How does a lithium-ion battery recharge?
People will think of charging a battery as easy as to fill up a bracket with water, just open the tap until it is full. From the outside, that’s exactly how it works, but inside the battery, it is more complicated.
A lithium-ion battery typically charges in two stages the first process is called constant current charging. This is a very simple stage. To charge up your mobile phone or tablet will apply a steady current of electricity to the battery to get all those electrons back to the anode. The charger just decides how much power is coming out during this stage. The higher that constant current, the faster the battery can charge. But when the battery is recharged up to 70 percent, the procedure changes and flips over to constant voltage charging.
During this second stage, the charger makes sure that the voltage is difference in current between the batter and the charger, will stay the same rather than keeping the current constant. This means the battery is very closed to full charge, the current the charger send into it decreases. The rate at which it charges slow down when the battery is full. Once the battery is 100 percent charge up, the charge will trickles in, just enough to account for the tiny bit of charge you battery loses naturally over time.
You do not need to worry about the lithium battery overcharge. As in Li-ion rechargeable device nowadays, they will have power management IC, this IC is to design to prevent overcharging the battery.