Overcharge protection of walkie-talkie battery

How to understand Overcharge? 
The walkie-talkie continues to charge when the battery is full enough. 

What is Overcharge protection?

In the case of short-term (2-4h) overcharge, a protection method for lithium batteries to avoid battery damage such as swelling, leakage or even explosion due to overcharging (forgot to unplug the charging cable). 

Advantages of overcharge protection

Protect the battery, prevent damage, improve the service life and product quality.

 Realized method：

• With charging head and desk charger. 
  1. If the lithium battery has no overcharge protection, it is necessary to add a protection chip (similar to a power-off switch) inside the battery. When the battery voltage has reached the cut-off voltage (3.7V/7.4V), the power will be automatically cut off to prevent damage to the lithium battery. Continue charging.
  2. The matching charger (plug/base) is equipped with a circuit chip, it will judge that the current voltage of the battery is close to or reaches the cut-off voltage, automatically adjust the current, and continue to charge with a small current (100mA or even 10mA), and the battery voltage is short for a short time The internal voltage will not exceed the theoretical battery voltage (4.2V), so as to achieve the protection effect.
• USB charging.
  Use removable rechargeable batteries (No. 5, 7), this kind of machine comes with an overcharge protection chip (EN4045/LTC4045), which is controlled by the CPU.

• Retevis models have overcharge protection.
• All models of Retevis and Ailunce have overcharge protection function, but the protection method is different:
• <1> The back cover is a monolithic lithium battery (lithium polymer battery or two 18650 batteries) with a charging head and a base. Generally, it is realized with a charging head and a base, such as RT8, HD1, etc.;
• <2>Using USB charging models, generally use USB charging to achieve, such as RT36, RT49 and so on.