How to Restore a NiCad Battery

Updated February 21, 2017

As you use nickel-cadmium (NiCad) rechargeable batteries and continuously recharge them, they hold less and less of a full charge over time. Within the rechargeable batteries a dendrite crystal substance, also known as battery charge memory, builds up and decreases the charge capacity. Eventually, when the rechargeable battery no longer holds a charge, the dendrite crystals have built up. To repair NiCad rechargeable batteries, you need to remove the dendrite crystals using an electric current.

Locate the black and red clamps on the trickle charger.

Test the NiCad rechargeable battery to make sure it is fully discharged.

Locate the positive and negative ends of the NiCad rechargeable battery.

Protect your eyes, hands and skin before beginning the rechargeable battery "jump start" process. This is a dangerous and hazardous procedure.

Hold the black clamp on the negative end of the battery.

Tap the red clamp on the positive end of the battery one or two times. Sparks may crack from the end of the battery.

Immediately hold the red and black clamps on the battery for 1 to 3 seconds only.

Use the battery tester or multimeter to determine the battery charge.

Repeat the process until the battery is fully charged.


Do not overcharge the battery or it may explode, catch fire or spray acid.

Things You'll Need

  • Dead rechargeable NiCad battery
  • Trickle charger
  • Digital multimeter or battery tester
  • Protective eyewear
  • Protective gloves
  • Long-sleeve shirt
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About the Author

Deb Katula has written and researched for Societe Generale, FIMAT, Nikko Securities, Chicago Mercantile Exchange and Arthur Anderson. She holds an MBA in economics and finance from the University of Chicago; a Japanese language fellowship from Harvard; and a Bachelor of Arts in business/psychology/Asian studies from Augustana College.