Charging Lithium-ion Battery

Posted on December 26, 2018

Lithium-ion (or Li-ion) batteries are one of the most common types of rechargeable batteries with multiple applications for a wide range of devices. Compared to nickel-cadmium batteries, lithium-ion batteries offer several advantages, which is why they’re growing in popularity.

Advantages of Lithium-ion Battery

The density of energy of Li-ion batteries is almost twice that of nickel-cadmium batteries with the potential for more energy density.

The discharge is quite satisfactory too.

The high voltage of 3.6 volts allows battery packs to run with only one Li-ion battery as compared to nickel-cadmium battery packs that require three 1.2 volts batteries to be connected in series to deliver the same voltage.

Li-ion batteries require minimal maintenance and cause little harm to the environment when disposed of.

Charging Your Li-ion Batteries

Standard Li-ion batteries with cathode comprising nickel, cobalt, aluminium and manganese typically charge up to 4.20 volts per cell with a tolerance level of +/- 50 millivolts per cell. Some high capacity models may even charge up to 4.30 volts per cell or even higher.

Enhancing the voltage increases the capacity of the batteries but going beyond the specified limit can overstress the battery and affect its longevity. Therefore, many models have inbuilt protection circuits that do not allow you to charge beyond the specified limit.

It is advisable that the charge rate of your Li-ion battery be kept between 0.5C and 1C with complete charging time between 2hrs and 3hrs. The optimum rate should be kept at about 0.8C.

Your Li-ion battery is fully charged when the voltage reaches the recommended threshold and the current falls to 3% of the rated input.

Prolonging the Life of your Li-ion Batteries

Lithium-ion batteries should never be fully charged. In fact, manufacturers strongly advise against fully charging your batteries as the high voltage stresses it out quickly.

Choosing a lower voltage threshold or avoiding charging it to the saturation point prolongs the life of your battery, although the runtime is reduced. However, those using Li-ion battery for consumer products prefer full charge as the runtime is more important than the service life.

Some chargers use a fast method of charging that quickly charges your batteries to about 85% (which is sufficient enough) within an hour or sooner thereby avoiding the saturation point and increasing the life of your batteries.

Certain industrial chargers set the threshold at a lower level on purpose so as to prolong the life of your Li-ion batteries.