuit 324a of protection switch Sla in a step 408 and then the driving circuit 324a turns the protection switch S la to the on position to activate the supply of the power from the first battery 102a to the first channel swap switch Slb in a step 416.

At substantially the same time, the logical block 318b also outputs a battery valid signal B2V to the driving circuit 324b of protection switch S2a in the step 408 and then the driving circuit 324b turns the second battery's protection switch S2a on and activates the supply of the electrical power from the second battery to the second channel swap switch S2b in the step 416.

The step 416 indicates that both of first battery 102a and second battery 102b can supply a sufficient amount of energy and are ready to supply the power to the gas analysis system 308.

Further, the priority and load control block 326 switches the first channel swap switch S lb on to supply the power of first battery 102a to gas analysis system 308 in a step 426 while the priority and the load control block 326, at substantially the same time, maintains the second channel swap switch S2b in an off position to block the power supply of the second battery 102b to gas analysis system 308 in the step of 426 because of the priority of first channel swap switch Sib. The gas analysis system 308 is powered on and supplied in a step 432.

That is to say the power supply from the first battery 102a has priority over the power supply from the second battery 102b. The block on the supply from the second battery 102b to the gas analysis system 308 is only removed if the first battery 102a is approaching empty, i.e. if the output voltage from the first battery 102a drops below the battery empty threshold voltage.

If the battery valid energy signal BIVE is true in the step 404 and the battery valid energy signal B2VE is false in the step 406 at substantially the same time, the logical block 318a outputs a battery valid signal (B1 V) to the driving circuit 324a of protection switch Sla and the logical block 318b outputs a battery invalid signal to the driving circuit 324b of protection switch S2a in a step 410. Then the driving circuit 324a turns the protection switch Sla on to activate the supply of power from the first battery 102a to the first channel swap switch Slb, and the driving circuit 324b maintains the second battery's protection switch S2a in the off position and disconnects the power supply of the second battery to the second channel swap switch S2b in a step 418. Further, the priority and load control block 326 switches the first channel swap switch S1 b to the on position and, at substantially the same time, switches the second channel swap switch S2b to the off position to enable the supply of the power to gas analysis system 308 from the first battery 102a and to inhibit the supply of power from the second battery 102a in the step 426. The gas analysis system 308 is then powered on and supplied in a step 432.

If the battery valid energy signal B1VE is false in the step 404 and the battery valid energy signal B2VE is true in the step 406 at substantially the same time, the logical block 318a outputs a battery invalid signal to the driving circuit 324a of protection switch S la and the logical block 318b outputs a battery valid signal (B2V) to the driving circuit 324b of protection switch S2a in a step 412. Then the driving circuit 324a turns the protection switch Sla off and disconnect the power supply of the first battery 102a to the first channel swap switch Sib, and the driving circuit 324b turns the second battery's protection switch S2a on and activates the supply of power from the second battery to the second channel swap switch S2b in a step 420. Further, the priority and load control block 326 switches the first channel swap switch Slb to an off position and, at substantially the same time, switches the second channel swap switch S2b to the on position to enable the supply of electrical power to the gas analysis system 308 in a step 428. The fluid analytics system is then powered on and supplied in a step 432.

If the battery valid energy signal BlVE is false in the step 404 and, at substantially the same time, the battery valid energy signal B2VE is false in the step 406, the logical block 318a outputs a battery invalid signal to the driving circuit 324a of protection switch Sla and the logical block 318b outputs a battery invalid signal to the driving circuit 324b of protection switch S2a in a step 414. Then the driving circuit 324a turns the protection switch S1 a off and disconnects the power supply of the first battery 102a to the first channel swap switch Slb and the driving circuit 324b also turns the second battery's protection switch S2a off and disconnects the power supply of the second battery to the second channel swap switch S2b in a step 424. Further the first channel swap switch Slb and the second channel swap switch S2b are maintained in the off position because the input voltage on the first channel swap switch Slb or the second channel swap switch S2b is below the battery cell cut-off voltage in a step 430 by the priority and load control block 326 and gas analysis system 308 is switched off in a step 434.

That is to say, if the first battery 102a can provide sufficient power then the gas analysis system 308 receives its supply of electrical power from the first battery 102a. If the first battery 102a is determined to be incapable of supplying sufficient power then the supply is switched to the second battery 102b. If neither the first battery 102a nor the second battery 102b can provide sufficient power then the supply from both is cut off.

The logical control block 318a or 318b is a diode-based logical AND gate which is configured to output only a TRUE output signal if a battery valid energy signal (B1VE or B2VE) is received and the main switch 328 is switched to its off position to maintain the main switch signal as valid. The logical control block 318a or 318b simply consists of two diodes first diode and second diode (DI and D2) and a pull-up resistor.

For the logic control block 318a to operate, the signal from the main switch 328 is fed through a first diode Dl and the B1VE signal from the output of the voltage monitoring block 316a is fed through a second diode D2. The electrical power for the logic control block 318a is received from the power converter 314a when first battery 102a is connected to the gas analysis system 308. Only if the signal from the main switch 328 is a valid signal and the BINE signal from the first voltage monitoring block 316a is TRUE, the diode based logical AND gate provides a TRUE output, in the form of a B1 V signal.

For the logic control block 3186, the signal from the main switch 328 and the signal from the output of the voltage monitoring block 316b are fed through another first diode and another second diode. The electrical power for the logic control block 318b is received from the power convert 314b when the second battery 102b is connected to the gas analysis system 308. Only if the signal from the main switch 328 is a valid signal and the B2VE signal from the second voltage monitoring block 316b is TRUE, the diode based logical AND gate provides another TRUE output, in the form of a B2V signal.

The driving circuitry 324a or 324b drives the protection switch S I a or S2a. The switches S I a and S2a may be N-channel or P-channel MOSFET. The driving circuitry 324a or 324b is configured to respond to the first or second battery valid energy signal (BlVE or B2VE) from the logical control block 318a or 318b to change the state of switch S la or S2a.

The priority and load control block 326 provides an automatic power channel swap scheme that always automatically selects and switches to a power supply channel with a high supply priority and a valid input voltage to supply the power by switching its switch on and switch other switches off, based on the priorities of power supply channels and the detected voltages on the power supply channels in the automatic channel swap module. Here, the valid input voltage to the priority and load control block 326 means that it is higher than the batteries cell cut-off voltage which is indicative of an energy capacity of 0% of maximum battery energy, i.e. the battery is completely empty. If the detected voltage of a power supply channel with a high supply priority is below the battery cell cutoff voltage, the priority and load control block 326 will automatically select another power supply channel with a lower supply priority and valid voltage input in turn.

That is to say, the priority and load control block 326 is configured to determine that a battery is approaching empty and to automatically select another power supply channel to ensure a continued power supply is provided to the gas analysis system 308.

Switches S lb and 52b are back-to-back bidirectional P-channel or N-channel MOSFET which enable a complete isolation between the gas analysis system 308 and the respective battery.

Gas analysis system 308 is provided with a supply of electrical power from first battery 102a until a battery empty state is predicted by the battery management system 300 when the output voltage of first battery 102a drops below the battery empty voltage threshold to indicate it is approaching an empty state. Upon prediction of the battery empty state of first battery 102a, the voltage monitoring block 316a changes its output, currently the BIVE signal, into an invalid signal whilst the voltage monitor 316b maintains a battery valid energy signal B2EV for second battery 102b. Based on Figure 4, this means the current status of battery management system 300 is changed to the step 412, which automatically cause battery management system 300 into the step 420, step 428 and step 432. In the step 412, the logical control block 318a outputs a battery invalid signal to the driving circuit 324a of protection switch Sla and the logical control block 318b outputs a battery valid signal (B2V) to the driving circuit 324b of protection switch S2a. In the step 420, the driving circuit 324a turns the protection switch Sla off and disconnect the power supply of the first battery 102a to the first channel swap switch Slb and the driving circuit 324b maintains the second battery's protection switch S2a on and supply the power supply of the second battery to the second channel swap switch S2b. In the step 428, the priority and load control block 326 switches the power supply from the first battery 102a to the second battery 102b by switching the first channel swap switch S lb off and the second channel swap switch S2b to the on position at substantially the same time.

The first battery 102a can be then be removed and replaced at any time whilst the second battery 102b has a battery valid energy state, i.e. it is able to supply a sufficient level of electrical power. Similar to the case of detecting the empty state of the first battery 102a, upon detection by the battery management system 300 that the first battery 102a has been removed, the voltage monitoring block 316a changes its output, the B1VE signal, into an invalid signal whilst the voltage monitor 316b maintains a battery valid energy signal B2EV for second battery 102b. This also means the current status of battery management system 300 is changed to the step 412, which automatically cause battery management system 300 into the step 420, step 428 and step 432. In the step 428, the priority and load control block 326 automatically switches the power supply of gas analysis system 308 from the first battery 102a to the second battery 102b without interruption or the need for human vigilance.

Upon detection by the battery management system 300 that a first battery 102a with a battery valid energy state has been inserted in the battery management system 300 to replace the removed first battery 102a, the voltage monitoring block 316a changes its output from an invalid signal to a battery valid energy signal B1VE whilst the voltage monitor 316b maintains a battery valid energy signal B2VE for second battery 102b. This means that the current status of battery management system 300 is changed to the step 408, which automatically causes battery management system 300 into the step 416, step 426 and step 432. In the step 426, the power supply of gas analysis system 308 is switched from the second battery 102b to the first battery 102a by the priority and load control block 326.

That is to say, the battery management system 300 is configured to determine the energy state of a newly inserted battery and will only proceed to steps 416, 426 and 432 if the energy state is determined to be a battery valid energy state and that battery is connected to a power supply channel with a high-power supply priority. The effect of this being that the newly inserted battery will be rejected if it cannot provide sufficient power and power will not be drawn from the newly inserted battery.

The second battery 102a can be then be removed and replaced when the first battery 102a is supplying the power to the gas analysis system 308. Upon detection by the battery management system 300 that a second battery 102b has been removed, the voltage monitoring block 3I6a still maintain an activated battery valid energy signal BIVE for the first battery 102a and the voltage monitoring block 316b output an invalid signal for the second battery 102b. This means that the current status of battery management system 300 is changed to the step 410, which automatically causes battery management system 300 to transfer into the step 418, step 426 and step 432.

Upon detection by the battery management system 300 that a new second battery 102b with a battery valid energy state is inserted, the voltage monitoring block 316a still maintains a battery valid energy signal B1VE for the first battery 102a and the voltage monitoring block 316b outputs an new battery valid energy signal B2VE for the new inserted second battery 102b. This means that the current status of battery management system 300 is changed to the step 408 again, which automatically causes battery management system 300 to transfer into the step 416, step 426 and step 432.

Similar to the situation with the first newly inserted battery, the battery management system 300 will not proceed to steps 416, 426 and 432 unless a battery valid energy state of the first battery 102a is still determined.

For the scenario of power supply from more than two batteries, the battery management system 300 manages the power supply of multiple batteries to gas analysis system based on the same principle described in the above.

We now describe how battery management system 300 can be used to switch off the supply of electrical power to gas analysis system 308 in the event of an excess of current from either the first battery 102a or the second battery 102b during the operation of the gas analysis system 308.

As described earlier, first overcurrent monitoring block 312a and second overcurrent 5 monitoring block 312b receive measurements from respective current sensors la and 2a indicative of the output current of the first battery 102a and the second battery 102b during operation.

The discharge of current from the first battery 102a and the second battery 102b is measured and compared to a threshold current which is equal to the rated current of the cells in the respective battery. If the respective overcurrent monitoring block determines that the respective battery is discharging too much current, the respective overcurrent monitoring block transmits an overcurrent signal to the fault detection block 320.

Upon receiving the overcurrent signal, the fault detection block 320 generates a system fault signal. The system fault signal is transmitted to the priority and load control block 326 which, responsive to receiving the system fault signal, simultaneously moves the switches S lb and S2b into an off position to cut off the power to the gas analysis system 308.

The fault detection block 320 is configured to activate any identified battery overcurrent or overvoltage condition. When a battery overcurrent condition is detected by a respective overcurrent monitoring block, the respective overcurrent monitoring block generates a battery overcurrent signal to the fault detection block. When a battery overvoltage condition is detected by a respective voltage monitoring block for a battery, the respective voltage monitoring block generates a battery overvoltage signal to the fault detection block. Either a battery overcurrent signal or a battery overvoltage signal triggers a fault condition activated by the fault detection block 320 which will be described later to automatically shut down gas analysis system 308 and disconnect all battery connections to gas analysis system 308.

An excess of current from a battery can be dangerous as it can damage either the battery or the circuitry which is providing the electrical power to the gas analysis system 308 which might cause a fire risk. This means of cutting off the power supply from batteries and shutting down the system before an overcurrent or short circuit takes place reduces the risk of catastrophe in an explosive environment.

The first voltage monitoring block 316a or the second voltage monitoring block 316b are configured to generate a battery overvoltage fault signal which is transmitted to the fault detection block 320. The overvoltage fault signal is generated if the respective voltage monitoring block detects that an overcharged battery is being used to supply electrical power to the gas analysis system 308. Responsive to receiving a battery overvoltage fault signal, the fault detection block 320 output a system fault signal which is transmitted to the priority and load control block 326. The priority and load control block 326, responsive to receiving the system fault signal, is configured to move the switches S lb and S2b into an off position to prevent electrical power from being supplied to the gas analysis system 308.

We will now describe, with reference to Figure 5, the battery fuel gauge module 310 which is coupled to the first battery 102a and the second battery 102b. The fuel gauge module 310 comprises a first fuel gauge measurement component 330a and a second fuel gauge 20 measurement component 330b.

First fuel gauge measurement component 330a is configured to receive measurements indicative of the output voltage of the first battery 102a from the first voltage measurement component 332a, measurements indicative of the temperature of the first battery 102a from the first temperature measurement module 334a, and measurements indicative of the output current of the first battery 102a from the first current measurement module 336a. First temperature measurement module 334a receives temperature readings from the first temperature sensor 338a which is positioned adjacent to the first battery 102a to record its temperature. The first current measurement module 336a may receive current value readings from current sensors lb. Second fuel gauge measurement component 330b is configured to receive measurements indicative of the output voltage of the second battery 102b from the second voltage measurement component 332b, measurements indicative of the temperature of the second battery 102b from the second temperature measurement module 334b, and measurements indicative of the output current of the second battery 102b from second current measurement module 336b. Second temperature measurement module 334b receives temperature readings from the second temperature sensor 338b which is positioned adjacent to the second battery 102b to record its temperature. The second current measurement module 336b may receive current value readings from current sensors 2b.

The first fuel gauge measurement component 330a and the second fuel gauge measurement component 330b receive the measurements from the respective components and apply standard algorithms to the measurements to determine statistical trends in the respective data. This will enable the battery management system 300 to record any failures in the management of the batteries by a microcontroller 346 as if the first or second batteries experience surges in output current, voltage or temperature then this can be recorded by the fuel gauge measurement component 330a or 330b and fed to the microcontroller 346 through a respective first or second communication component 340a or 340b. The communication component then transits the information using a data bus isolated by a standard bus isolator 342a or 342b between the microcontroller 346 and the first or second communication component 340a or 340b.

The data buses from respective communication components 340a and 340b are then switched using a switching and translator component 344 and fed through the microcontroller 346 which generates an alarm accordingly after receiving the measurement results from fuel gauge measurement component 330a or 330b. The battery measurement results, battery performance analysis and alarm can be displayed on a display unit 348.

It should be noted that the above-mentioned embodiments illustrate rather than limit the 30 invention, and that those skilled in the art will be capable of designing many alternative embodiments without departing from the scope of the invention as defined by the appended claims. In the claims, any reference signs placed in parentheses shall not be construed as limiting the claims. The word "comprising" and "comprises", and the like, does not exclude the presence of elements or steps other than those listed in any claim or the specification as a whole. In the present specification, "comprises" means "includes or consists of and "comprising-means "including or consisting of'. The singular reference of an element does not exclude the plural reference of such elements and vice-versa. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

CLAIMS1. A battery management system for a fluid analytics system arranged to receive an electric power supply from one of a plurality of batteries, the system configured to: monitor energy output from each of the plurality of batteries to determine the energy state of each of the plurality of batteries; and further configured to, based on the determined energy state, select one of the plurality of batteries to provide a supply of electrical power to the fluid analytics system.
2. A system according to Claim 1, wherein each one of the plurality of batteries is assigned various power supply priority status and at least one of the plurality of batteries is assigned a high priority status and, responsive to the determination that the at least one battery has a valid energy state, the system is configured to select the at least one battery to supply electrical power to the fluid analytics system.
3 A system according to Claim 2, wherein the system is further configured to determine that the at least one battery with a high priority status has an empty energy state and, responsive to the determination, switch the supply of electrical power from the battery with a high priority status to a second battery until the system determines the first battery has a valid energy state.
4. A system according to any of Claims 2 or 3 wherein the system is configured to determine the at least one of a plurality of batteries is a recently inserted battery and further configured to determine the energy state of the recently inserted battery.
5. A system according to Claim 4 wherein the system is configured to reject the supply of power from a recently inserted batter if the system determines that the energy state of the recently inserted battery is a battery invalid energy state.
6. A system according to any preceding claim wherein the system is configured to determine that a battery energy state is a battery empty state and the system is further configured to cut off the supply of power from the respective battery.
7. A system according to Claim 1,2 3, 4,5, wherein the system is further configured to predict a battery valid energy state and generate and maintain a battery valid energy signal by monitoring the output voltage of a recently inserted battery to determine whether the output voltage is above a voltage output threshold indicative of enough battery energy capacity, or predict a battery invalid energy state and generate and maintain a battery invalid energy signal by monitoring the output voltage of a recently inserted battery to determine whether the output voltage is below this voltage output threshold.
8. A system according to Claim 7, wherein the voltage output threshold is indicative of an energy capacity between 50% and 80% of the maximum battery voltage.
9. A system according to Claim 7, wherein the voltage output threshold is indicative of an energy capacity between 70% and 80% of the maximum battery voltage.
10. A system according to Claim 7 wherein the voltage output threshold is indicative of an energy capacity between 80% and 90% of maximum battery voltage.
11. A system according to Claim 7 wherein the voltage output threshold is indicative of an energy capacity between 85% and 90% of maximum battery voltage.
12. A system according to any of Claims 5 to 11 wherein the system is configured to predict a battery empty state by monitoring the output voltage of each one of the plurality of batteries with valid energy states by: - measuring the output voltage of each one of the plurality of batteries to determine the voltage being provided by each one of the plurality of batteries with energy states; and - responsive to the determination that the voltage provided by the each one of the plurality of batteries is equal to or below the voltage output threshold of battery empty state, indicative of 5%--10% or more of maximum energy capacity, generating an invalid energy signal indicative of an energy state transaction from battery valid energy state to battery empty state.
13. A system according to Claim 7 and 12 wherein the respective valid energy signal or invalid energy signal is fed to a logic control unit which is configured to generate a battery valid signal, wherein the battery valid signal is fed to a battery over-discharge protection module which maintain a protection switch on to connect a battery to an automatic channel swap module to respond a battery valid signal, or cut off a protection switch to disconnect a battery to the automatic channel swap module to respond a battery invalid signal.
14. A system according to Claim 13 wherein the battery over-discharge module enables the first battery's power output to the first channel switch of the automatic channel swap module if the battery over-discharge protection module receives a first battery valid signal and, responsive to receiving the first battery's output voltage or both of the first battery and second battery's output voltage, the automatic channel swap module selects and maintains a supply of electrical power from the first one of the plurality of batteries and further wherein the battery over-discharge module enable the second battery's power output to the second channel switch of the automatic channel swap module if the battery over-discharge module receives the second battery valid signal and, responsive to only receiving the second battery output voltage, the automatic channel swap module switches the supply of electrical power from the first one of the plurality of batteries to the second one of the plurality of batteries.
15. A system according to any of Claims 11 or 12 wherein the logic control unit generates the battery output signal using a logical AND gate which receives the respective valid voltage signal or invalid voltage signal as a first input and a main switch signal as a second input.
16. A system according to Claim 15 wherein the logical AND gate is a diode based logical AND gate.
17. A system according to Claim 2, 3 and 13 wherein the automatic channel swap module independently selects the power supply channel of a battery with a high priority and a valid energy state to supply the power to the load, switches the power supply from the first one of the plurality of batteries to the second one of the plurality of batteries when the first battery is approaching a battery empty state and the second battery is at a valid energy state, or switch the power supply from the second battery to the first battery when a new first battery is recently inserted and at a valid energy state.
18. A system according to any preceding claim, wherein the system is further configured to detect the replacement of the first one of the plurality of batteries after the switch from the first one of the plurality of batteries to the second one of the plurality of batteries and to automatically switch the supply of electrical power from the second one of the plurality of batteries to the first one of the plurality of batteries.
19. A system according to any preceding claim, wherein the system is further configured to monitor the output current of at least one of the plurality of batteries in order to determine the discharge of excess current from the at least one of the plurality of batteries.
20. A system according to Claim 19, wherein the system is configured to, responsive to the determination of the discharge of excess current from the at least one of the plurality of batteries, switch off the supply of electrical power from the at least one of the plurality of batteries.
21. A system according to any Claim wherein the at least one of the plurality of batteries is the first one of the plurality of batteries.
22. A system according to Claim 20 wherein the system is further configured to determine the occurrence of a short circuit in the system and, responsive to the determination of a short circuit, switch off the supply of electrical power from the at least one of the plurality of batteries.
23. A system according to any preceding claim, wherein the system is further configured to determine that at least one of the batteries is overcharged and, responsive to the determination that at least one of the batteries is overcharged, switch off the supply of electrical power from the at least one of the plurality of batteries.
24. A fluid analysis system arranged to receive a supply of electrical power from one of a plurality of batteries, wherein the system comprises a battery unit configured to house the plurality of batteries and a system in accordance with any of Claims 1 to 23.
25. A fluid analysis system in accordance with Claim 23 wherein the fluid analysis system is a gas analysis system.
26. A fluid analysis system in accordance with Claim 23 or Claim 24 wherein the fluid analysis system is suitable for ATEX regulated environments.