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# How to measure battery charge

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The capacity of the battery is the time that the battery can supply the connected load.

Standard capacity is measured in ampere-hours, and for small batteries - in mielamper-hours.

Instructions

1

The amount of electricity (charge) in the battery is usually called the capacity. The charge is measured in Coulombs, 1 Pendant is 1 Ampere x 1 second. In order to know the capacity Accumulator, Charge it completely, and then discharge by the set current I and measure the time T, during which the total discharge will occur. Multiply the time (T) by the current (I), and you get a Q-capacitance Accumulator.

2

To test, fully charge the battery andConnect it to this device. Set the clock on the & lt-0 & gt- and enable Start. Now the relay should close the contacts 4-5, and also 5-6, and the battery starts to discharge through the resistor R, the clock is energized. The voltage on the battery itself and on the resistor starts to decrease slowly, when it drops to 1V on the resistor, the relay opens the contacts, the discharge stops, and the clock stops.

3

With discharge Accumulator Control current passing through contacts 1-2Relay, falls from 8 to 2 mA. If the control current is 3 mA, then the resistance of the contacts 4-5 and 5-6 is less than 0.04 Ohms (the value is low enough to not take it into account when measuring current). If you need a discharge current of 1A, then use a resistor R = 1.2 ohms.

4

After the discharge stops, the voltage on the battery starts to rise to 1.1-1.2 V, this is due to the internal resistance of the cell. Take into account the fact that the capacity of a newly charged Accumulator Will be higher, because after some timePart of the charge is lost self-discharge. In order to calculate the amount of self-discharge, measure the capacitance immediately after charging, and then about a week after that. Some batteries have a self-discharge rate of 10% per week or more.

5

If you work under this scheme, try to decrease the resistance of the contacts Accumulator And connectors. If the current is 0.5-1 A, you can get a not very high measurement accuracy (lose at contacts from 0.1 V and more). Also, the steel spring can cause losses precisely, which is used in some holders Accumulator, So her and other contacts from steel shun with a copper wire.

How to measure battery charge Was last modified: May 21st, 2017 By
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