Rechargeable batteries are a popular and cost-saving choice to power tools, games and appliances. Unfortunately, even rechargeable batteries have a life cycle and eventually fail to hold a full charge. You can fix rechargeable batteries once they fail to hold a charge, making them last even longer. Bring your dead rechargeable batteries back to life by "zapping" them 1.
Discharge your rechargeable batteries completely so the "fix" for your dead rechargeable battery works on the entire battery charge memory 1. Run the rechargeable battery down in an appliance, game or tool through regular use. Certain electronic equipment such as cameras provide an option to discharge your battery completely.
Find the negative and positive nodes on the rechargeable battery. The positive end will be raised, and the negative end should be flat.
Place the black clamp from the 12-volt, 5-amp AC-DC charger onto the negative end of the battery.
Use the red clamp and tap the positive end of the battery three times. Sparks may emit from the battery during this process.
Hold the red clamp on the positive end and black on the negative end of the rechargeable battery for no longer than three seconds.
Release the clamps and check the charge level on the battery using the battery tester. If the battery is not fully charged, repeat steps 4 through 7.
Tips
Protect your skin, eyes and hair with safety glasses and insulated clothing during this hazardous process. The recharging process is best performed by someone familiar with working in electricity.
Warnings
If mishandled the battery can catch on fire, explode or spray acid. Individuals attempting this process need to understand that they are performing this process at their own risk and need to guard against damage to self, property and others.