Batteries

Reviving Batteries
Some batteries, especially those of certain chemistries, have the potential to be brought back to life. If a battery has not been used for a while, or a device has over drained it, the voltage of the battery might be below what the charger accepts. This will result in the charger not being able to recharge it. Be aware of the dangers working with battery recovery. A battery that has been over drained is most likely damaged permanently, and will never perform optimal again. If you use this method in combination with sales, make sure the customer is well informed that the battery is no longer operating at full capacity. The following methods are are applicable for single cell batteries. For multi cell batteries you may use these methods on the individual cells, but this bring in a whole new set of issues not dived into here at this point.

Method 1:

Connect the battery in parallel with a battery of the same type for a short while (about 5-10 sec), and check the voltage to see if it is raised enough for the charger to recognize it. Repeat until the charger recognized the battery. Note, this method is not recommended for higher power batteries.

Method 2:

Use a transformer set to a voltage equal to, or very slightly higher than the battery's rated voltage. Connect the battery and periodically check its voltage. If the voltage is rising, there is hope. Connect a very small load to the battery to drain the top charge (1 sec should do it in most cases). If the voltage continues to fall the battery is destroyed and should be recycled. If the voltage is stabilizing, repeat process until voltage is high enough for the charger to recognize the battery.