Drill charger battery problem

[Viking Mountain Tool Works]

I have a drill with two sets of batteries that is not working with either battery. How do I trouble-shoot the problem; is it the charger, the batteries, or the drill?

Scott

[Mike Henderson]

Most people have multiple tools that use the same battery system so you just take the battery to another tool and see what happens.

But if you only have one tool, given the information you provided, I'd suspect the tool. Most of the time, if the battery is left to rest, when you plug it into the tool, you'll get a small amount of action by the tool. It'll turn once or twice, slowly, and then quit. If it doesn't do that with either battery, I'd have to guess that the tool is bad.

Testing the voltage on the battery might give you an idea. If the voltage is up to spec, or even above spec, I'd say the battery is probably good, and charged.

Mike

[Steve Baumgartner]

As Mike says, the easiest and quickest way to identify the culprit is to find another tool with compatible batteries and do some comparison tests. If the other tool works using your batteries, your tool has failed. If you tool works using the other batteries and your batteries won't take a charge from the other charger, the batteries are dead. If all the cross-tests work well, your charger is dead.

If you don't have or don't know anyone who has a compatible tool, perhaps a friendly store will let you do the tests on their demo unit...

If it is the tool (typically worn out brushes or a bad trigger switch), look for a bare tool (i.e. one sold without batteries). These are available many places and usually cost less than half a new tool with a pair of batteries. That could actually be cheaper than fixing the dead one!

[Lee Schierer]

you can check the batteries with a volt meter across the terminals. You can get a digital multimeter at Harbor Freight for $6.00 that will tell you if your batteries are dead. If your batteries have a charge, then it is likely the tool.

[Mike Henderson]

you can check the batteries with a volt meter across the terminals. You can get a digital multimeter at Harbor Freight for $6.00 that will tell you if your batteries are dead. If your batteries have a charge, then it is likely the tool.

The voltmeter test can be misleading sometimes. The voltmeter takes very little power from the battery, especially compared to the tool. Sometime the battery will show a voltage on the meter, but as soon as you try to pull any power from the battery the voltage falls to a very low value. To test a battery with a voltmeter, the ideal situation would be to read the voltage with the battery under load - but that's usually not possible at home.

An alternate situation with a voltmeter is to check if the voltage shown is up to (and usually greater than) the specified voltage. So a fully charged 18 volt battery may show a bit more than 18 volts on a voltmeter, for example. Mine show a bit over 19 volts when fully charged and no-load.

Mike

[Steve Baumgartner]

The voltmeter test can be misleading sometimes. The voltmeter takes very little power from the battery, especially compared to the tool. Sometime the battery will show a voltage on the meter, but as soon as you try to pull any power from the battery the voltage falls to a very low value. To test a battery with a voltmeter, the ideal situation would be to read the voltage with the battery under load - but that's usually not possible at home.

An alternate situation with a voltmeter is to check if the voltage shown is up to (and usually greater than) the specified voltage. So a fully charged 18 volt battery may show a bit more than 18 volts on a voltmeter, for example. Mine show a bit over 19 volts when fully charged and no-load.

Mike

Once again Mike is correct. The battery internally consists of several cells connected in series (and sometimes also in parallel). A battery with a bad cell may show a voltage similar to a partially discharged good battery, but won't provide enough current to run the tool. However, a bad cell generally won't charge to full voltage, so you will usually see less than the rated voltage after a recharge. By the way, a good charger will detect a bad cell and inform you that the battery is defective.

[Walter Plummer]

Make sure the battery contacts inside the drill are clean. I cleaned up my Makita and it started working again.

[David Ragan]

A friend of mine is a battery guru. He has found his calling.

I asked Rod about shop tools:

-Systematically go through and charge each battery every month, whether used or not.
-Never let your Ni-Cad batteries run down all the way.

I do the above every 2 months, and keep piece of tape on each battery so I can put the date of last charge on it. So far, so good.