How does the charger judge the charging condition of the lithium battery?

General chargers are constant current charging. Smart lithium-ion battery chargers usually take some time rather than immediately determining whether the battery has just been fully charged.

The lithium-ion battery can be judged directly according to the battery voltage. When the voltage exceeds the set cut-off voltage (generally 4.2V), it is considered that the battery is full; The advanced charger adopts the joint judgment of voltage and current. When the voltage approaches the cut-off voltage, it is switched to constant voltage charging. When the current is less than a certain set value, it is considered that the battery is fully charged.

This is determined by the way the charger judges. At present, the mainstream and recognized more accurate judgment methods are - △ V and 0 △ v. therefore, generally, the middle and high-end lithium-ion battery chargers mainly use these two judgment methods. However, after the battery is put into the charger and started charging, whether the battery is fully charged or not, the battery will not appear immediately or there will be a sufficient amount of - △ V or 0 △ v, However, it will take a period before there is - △ V or 0 △ V, which is enough for the charger to judge. Therefore, the intelligent charger takes a period and cannot immediately judge the battery that is fully charged.

On the contrary, the lithium-ion battery charger judged by the lowest voltage comparison method can judge the fully charged battery in a short time, because the voltage comparison charger only judges the battery voltage. As long as the battery voltage reaches, it will not judge whether the battery is full or not. Generally, the battery at that voltage is still far from saturation, that is, it is not fully charged. Therefore, this judgment method is generally only used on the lowest level lithium-ion battery charger.