How To Charge Li-Ion Rechargeable Batteries
Li-ion batteries are the most popular batteries when it comes to home appliances. That is due to the fact, that they have higher nominal voltage and can be designed in small sizes. Therefore, they have higher energy density and higher capacities. In addition, lithium-ion batteries can be charged at any time, because they do not suffer from memory effect. Even if you leave them uncharged for a long time, these rechargeable batteries do not damage like Ni-Mh and Ni-Cd batteries.
Charging Li-Ion 3.6V Rechargeable Batteries
Lithium-ion batteries with cathodes made of cobalt, nickel, manganese and aluminum materials are charged up to 4.2V per cell. It is possible to observe tolerance to +/- 50mV per cell. Some versions of these rechargeable batteries have nickel terminals that can be charged up to 4.1V per cell. Other Li-ion batteries with high capacities can be charged up to 4.3V per element. Higher voltage results in increased capacity, but when it goes beyond the battery specification, the cell degrades and shortens its life.
The rate at which li-ion rechargeable batteries are required to charge is between 0.5-1C and the full charging time takes about 2-3 hours. Most Li-ion battery manufacturers recommend charging at 0.8 ° C or less to prolong their life.
Unlike sealed-lead acid batteries, it is not necessary or required to top charge Lithium-Ion. In addition, it is not recommended to fully charge these batteries, because the high voltage “stresses” the battery and shortens its life. Fully charging Li-ion batteries may shorten their life, but on the other hand it increases the usage time of the battery. In order to satisfy consumer’s needs for longer charging times, most of the chargers are designed at maximizing the charging capacity to increase in service life.
Charging Other Otpes Of Li-ion Rechargeable Batteries
Standard lithium-ion rechargeable batteries use cobalt, nickel, manganese or aluminum as an active material for the cathode, thus they achieve a nominal voltage of 3.6V or 3.7V. Other types of Li-ion cells use different materials which means nominal voltage is different. For example, Lithium Iron Phosphate technology batteries have a nominal cell voltage of 3.2V and they are can charge up to 3.65V. Another kind of Li-ion battery is the one that uses LTO technology. Its nominal voltage is 2.40V and can be charged up to 2.85V.
Chargers designed for alternative types of Li-ion rechargeable batteries are not suitable for the standard 3.6V and 3.7V lithium-ion batteries. For example, should you try to charge a typical 3.6-volt battery with an alternative charger, it will not be able to charge it properly. Otherwise, when charging an alternative Li-ion battery with a charger designed for standard lithium-ion batteries, it will shorten the battery life.
Recharging of Li-ion Batteries
Li-ion rechargeable batteries are designed to work within certain operating voltages. This type of batteries becomes unstable and unsafe for use if the battery is charged at a higher voltage than required. Increasing the voltage to 4.30V forms lithium deposits on the anode, cathode oxidizes and thus, the battery loses stability and begins to produce carbon dioxide (CO2). Hence, the internal resistance increases.