JP4705207B2 - Storage battery status monitoring method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for controlling a storage battery to a healthy state, and is used to measure the impedance and / or the charge voltage state of the battery of the storage battery.
Background of the invention Storage batteries are used to ensure the supply of energy in critical systems when breakdown occurs. Examples of such systems include traffic-related safety equipment, emergency equipment in hospitals and lighting backup systems, etc., and are used for energy generation and power distribution safety equipment, computers, and equipment used for telecommunications.
The state of the storage battery is ensured by regular maintenance. In the usual maintenance method executed twice to four times a year, the voltage and specific gravity of the cell in a state where the charger side is cut off are measured. The load test is performed once every 1-3 years. Also, storage battery connections and internal corrosion are typically measured by impedance and conductance measurements. When using Valve Regulated Lead Acid Batteries, there is the difficulty of non-uniform cell voltage. A further difficulty is the problem of cell drying which causes an increase in voltage, which is neutralized by sulfation which causes a decrease in voltage. Therefore, the voltage measurement does not necessarily tell whether the storage battery is in a healthy state. Measuring impedance and conductance is used as a normal maintenance method, but it is not 100% even if these measurements are compared with the state of the storage battery. In addition, large errors and strong temperature coefficients that occur even in cells in the same series make reading difficult.
In valve-regulated lead-acid batteries, what is also called thermal runaway caused by a negative coefficient between gas voltage and temperature, especially when using old and cheap chargers that lack a compensation temperature It becomes a big problem.
It is confirmed whether the storage battery is in a healthy state by a load test performed periodically. By comparing the increase in impedance, the test interval may be extended.
When measuring impedance and conductance using a normal 4-wire system (differentiating wires for current and voltage), it is necessary to remove the cover. It is difficult to successfully connect both current and voltage probes simultaneously. If the probe does not penetrate the lead oxide surface, the oxidized lead surface can be a source of inaccurate measurements.
U.S. Pat. No. 5,214,385 proposes a method for examining the state of a storage battery, where the state of charge of the storage battery is measured using a separate power source. In this case, the measurement affects the total battery voltage and the load voltage. In this investigation method , impedance is not measured . On the other hand, as will be apparent from the following description, the method used in the present invention does not require a separate power supply, so that the measurement does not affect the total voltage of the battery or the load voltage. Furthermore, according to the method of the present invention, it is possible to measure only the charging voltage together with the impedance.
When the cell is charged, electrical energy is used for chemical reactions and lead sulfate becomes lead oxide and lead. When the cell is fully charged, energy is used to break down the water. The gas generated near the electrode lowers the no-load current instead of increasing the cell voltage. The total battery voltage is adjusted to one level (usually 2.23 volts per cell for stationary lead-acid batteries) and even the worst cells are fully charged. In practice, this means a continuous overcharge that shortens the lifetime of the cell.
DISCLOSURE OF THE INVENTION Accordingly, one of the objects of the present invention is a method that can be used to pursue whether a storage battery is in a healthy state, in particular for measuring impedance and / or measuring the state of charge of a cell. It is to provide a method that can be used to measure internal corrosion based .
This object is achieved by the method detailed below. Another object of the present invention is to provide a method capable of maintaining the state of charge of a battery cell using a voltage somewhat lower than the normally used charging voltage. This prevents overcharging of the cell and extends the life of the cell. This object is also achieved by the method detailed below.
Embodiments of the present invention will now be described with reference to the accompanying drawings in which the present invention is shown in block diagram form.
Example In a no-load charge , a storage battery including cells 12 to 20 is connected to the charger 1. The cells 12 to 15 can be shunted by the current generator 6, and the cells 16 to 20 can be shunted by the current generator 8. In the no-load charging, if some has a cell is shunted, those cell voltage drops, whereas the other cell voltage increases. The total voltage of the storage battery does not change. By measuring the change in the cell voltage resulting from the shunt switch is turned on, the impedance of the cell is clear. Sampling and tracking voltage changes during many shunt periods reveals the cell voltage and state of charge .
Protection resistors 5 and 9 are calculated to withstand short circuits during maximum charging. The current shunt resistor 7 is not necessarily required if it does not worry about reducing the accuracy of the current generator. Instead of using the current generators 6 and 8, it is also possible to use a relay type control switch. The battery will also be divided into two or more shunt blocks. On the other hand, the present invention can be used as a single shunt block embodiment.
The basic principle of the present invention, a single or multiple cells, and shunted by a current generator 6, 8, is that attempts to read the state of charge in a change in cell voltage. Multiple samplings are performed during each shunt period . The sampling frequency during the shunt period is, for example, 3 Hz.
In the method according to the present invention, it is possible to measure the impedance by field operation or remote control and to elucidate the charging voltage state of a single cell or the entire cell block. The fixed current generators 6 and 8 can be used to apply a uniform voltage . The processor 10 performs signal processing, resolves the charging voltage condition by measurement, and switches the current generator on or switches to shunt cells that are not charged. In this method, the storage battery is kept in the correct charging voltage state. If it is detected that continuous charging is required, the processor issues a warning via the alarm output. When a cell with a low charging voltage is detected, either of the current generators 6 and 8 can be turned on for a certain period of time (for example, 10 minutes), and the charging voltage state is measured repeatedly, so that the cell is completely The cycle can be repeated until it is charged. In this method, continuous overcharge can be prevented.
The read signal is sent to the processor 10 via the multiplexer / AD converter 11. The method of the present invention can be connected to a remote monitoring device via a modem 3. Alternatively, the information is downloaded to the data collection device via a modem connector. Here, measurement results and information associated with the charging voltage Ru stored. When the network breaks down, the time, duration and measurements (such as voltage, current, temperature) are automatically stored.
The current generators 6 and 8, the multiplexer / AD converter 11, and the processor 10 are wired in the data acquisition device. As a result, no-load current, cell voltage, impedance, and charging voltage state are collected in the data collection device. In the simplest form, a data acquisition device would be used, with a pair of separate current generators and a probe.
Since all the cells are kept fully charged by the current generators 6, 8, the voltage of the charger 1 will be adjusted to a low level. Since there is no thermal runaway due to overcharging, it is possible to use an old charger for the valve-regulated lead acid battery.

Claims (3)

When the battery is a non-load state, using means that one or more battery cells Ru is shunted, the charge state and the impedance of each cell is measured, in the method for holding the battery in a healthy state ,
When the storage battery is in an unloaded condition, the one or more battery cells, through the current generator (6.8), or by shunting through switch and resistor (7), the remaining Place the battery cell without shunt,
During the shunt period , by continuously reading the individual cell voltages of battery cells that are not shunted , the voltage change in that cell is measured,
A method of maintaining the above-described storage battery in a healthy state, wherein one or more of the battery cells that are not shunted are controlled to obtain an equal voltage based on the voltage change . Two or more current generators, or at least two switches and resistors, are interposed between the storage battery poles and the connection points between the battery cells , and the current generators or switches connect the individual cells of the storage battery. 2. The method according to claim 1, wherein the shunting is alternatively possible. The measurement period of charge voltage status and equalization of each other's charge voltage until a cell detected as having a low charge voltage is fully charged or a warning is given that continuous charging is required. the method of claim 1 or claim 2, characterized in that repeated switching cycle period to achieve.

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