A piece of rechargeable nickel-metal hydride battery temperature and terminal voltage will gradually increase with the battery charge, the battery is fully filled and began to decline. Therefore, the main task of nickel-metal hydride battery charging is to detect this sudden point and interrupt the charge, or from fast charge to trickle charge. In addition, the continuous monitoring of temperature and voltage during charging can also provide system safety.
    In addition to the monitoring function, the NiMH battery charger also has an internal timer that sets the maximum charge time by connecting the external resistor to the TMR pin to set the fast charge time to 0.5 to 10 hours. The float time is set to half (0.25 to 5 hours) of the maximum charge time. In fast charge mode, if the maximum charge time is exceeded, the charger will switch from fast charge mode to float mode and reset the timer. The timer starts counting the float process, and if the preset float time is reached, the charger switches from float mode to trickle mode.