What is detection principle of remaining battery power?

1500mAh rechargeable battery with fully charged. A discharge current of 1500 mA can reach 1 hour, indicating that capacity is sufficient and if using some 750mA discharge for 2 hours to detect it there is still a nominal current release when voltage is 0.9V (1.2V rechargeable battery), why?

The battery capacity we refer to actually refers to the battery capacity. That is to say, the discharge of 1500mAh rechargeable battery from 1.45V to 0.9V is the capacity we need. The capacity released below 0.9V is not used, and the amount of electricity discharged is not much (discharge is too low). Will also affect the battery life), generally, good rechargeable battery discharge platform is better, such as 1500mAh battery from 1.45V to 0.5

The current discharge of C put to 0.9V and put for 120 minutes. Then we say that the battery capacity is 1500mAh. The relationship between current and voltage during this time is as follows:

Detection method of Rechargeable battery capacity

The discharge platform of a good battery will drop rapidly after 0.9V, so the amount of electricity discharged in a short time is very small. On the contrary, when the battery discharged from 1.45V to 0.9V, the voltage drops rapidly, and after 0.9V, the voltage drops slowly. The battery has poor performance and the general capacity is very low.

Note: I: ampere or milliamp;

f: [1/hour], the narrative often only says \"number\", not the unit;

C: Battery capacity, unit: ampere or mAh.

For example, when the battery capacity is 800mAh, it charged at a current of 0.1C, which is equivalent to clear:

Charging current for battery I=0.1[1/hour]X800[mAh]=80[mA]

f is also called \"n hour charge (discharge) rate \", f = 1 / (n hours)

When we measuring battery capacity usually is measuring battery voltage. Charger detects battery voltage while charging, and considers it to full when voltage reaches specified voltage value. If voltage of lithium-ion battery charged to 4.2V, it considered full. Accuracy of voltmeter for detecting voltage is to achieve an accuracy of plus or minus 1%. Lithium-ion battery damaged due to overcharging. If you want to monitor the battery charge and discharge, there are very mature circuits in book for reference. If you just want to measure it, then it is easy to handle. Calculate load resistance according to capacity and discharge it with standard discharge current. Then check the voltage, as long as it is enough to reach or approach nominal discharge time.

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