Best Charge Current of Lithium Batteries

Charge current of Lithium Battery mentioned in our daily life refers to charge current in the fast charge phase. As a dynamic process, best charge current of lithium batteries is divided into three stages.

1. pre-charge best current: battery will undergo a pre-charge course when lithium battery initial/threshold value lowers pre-charge threshold value. For a single li-ion battery, this threshold values is 3.0V. In this stage, pre-charge current is about 10% current of next CC charge phase.

2. best CC charge current: the so called CC means constant current. Most CC charge current is set between 0.4-0.6C and 0.5C is mostly preferred. Full charge time is about 2 hours without considering other factors. The reason for choosing 0.5C is that this current is a good balance of charge time and charge safety.

3. CV charge current: in terms of single lithium-ion battery, when a certain voltage value arrives, battery enters CV charge phase, which features constant voltage and decreasing current. This current decrease is a gradual process. 0.01C cutoff current is chosen for most lithium batteries, which means end of charge process.

CC charge current design is the core of best charge current of lithium battery. It is be emphasized here that 0.5C charge current is suitable for most portable lithium batteries. For instance, for 18650 Lithium Battery with 1800-2600mAh conventional capacity, 1A charge current can be chosen; whereas for 1200-1500mAh lithium battery of high discharge rate type, 0.5C charge current is 0.7A.

Strictly speaking, largest charge current of lithium batteries is decided by battery structure, therefore each lithium battery producer has specified different charge current, yet highest charge current of portable lithium batteries should be 1C.

Of course, current design for pre charge and CC charge should also be considered. In these two phases, if initial voltage is not lower than 3.0V pre-charge threshold, pre-charge will not happen. In a word, pre-charge and CC charge phases before and after CC charge is advantageous to long-term use for lithium batteries.