Can a cmos battery be tested with a multimeter?

March 19, 2012 at 23:07:42
Specs: Windows XP
Can a cmos battery be tested with a multimeter? I have some batteries in some old boards, and i need to determine if there is a good one, for an old system i am fixing up. I am trying to avoid buying a new one to save $7. I would like to test them, my multimeter is analog, with a needle, and it has settings for testing AA, AAA, D, C, 9 volt as well as voltage, resistance, etc.

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March 20, 2012 at 00:14:30
Yes, Just connecting the voltmeter leads to the battery will give a no-load response but that's good enough for those batteries. Just test them all and whichever gives the highest reading will be the best one. They usually work down to about 1 volt but look for one that's at least 2.5 volts if you don't want to replace it again in a month or so.

If your meter has setting for battery testing I believe they provide a small load but I've always used the DC voltmeter setting and a range for whatever is appropriate for a 3 volt battery.

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March 20, 2012 at 01:35:55
A battery tester has too great a load for coin cells. A cmos battery can last more than 5 years so the current consumption is in the microamps.

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March 20, 2012 at 03:44:59
Hi Mark,

above advice is good, however with these coin cells often being only for 3 volts it is difficult to be precise when to discard.

e.g. a new 3v battery might show 3.3 v, whereas a used one 3.1v. I have experienced a car remote key would not work with the used one installed, but fine with the new one.

Am surprised at the price you quote, although you have not advised for which battery. For example, here in the UK, a blister pack containing 8 mixed (CR2016, CR2032 etc.) batteries costs £1.

As a matter of interest, where are you based? I am in Hammersmith, West London.

Good Luck - Keep us posted.

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Related Solutions

March 24, 2012 at 15:24:10
Generally silver batteries are very stable though out the life of them, Any amount below a normal new voltage would be suspect.

You never want to test batteries with resistance or amp's settings. They can blow up in your face.

As above the only correct way is to set a load on the battery for a timed test to see how well it can deliver voltage under load.

A Pit Bull is like a gun you can pet. And there is no safety on it.

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March 24, 2012 at 16:00:53
The proper load for a cmos battery is quite high. I would consider 1000 ohms per volt a minimum.

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