# How to test the rechargeable battery pack test?

## Method for detecting capacity of rechargeable battery

For example, a 1500mAh rechargeable battery is fully charged. The discharge current of 1500mA can reach 1 hour to prove that the capacity is sufficient. If a 750mA rechargeable battery is used, discharge it for 2 hours for capacity testing. But when the voltage is 0.9Volt (1.2Volt rechargeable battery), there is still a nominal current discharge, how to understand.

Battery capacity refers to the use capacity of the battery. Therefore, when the 1500mAh rechargeable battery is discharged from 1.45Volt to 0.9Volt, the capacity we need is the capacity we need. We don’t use the capacity below 0.9Volt, and the discharged power is not much (too low discharge will also Affect the service life of the battery), usually the discharge platform of a high-quality rechargeable battery is more reliable, for example: a 1500mAh battery is discharged from 1.45Volt to 0.9Volt at a current of 0.5C, and it is left for 120 minutes, then we will say that the battery is The actual use capacity is 1500mAh. The relationship between current, voltage and time in 120 minutes is shown in the figure:

On the contrary, when the discharge voltage of the inferior battery is from 1.45Volt to 0.9Volt, the battery voltage drops quickly, and the voltage drops relatively slowly after 0.9Volt, indicating that the battery performance is not good enough, and the capacity is usually very low.
Note: I: the basic unit of current, ampere or milliampere;
F: The unit of the capacity of the reaction capacitor to store charge, [1/hour], when narrating, only \”number\” is often mentioned, not the unit;
C: Battery charge and discharge capacity ratio, namely battery capacity, unit: ampere hour or milliampere hour
For example, when the battery capacity is 1000mAh, it is charged at a current of 0.1C, which is equivalent to clear:
The charging current to the battery I=0.1[1/hour] X1000[mA hour]=100[mA]
F is also called \”charging (discharging) rate in n hours\”, f =1/(n hours)

When the battery is charging, the battery voltage is detected by the charger. When the detected voltage reaches the specified voltage value, it is considered to be fully charged. The accuracy of plus or minus 1% is the accuracy of the voltmeter that measures the voltage. If you want to monitor the charge and discharge of the battery, you can look for references in related circuit books. Through the capacitance calculation formula, calculate the resistance of the load and discharge through the standard discharge current, and detect the voltage. If the voltage reaches or is not much different from the standard discharge time, it is fine.

In addition to the above methods, you can also use tools to test, for example, use a multimeter to test rechargeable batteries:

①: Disconnect the battery and measure the battery voltage. If the battery voltage is significantly lower than the nominal voltage, please put the rechargeable battery into the battery charger first, and then let the device charge for a period of time.

②: Turn on the multimeter and adjust the measuring knob to detect the DC current. Make sure that the dial is set to at least measure the maximum voltage that the battery can provide. If the setting on the multimeter matches the voltage provided by the battery, set the dial to measure the next higher voltage value. For example, after a 12V battery is fully charged, its no-load voltage can reach about 13.7V

③: Touch the metal tip of the black probe lead of the meter to the negative (-) end or terminal of the battery, and then touch the metal tip of the red probe lead of the meter to the positive (+) end or terminal of the battery. When touching them to the battery, observe the voltage reading on the display of the multimeter. If the voltage is significantly lower than the voltage that the battery should have after a full charge, the battery may be near the end of its useful number of charges