First give a table: as follows, the percentage is the remaining capacity of the battery, and the right side is the open circuit voltage (OCV) of the corresponding battery.
1. The abbreviation of OCVpen circuit voltage, open circuit voltage.
2. Lithium-ion battery: This article discusses a single-cell lithium-ion battery that is generally used on mobile phones with 4.2V constant voltage limit charging.
3. mAh: The unit of measurement of battery capacity, which is actually the total number of electrons in the battery that can be released for external use;
The unit equivalent to the physical standard is the familiar coulomb. The international standard unit of coulomb is the ampere second of current multiplied by time.
1mAh=0.001 Ampere*3600 second=3.6 Ampere second=3.6 Coulomb mAh is not a standard unit, but this unit can be conveniently used for measurement and calculation.
For example, a 900mAh battery can provide a 300mA constant current power supply capacity for 3 hours.
4. Fuel gauging electricity metering originally meant fuel metering, which was later cited as electricity metering in electrochemistry.
The most scientific and primitive battery fuel gauge method is to count the flow of electrons flowing through it.
Namely coulomb count (coulomb count).
In order to obtain the correct usage of the lithium-ion battery's power, only a coulomb meter is used. Just like the water meter used for water metering in your home. The power usage of the lithium-ion battery can be obtained by calculating the amount of charge flowing through. .
2. The relationship between voltage and capacity
However, lithium-ion batteries have a very useful feature for gas measurement, that is, when discharging, the battery voltage will gradually decrease with the elapse of power, and there is a considerable slope. This provides us with another approximate method of power measurement The method of taking the battery voltage. It is like measuring the water level in the water tank to roughly estimate the remaining water. But in fact, the battery voltage is more complicated than the calm water level measurement in the water tank.
Using voltage to estimate the remaining capacity of the battery has the following instabilities:
1. For the same battery, with the same remaining capacity, the voltage value changes due to the size of the discharge current.
The greater the discharge current, the lower the voltage. In the absence of current, the voltage is the highest.
2. The influence of ambient temperature on battery voltage, the lower the temperature, the lower the battery voltage of the same capacity.
3. The influence of cycling on the battery discharge platform. As the cycle progresses, the discharge platform of lithium-ion batteries tends to deteriorate. The discharge platform decreases. So the capacity represented by the same voltage has changed accordingly.
4. Li-ion batteries of different manufacturers and different capacities have slightly different discharge platforms.
5. Li-ion batteries with different types of electrode materials have different discharge platforms. The discharge platforms of drill lithium and manganese lithium are completely different.
All of the above will cause voltage fluctuations and voltage differences, making the battery capacity display unstable
When a mobile phone uses voltage to measure the battery capacity, because the mobile phone cannot always be in a low-current standby state. Temporary loss of large current, such as turning on the backlight, putting on the ringtone, and especially passing, will cause the battery voltage to drop quickly. When the mobile phone display capacity is reduced more than the actual capacity. When the high current is removed, the battery voltage will rise. This will cause the mobile phone capacity display to increase instead of this unreasonable phenomenon.