Second point: The equivalent circuit of the battery is as follows, and the internal resistance of the battery exists.
The size of the internal resistance is related to the current (whether charging or discharging). When the current is large, the internal resistance is large. When the current is small, the internal resistance is small.
Why is charging voltage not used in calculating battery capacityie lithium?
When the OCV of a single lithium battery is lower than the 3.2V discharge platform, the self-discharge accelerates slightly. , and if it is not charged for a long time, it will cause excessive discharge.
Excessive discharge generally has two results. 1. The graphite layer collapses. 2. When the OCV is less than 2 V, copper ions start to migrate towards the positive electrode. copper dendrites appear and cause a short circuit. Eventually the battery failed completely.
The self-discharge of lithium batteries is relatively low when the power is 60%, generally less than 2%, so it is recommended to charge it every six months and adjust to SOC60%.
Lithium-ion battery is open circuit Analysis of the correspondence between battery voltage and capacity
First give a table: as follows, the percentage is the vsremaining capacity of the battery, and the right side is the open circuit voltage (OCV) of the corresponding battery.
100%----4.20V
90%- ----4.06V
80%-----3.98V
70%- ----3.92V
60% -----3.87V
50%- ----3.82V
40%--- --3.79V
30%-----3.77 V
20%--- --3.74 V
10%----- 3.68 V
p>5%------3.45V
0%---- --3.00V
Here are the ins and outs of this table
1. First some explanations of the concepts:
1.OCV: the abbreviation. open circuit voltage, open circuit voltage.
2. Lithium-ion Battery: This item This is the single-cell lithium-ion battery currently commonly used in mobile phones and is charged at a constant speed. voltage of 4.2 V.
3.mAh: The unit of measurement for battery capacity, which is actually the amount of energy in the battery that can be released for external use .
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The standard unit inphysics is the familiar Coulomb.
The international standard unit of Coulomb is current times time.Ampere-second.
1mAh=0.001 Ampere*3600 seconds=3.6 Ampere-second=3.6 Coulomb
The mAh is not a standard unit, but this unit can be easily used for measurement and calculation.
For example, a battery 900 mAh battery can provide 300 mA constant current power supply for 3 hours
.