Single-cell NiMH batteries will occasionally begin to die. At times, it is possible to revive those batteries. If batteries are overused and the voltage falls below 1.0 volts, the battery charger can no longer recognise the battery.
Touch the clips of the DVM multimeter to both ends of the NiMH battery to check the voltage. If the meter reads lower than 1.0 volts, then it may be saved.
Connect the battery to the 12-volt DC 0.5-amp AC adaptor. Plug the adaptor in and charge the battery for three seconds.
Test the voltage again with the DVM multimeter. The meter should read at least 1.2 volts, or it is completely dead and cannot be revived.
If the voltage reads at least 1.2 volts, then place the battery in the traditional battery charger and charge it fully, about eight hours.