We now design electronic products, many times also use lithium battery power, the same as cell phones or tablets with lithium battery power, familiar with the knowledge of lithium battery capacity, perhaps the use and design of lithium battery power supply, including the design of battery chargers, it is necessary.
Now many people concerned about the discharge of lithium batteries, have the experience that when the lithium battery from the full voltage of 4.2V discharge to 3.7V, a long time, but once the 3.7V will discharge very quickly, yes, indeed.
Here are some information about some lithium batteries, to give you a summary.
First of all, the battery discharge platform, which refers to the fully charged lithium battery in the discharge, the battery voltage change state.
Battery constant current discharge, the battery voltage to go through three processes, namely, decline, stabilization, and then decline, in these three processes, the stabilization period is the longest. The longer the stabilization time, the higher the discharge platform of the battery. The high and low discharge platform is closely related to the battery manufacturing process. It is because the market positioning of each lithium battery manufacturer is different, the technical process means different, their control of the discharge platform is different, the quality is also very different.
In general, a 18650 lithium battery full voltage 4.2V, when discharged with a current of 1C to 3.7V, put 60 minutes, then we say the battery capacity is 2200mAh, in this time According to the characteristics of rechargeable batteries, make a graph as follows, you can better understand the battery capacity and voltage and current time and discharge platform relationship.
Capacity (C) = Discharge current × Battery discharge platform time
For a 18650 Li-ion battery with 2200mAh capacity, 1C discharging to 3.7V takes 1 hour.
Capacity(C)=2200mA×1hour=2200mAh
Then the question arises, for a good lithium battery, generally in our product testing will be in 3.7V after the voltage drop very quickly, then in a short period of time to put the power is very little.
On the contrary, the bad battery in 4.2V to 3.7V discharge, the voltage drops very quickly, and after 3.7V the voltage drops very slowly, this kind of battery is not good performance, and the general capacity is very low. Then the discharge platform of good lithium batteries is 3.7V.
In general, under constant voltage conditions, charged to a voltage of 4.2V, the current is less than 0.01C stop charging, and then set aside for 10 minutes, at any rate of discharge current, discharge to 3.7V, the length of time experienced by the battery discharge is an important indicator of the battery is good or bad.
However, do not just pursue a high platform, sometimes the platform voltage is high, but the capacity is reduced, because, under different multiplier conditions, the platform voltage is different, therefore, the platform should be considered from many sides. Both high capacity and long duration at the specified voltage is considered a really good battery.
