How to measure lithium battery capacity with a multimeter
Strictly speaking, a multimeter can only measure current, voltage, and resistance, but not capacity. But you can use a multimeter to roughly measure whether the capacity of the lithium battery is insufficient, that is, use the DC current range of the multimeter (preferably a pointer meter). Instantly measure the positive and negative polarity of the battery. If the current displayed on the meter is very large, it means that the battery has capacity. If the displayed current is very small, the battery capacity is insufficient, but this method is a destructive measurement method. In fact, it is equivalent to short-circuiting the battery to take a look. Therefore, it should be contacted at any time when measuring. Absolutely not for a long time. Otherwise even a good battery. Also turned off the electricity.
Originally, a multimeter is not suitable for measuring the capacity of lithium batteries, but it is not impossible to measure, it is just unprofessional. The following is an introduction to the method of measuring the capacity of lithium battery with a multimeter.
Equipment: multimeter, small light bulb or high-power resistor, timer or mobile phone.
After the battery is fully charged, leave it empty for 2 hours, measure the no-load voltage, and record it. Connect a small light bulb or a resistor and measure the current. The current is best controlled at about 1/10 of the capacity. Measure the current every 1 hour. You can also measure the voltage and convert it into current. When it reaches 3.2V, every 10 minutes Measure current and voltage. Stop measuring until the voltage drops to the protection voltage to prevent damage to the battery due to over-discharge.
Add up all the current times to get the capacity of the lithium battery.
This is a more accurate measurement. For a rough measurement, the current can be regarded as constant, and the discharge time of the intermediate value of the current can be used directly.
The capacity of the battery cannot be measured with a multimeter
However, some friends will use a multimeter to test the short-circuit current of the battery to roughly judge the capacity of the battery. Using this method to pair a battery pack of the same specification, the effect is not bad, but some batteries have normal open-circuit voltage. Once the short-circuit current is measured, it will be revealed. .
Measuring the short-circuit current (if the current value is within the range allowed by the multimeter and the battery), can only compare the power of the same type of battery. Different models cannot be compared, because the standard internal resistance of different types of batteries is different, even if the power of the memory is the same, the short-circuit current is also different.
