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How to Fix a Milwaukee 12 Volt Battery

Follow simple instructions and you can fix your 12 volt battery.
Hand yelow drill isolated image by Marek Kosmal from Fotolia.com

Milwaukee produces a large selection of cordless tools powered by a variety of batteries. Tools that require less voltage to operate are fitted with a 12 volt battery that contains either nickel cadmium (NiCad) or nickel metal hydride (NiMH) cells. Both cell types produce 1.2 volts and are wired in series, so a Milwaukee 12 volt battery contains 10 cells. If they are not regularly fully discharged both types of cell can start to lose power over time. However, it’s easy to fix this problem.

Place your Milwaukee 12 volt battery in the battery charger and let the battery fully charge. Turn off the charger and insert the battery into your power tool.

Secure your Milwaukee 12 volt battery and power tool in a vice. Run the power tool for some time until the battery is fully discharged.

Turn on the power tool and allow it to operate continuously until it runs out of energy. The power tool and battery will become hot during this process.

Turn off the power tool once it stops running. Let the power and battery cool down for about 1/2 hour.

Turn on the power tool and (although it stopped 1/2 hour ago) it will operate again. Leave it running until it stops again. Turn it off and let it cool down for about 10 minutes.

Turn on the power tool again to see if it operates. If it does, let it run until it stops and repeat the entire process again. Once the power tool doesn’t run, your Milwaukee battery is fully discharged.

Remove the power tool and battery from the vice. Remove the battery from the power tool. Let it cool down completely.

Put the battery into the charger and let the battery fully charge. It will take considerably longer to charge this time because the battery has been fully discharged and this breaks down the crystals in the cells. Once the crystals are broken down, they are able to hold and retain more energy. Your battery will last longer between charges and have more power.

Turn off the battery charger and remove the battery. Put your fixed Milwaukee 12 volt battery into your power tool, which is now ready to use.

Things You'll Need:

  • Battery charger
  • Vice


If you find there's little or no improvement after you've followed the steps above, consider purchasing a new battery. However, it may be worthwhile repeating the entire process one more time since occasionally it takes longer to fix the battery.

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