GB2438656A

GB2438656A - Battery charging system for auxiliary batteries

Info

Publication number: GB2438656A
Application number: GB0610581A
Authority: GB
Inventors: Barry Chuter
Original assignee: Kigass Electronics Ltd
Current assignee: Kigass Electronics Ltd
Priority date: 2006-05-30
Filing date: 2006-05-30
Publication date: 2007-12-05
Also published as: GB0610581D0

Abstract

A system controls charging of a plurality of batteries (A1 to An) by a vehicle battery charging system (1), where the capacity of any one of the batteries is equal to or less than the capacity of the charging system but the total capacity of all the batteries exceeds the capacity of the charging system. The controlling system comprises switches (S1 to Sn) each connecting a number of the batteries to a charging line (L+) for connection to the charging system, where the total capacity of the batteries is equal to or less than the capacity of the charging system. A controller (2) is arranged to control the switches to charge each set of batteries from the charging system. Each set of batteries may be made up of one or more batteries. The system allows leisure vehicle and boat electrical systems greater capabilities without overloading vehicle charging systems.

Description

Battery Charging System

BACKGROUND OF THE INVENTION

Field of the invention

The present invention relates to a battery charging system. Embodiments of the invention described herein relate to an intelligent charging system for leisure/utility vehicles, for example caravans and camper vans, and boats amongst other examples.

Description of the Drior art

Electrical systems on leisure vehicles and boats are becoming more and more demanding, necessitating a larger auxiliary battery or set of batteries to power them. *: * Such vehicles have an engine which is integral with the vehicle as in a camper van or:...:.

an engine in a separate vehicle as used with a caravan. The vehicle engine typically has a charging system, having an alternator as the source of charge, and which is used to charge not only the vehicle battery but also the auxiliary battery or batteries. The *. * auxiliary battery or batteries can result, in some cases, in overload in the vehicle S...

charging system when the engine alternator is used. *:: : . As a result, vehicle and boat manufacturers are restricting the connection of auxiliary batteries to the charging system to a "safe" level, typically 120% the value of the engine battery. For example, an electrical system with a 1 OOAh starter battery would be restricted to a l2OAh maximum Auxiliary Battery. This, in turn, limits the capability of the electrical systems of the leisure vehicle and results in frequent flattening of the Auxiliary Battery when the system is used.

SUMMARY OF THE INVENTION

According to one aspect of the present invention there is provided a system for controlling charging of a plurality of batteries by a vehicle battery charging system, where the capacity of the any one of the batteries is equal to or less than the capacity of the charging system but the total capacity of all the batteries exceeds the capacity of the charging system, the controlling system comprising switches each connecting a predetermined number of the batteries to a charging line for connection to the said charging system, where the total capacity of the said predetermined number of batteries is equal to or less than the capacity of the charging system, and a controller arranged to control the switches to charge each set of a predetermined number of batteries from the charging system.

The predetermined number of batteries may be one. Alternatively the predetermined number of batteries is at least two.

The number of switches may equal the number of batteries.

The system may further comprise a sensor for producing a motion signal indicating whether or not the vehicle is prepared for, or is in, motion and a switch for isolating the batteries from a load which, in use, is energised by the batteries, the controller being responsive to the motion signal to cause the isolating switch to isolate the load from the battenes and charging system.

The present invention also provides a leisure vehicle comprising a system for controlling charging of a plurality of batteries according to the invention. The vehicle: : may comprise a domestic system as the said load. The domestic system may be one or more of lighting, entertainment systems for example television, a cooker and a refrigerator amongst other examples of domestic appliances andlor devices. The *:: : vehicle may be a caravan, a motor caravan, motor home, horse or race transporter or a boat amongst other examples.

Brief descript ion of the drawings For a better understanding of the present invention, reference will now be made by way of example to the accompanying drawings in which: Figure 1 is a schematic block diagram of an illustrative energy management system of a leisure vehicle including a battery charging system; and Figure 2 is an illustrative flow diagram describing a mode of operation of the energy management system.

The energy management system of Figure 1 is installed in a leisure vehicle, for example a caravan which is towed by a powered vehicle for example a car.

Alternatively the leisure vehicle itself may be powered by an engine as in a camper van or motor caravan. The powered vehicle has an engine including a vehicle S engine battery By and a battery charging system 1 including an alternator 14. The:..:.

vehicle engine battery, By, is connected to the charging system 1 and charged by S..

the alternator 14 in the conventional way. For convenience of description the following description assumes a combination of a caravan and a car. *.: *0a*

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The caravan has at least two auxiliary batteries and as shown in the example of::: Figure 1 has a set of a plurality of auxiliary batteries Al to An, where n is at least two. The set of auxiliary batteries Al to An has a capacity greater than the safe capacity of the charging system 1 of the car. For convenience of description the following description assume there is a set of a plurality of auxiliary batteries Al to An where n is greater than two, as shown in Figure 1. The auxiliary batteries are used to power electrical systems denoted as domestic systems 10 in Figure 1.

Those systems may be domestic lighting, cooking, entertainment (e.g. television) and food refrigeration systems of the caravan. The domestic system may include an inverter to convert the DC of the batteries to AC for powering the domestic appliances requiring AC.

The auxiliary batteries are connected in parallel to the domestic system 10. The positive terminals of the batteries Al to An are connected to a positive line L+ via respective switches Si to Sn. The engine battery By is connected to the line L+ via a switch Sv. The negative terminals of all the batteries are connected to ground.

An energy manager 2 which will be described in more detail below, controls the charging of the auxiliary batteries so that "split charging" (the charging of the engine battery By plus the auxiliary batteries Alto An) is achieved when the engine starts by closure of battery switch, Sv, and any combination of one or more auxiliary battery switches, Si to Sn. The combination of switches Sv and Si to Sn closed at any one time is chosen so the total capacity of the auxiliary batteries connected to the charging system i does not exceed its capacity.

The energy management system of Figure 1 also includes a switch Sout which controls the connection of the domestic system 10 to the charging system. The:...:.

switch Sout is controlled by the energy manager 2 in response to a signal produced by a source 12 denoted "motion sensor ". As described in more detail in GB-A-: :: 2395375 of Kigass Electronics Limited, the domestic system 10 of the caravan is isolated from the car when the car is in notion or prepared for motion as sensed by the sensor 12. The sensor 12 may be a sensor sensing disengagement of the hand bake of the car, or a signal derived from an automatic braking system or from a motion sensitive switch, or from the car's ignition switch.

The energy manager 2 controls the switches Sv and Si to Sn. (An optional Control Panel 8 is shown which could be used to help set up the system). The switches are controlled to enable charging of the batteries in such a way that the auxiliary batteries Al to An can be charged sequentially one at a time or in groups of two or more batteries i.e. not all at once, so the quoted "safe" level of the charging system 1 is not exceeded.

The control of charging may be time based (i.e. a fixed time for each battery in turn), or charge based (i.e. a measured charge in Ah)). This limits the total load on the vehicle charging system i to within manufacturers quoted safe level whilst charging a much higher overall battery capacity than would otherwise be permitted.

When the system is in normal use, i.e. not charging, but the domestic systems 10 are being used, the auxiliary batteries Al to AN may be switched in by the energy manager 2 (using switches Si to Sn) for use either individually or together, the result being that a much higher useable battery capacity is realised, without ever exceeding the designated safe charging level of the vehicle charging system 1.

As shown in the example of Figure 1, the alternator has a D+ line. This is an alternator charge signal line that is commonly present. It may used in this example to indicate to the energy manager 2 when to in conventional systems providing charge current so that the manger 2 can operate the switches Si to Sn. This could be used to control only switch Sv, if desired, with the Energy Manager 2 controlling the auxiliary battery *:. * switches, Si to Sn. : Other means of detecting charging (e.g. measurement of Battery Voltage), could * * :: equally well be used in the example of Figure 1. a a I...

The switches Sv, Si to Sn and Sout may be conventional relays. Other switches, for *::: : example solid state switches, may be used.

The system of Figure 1 also has a mains charger 4 and a solar charger 6. The energy manager 2 may control the at least the mains charger 4 switching it on as needed when the caravan and vehicle are connected to a mains supply to charge the batteries By and Al to An. The mains charger may have capacity to charge all the batteries or subsets of the batteries.

Referring to Figure 2, there is shown an example of a flow diagram describing a possible mode of operation of the energy manager 2 for controlling charging of the batteries.

A step S2, the manger 2 senses whether or not the vehicle is prepared for motion. That is done in response to the signal produced by the motion sensor 12. If the vehicle is prepared for motion, switch Sout is opened to isolate S4 the domestic systems 10 from the vehicle engine and it's charging system. Then at step S6, it is determined whether the alternator 14 is providing charge by for example sensing the D+ signal. If yes, the system conlinences split charging as will be described.

If the vehicle is not prepared for motion, at step S8 it is detennined whether the batteries need charging by for example sensing the voltages of the batteries. If yes, and the alternator is providing SlO charge, i.e. the engine is running, then split charging commences. If no then, at step S12, charging proceeds using the mains charger 4 andlor the solar charger 6.

Split charging comprises steps S14 to S22. Assuming the batteries are charged one at a time, at step S14 the first battery Al (n=1) is selected by closing switch Si.

The battery is charged according to a charging criterion e.g. for a fixed time charge, or *.: to a predetermined voltage. Once it is charged according to the charging criterion, n is:...:.

incremented S 18 by one and the next battery A2 and switch S2 are selected. Once all the batteries are charged, (step S20, n= nmax), the charging process stops S22. * : When batteries are charged, they have an additional "Bulk charge" phase * : where they will accept a greater current and therefore charge more effectively. The system may base battery switching on this., i.e., charging could be for the duration of the bulk charge phase before switching batteries.

In more detail, referring to Figure 1, assume each auxiliary battery is initially discharged. Each battery, in turn, is initially charged at high current in the bulk charge phase, for a fixed time or until a preset voltage is reached. Once all the batteries have been charged in that way, then each in turn is further charged to full capacity at a lower charging rate.

The batteries may be charged in groups instead of one at a time provided the capacity of each group does not exceed that of the charging system 1.

If batteries are to be charged in groups then there could be one group switch Sn per group, the number n of switches equalling the number of groups. Each such group switch would connect the positive terminal of all the batteries in the group to the line L+. * * * * * ** ** * S

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Claims

CLAIMS

1. A system for controlling charging of a plurality of batteries by a vehicle battery charging system, where the capacity of the any one of the batteries is equal to or less than the capacity of the charging system but the total capacity of all the batteries exceeds the capacity of the charging system, the controlling system comprising switches each connecting a predetermined number of the batteries to a charging line for connection to the said charging system, where the total capacity of the said predetermined number of batteries is equal to or less than the capacity of the charging system, and a controller arranged to control the switches to charge each set of a *: ** predetermined number of batteries from the charging system.

2. A system according to claim 1, wherein the predetermined number of batteries is one.

3. A system according to claim 1, wherein the predetermined number of:.* : batteries is at least two.

4. A system according to claim 1, 2 or 3, wherein the number of switches equals the number of batteries.

5. A system according to claim 1, 2, 3 or 4, further comprising a sensor for producing a motion signal indicating whether or not the vehicle is prepared for, or is in, motion and a switch for isolating the batteries from a load which, in use, is energised by the batteries, the controller being responsive to the motion signal to cause the isolating switch to isolate the load from the batteries and charging system.

6. A system for controlling charging of a plurality of batteries, substantially as hereinbefore described with reference to Figure 1 optionally together with Figure
2.

7. A leisure or utility vehicle comprising a system for controlling charging of a plurality of batteries according to any preceding claim.

8. A vehicle according to claim 7, which comprises a domestic system as the said load.

9. A vehicle according to claim 7 or 8, which is a caravan, a motor caravan, horse or race transporter, motor home or a boat. * * * * * *, ** * * * Is. * S S

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