JPH02250275A - Method for judging life of lead-acid battery - Google Patents

Abstract

PURPOSE:To make high reliability judgement of the remaining lifetime of a lead acid battery by combining judgement on the basis of service duration with judgement on the basis of internal resistance value, and correcting the service duration with the ambient temp., the number of dischargings, and the lowest voltage at discharging. CONSTITUTION:The ambient temp. of a lead acid battery for a certain duration of time, the number of dischargings, and the lowest voltage at discharging for each run are sensed, and the service durations corrected with the ambient temp., the number of dischargings, and the lower voltage at discharging are accumulated for a certain specified period of time. Thus judgement is made in combination of the judging method, in which the exhaust of the life if determined from attainment of the preset service durations, with the judging method in which exhaustion is determined from the measured internal resistance of battery having exceeded the specified value. This enables judgement of remaining lifetime with reliability.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a method for determining the lifespan of a lead-acid battery, and more specifically, the lifespan is determined by counting the usage period of the battery and measuring the internal resistance. It is something.

Prior art and its problems Conventionally, in open lead-acid batteries, the end of life has been roughly determined by performing maintenance work such as ratio M measurement 1 and visual observation of the battery's appearance.

Furthermore, although sealed lead-acid batteries have the advantage of being maintenance-free, the methods conventionally used for open batteries cannot be used, and it is not possible to determine the end of their lifespan. For this reason, various devices have been devised to detect changes in charging/discharging voltage, changes in internal resistance, etc., and to determine the lifespan. Devices for determining the lifespan of storage batteries have not yet been put into practical use.

Therefore, to know the lifespan of a sealed lead-acid battery, the current method is to check the number of years it has been used and measure the floating charging voltage to make a rough judgment.

However, even this method does not take into account lifespan factors such as usage conditions, so reliability issues remain unresolved.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned problems by providing a method for determining life span that is simple in principle, reliable, and relatively easy.

Structure of the Invention The present invention detects the ambient temperature, the number of discharges, and the lowest voltage during discharge of a lead-acid battery for a certain period of time, and detects the ambient temperature, the number of discharges, and the discharge! 1. A method of determining the service life by calculating the usage period corrected by the low voltage for each fixed period, and determining the service life when the usage period reaches a preset usage period, and measuring the internal condensation of the battery, This is characterized in that a determination method is used in which the life is determined to be reached when the internal resistance value becomes higher than a specified value.

Example Hereinafter, one embodiment of the present invention will be explained in detail.

The method of determining lifespan based on the period of use is usually to count one count per day during the period of use of a lead-acid battery, and count up to the design life of the battery, but the design life is greatly influenced by the conditions of use. Therefore, use the daily count number corrected by the following formula.

In the margin below, in Equation (1), if the daily temperature change spans two or more ranges, only the temperature range for the longest time is applied. Charging usage 2.237/Q, ambient temperature 2
Table 1 shows a sealed lead-acid battery (at 5°C, no discharge) that was subjected to a floating charge life test while changing the ambient humidity. A discharge test was conducted at each temperature, and the lowest voltage during discharge was measured. The results are shown in Table 3.

Table 3 Two types of cycle life tests were also conducted at an ambient temperature of 25°C. The results are shown in Table 2.

Fu 2nd C in Table 2 indicates the 9 value of rated capacity.

From Tables 1, 2, and 5, it can be seen that the correction based on the ambient temperature and discharge conditions in equation (1) is appropriate. Therefore, it can be converted to the case where floating charge is used at 2.23 VA/I/, ambient humidity is 25° C., and there is no discharge, and the life can be determined by comparing with the design life.

Among the lifespan factors of lead-acid batteries, lifespan caused by drying up, anode plate corrosion, and internal short circuits cannot be determined by the above-mentioned method of determining lifespan based on usage period, but various lifespan test results have shown that it is possible to determine lifespan based on internal resistance. I know better. For example, when a sealed storage battery was subjected to a 0.025OA overcharge life test, and the internal resistance from the initial stage to the end of its life was measured using the AC four-terminal circuit shown in Figure 1, the result was as shown in Figure 2. That is, the internal resistance of the battery is initially 0.5 mΩ, but the capacity
1.4ffiQ when it drops to 80% of the rating (life)
) It was done. In addition, when the overcharge test was conducted on several of the batteries, the internal resistance was 0.48 to 0.52 at the initial stage.
The variation at the end of ntQS life was 1.37 to 1.42 #Ω, which was very small. Further, when the plurality of batteries were disassembled, all of them were found to be caused by corrosion of the anode plate.

FIG. 3 is a flowchart of a lifespan determination method using both the lifespan determination method based on the corrected usage period and the lifespan determination method based on internal resistance, and is applied to the sealed lead-acid battery.

In FIG. 5, first, the internal resistance of the battery under test is measured during floating charging, and if it is 1.37 mΩ or more.

At that point, the lifespan is determined to have come to an end. If it is less than 1.37 FF + Ω, the lifespan will be judged based on the period of use. That is, (1
) Check the counter that is counting using the formula method, and if it is 1825 counts) (365 x 5 counts) or more, which is the design life of 5 years, it is determined that the life is over.

If the battery is less than 1825 watts, it is determined that the battery is usable.
You can predict how long it will last.

Note 1: When the above implementation was tested in an open type lead-acid battery, results similar to those of a sealed lead-acid battery were obtained.Also, in this example, internal resistance was measured using the AC 4-terminal method. The method for measuring internal resistance is not limited.

Effects of the Invention As detailed in the embodiments, the present invention provides a sealed lead-acid battery 1.
It is possible to determine the lifespan of an open lead-acid battery based on the usage period and the internal resistance value, and by using both together, the usage period can be corrected based on the lead-acid battery's ambient temperature, number of discharges, and minimum voltage during discharge. This allows highly reliable life judgment.

[Brief explanation of drawings]

Figure 1 is a wiring diagram of an AC four-terminal circuit for measuring the internal resistance of a sealed lead-acid battery, which is an embodiment of the present invention, and Figure 2 is the relationship between internal resistance and capacity of a sealed lead-acid battery in an overcharged state. FIG. 3 is a flowchart showing the procedure of an embodiment of the present invention. 1... Battery under test 2... Constant current source 3...
voltmeter

Claims (1)

[Claims] A lifespan determination method that measures the ambient temperature, number of discharges, and minimum voltage during discharge of a lead-acid battery over a certain period of time, and uses the usage period corrected based on the ambient temperature, number of discharges, and minimum voltage. A method for determining the lifespan of a lead-acid battery, characterized in that: and a method for determining the lifespan in which the internal resistance of the battery is measured and the lifespan is defined as the time when the internal resistance value becomes higher than a specified value.