The standard method for charging Lithium-ion (Li-ion) batteries is the constant current/constant voltage (CC/CV) method. It incorporates a two-step process of constant current (CC) followed by a constant voltage (CV) charge phase. In the first stage of the charging process, a constant current equal to or lower than the maximum charge rate for a particular cell is applied. This stage continues until the battery pack voltage approaches the preset threshold at the charger contacts. Once the charging voltage approaches the preset level, current begins to taper exponentially until a cutoff threshold is achieved.
Although CC/CV is widely used across the battery industry, it does have limitations. The charging voltage is fixed and typical chargers cannot compensate for changes of a resistive string within the battery pack. If faster charging is needed, for example, the constant charging current would need to be increased, inducing even greater internal losses.
Realizing the limitations of standard CC/CV chargers, ICCNexergy has developed a patented method that compensates for internal battery resistance by creating two active modes, where the transition from the CC to the CV stage is controlled by a microprocessor allowing active control by monitoring actual cell voltage during the charging process. This functionality is achieved without a requirement for additional feedback signals. This subsequently creates greater allowances for the input charging voltage.