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Apologies if this is off-topic.

I was given a used standard cordless 12v drill and 2 batteries, without the battery charger. The drill didn't work at all with one battery, and just turned slowly for about 2 seconds with the other, so I assumed the batteries were flat and so ordered a new charger.

However, this didn't seem to work. Having got a replacement charger to eliminate that, I found it still doesn't work. I assume it's the drill that's the issue, but it could conceivably be the batteries.

What do I need to do to test the batteries and drill with a multimeter?

  • 4
    Batteries die, a lot more often than drills do. I would reverse your default assumption. Typically, people get rid of old cordless tools when the batteries go, because the cost of replacement batteries quickly approaches that of buying a new tool. – BMitch Jun 13 '13 at 11:37
  • There are places that replace the individual cells inside the batteries fwiw. – Evil Elf Jun 13 '13 at 13:50
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Testing batteries with a multimeter

  1. Charge the batteries for a bit (follow the manufacturers instructions for the recommended charge time).
  2. Set your multimeter to a low DC voltage setting.
  3. Touch the black probe to the negative terminal on the battery, and the red probe to the positive terminal.

If the reading on the multimeter is at or above the voltage listed, the battery is good. Otherwise, you'll want to replace the battery (Don't forget, many home improvement stores offer battery recycling).

  • Just a note: Most 12V power tool systems are actually 10.8V nominal. They may read 12V immediately after charging, but once put under load they'll drop to 10.8V. Article with explanation here. Same goes with 18V vs 20V Max. – Doresoom Mar 11 '16 at 22:35

protected by Community Dec 19 '18 at 3:08

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