Cordless tool battery repair

Original Poster: ADSM08

Difficulty: 3 out of 10

Time to Complete: 15 minutes. I did it while making dinner and playing fetch with the dogs.


Disclaimer: The Ranger Station.com, The Ranger Station.com Staff, nor the original poster are responsible for you doing this modification to your vehicle. By doing this modification and following this how-to you, the installer, take full responsibility if anything is damaged or messed up. If you have questions, feel free to PM the original poster or ask in the appropriate section of The Ranger Station.com forums.

Additionally you are dealing with a battery and heat. BE CAREFUL. Do not allow the iron to sit on the terminal longer than needed.


Brief Explanation: This is how to repair terminal connections on cordless tool batteries that may have been damaged. This applies specifically to the Snap-on 14.4V High Output battery, but may work for others as well.

In the case of my battery it would operate intermittently. Smacking it would make it work for a little bit, but it rarely stayed working for more than a few seconds. It was damaged after being dropped.


Tools Needed:
- Appropriate sized torx or screw driver
- Soldering iron
- Voltmeter


Parts Needed:
- Solder





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Steps 1: Open battery case. There is usually screw access from the bottom. The holes may be hidden under the sticker.






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Steps 2: Identify the damage. This can be done by using a volt meter hooked to one tool terminal and the sides of the individual cells. Move from one to the other until you don’t read power.



In my case the solder points of the positive terminal had been damaged by the initial impact when I dropped the gun, and then broken completely by the vibrations of the tool.



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Steps 3: Solder the damaged connector back together. Given the safety issues involved in soldering directly on a battery I made a big solder booger and flung it onto the counter to make it flat. Then I pulled the terminal up, stuck the booger under it, and held the iron on the terminal until the solder melted.



I did not take pictures during that part of the process for safety reasons. This pic was taken with the iron cold and unplugged.

Use your volt meter to test the battery across the tool terminals to make sure the repair is complete.
Then allow the solder to cool and put the battery case back together by reversing the process for disassembly.

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Nice write up. That's a common problem with batteries that have terminals like that. Cant even begin to tell you how many i had to fix when I used to rebuild batteries at work. And for anyone thinking about doing this do not ignore the safety issues mentioned in step 3. The way he described is the best way to secure the terminals if you dont have a spot weld machine.

interesting, i think have a battery kicking around that wont take a charge. thanks ad

Best part it, that battery would maybe work for 20 seconds at a time before. I used it all day today without a problem.