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I recently measured a brand new Duracell AA battery which is labeled as 1.5 V. The reading was 2.3 V. Is this ever normal for a fully charged battery, or is my multimeter broken?

Peter Mortensen
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merlin2011
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1 Answers1

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Most likely cause is that you need to replace the battery in your multimeter.

When the battery is very weak, the voltage drops to the point where the internal reference can no longer maintain regulation and it, in turn, also drops. A low reference voltage results in a high reading, which is exactly what you are seeing.

Usually there will be a low battery indicator in the display, but you may have not noticed. Personally, I think the display should be blanked rather than display an erroneous reading, but many meters do not do that.

Spehro Pefhany
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    I audited my half-a-dozen meters for low battery, when the warning comes on, when the reading goes bad, when the display blanks, and was horrified. If you have more than one meter, and a variable power supply, it's an exercise worth doing. The cheapo ones are not necessarily the worst! – Neil_UK Jun 06 '17 at 09:20
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    It is at low battery. I'll replace the battery and try this. Thanks! – merlin2011 Jun 06 '17 at 10:12
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    I have an analog scope that I was using to measure resistance but got different readings for the same resistor at different multiplier settings. Changing the battery also fixed that. – MichaelK Jun 06 '17 at 12:11
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    @Neil_UK It's like a twist on the clock saying: "A man with one multimeter knows what the voltage is, but a man with many multimeters is never quite sure" – W5VO Jun 06 '17 at 13:26
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    @W5VO I thought that was about compasses. – user Jun 06 '17 at 14:27
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    @MichaelKjörling, It is about measurement. Period. (but clocks are certainly oft mentioned.) – hildred Jun 06 '17 at 15:47
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    @W5VO When two of my meters disagreed by ~2%, and I wanted to charge some lithiums, I finally used a 0.1% reference to cal them, AD1580 was the best performance available in the tight-ar$e price range from CPC. Needless to say, I bought several of those! – Neil_UK Jun 06 '17 at 16:53
  • @Neil_UK: I wonder how much extra it would cost to make a multimeter distinguish between "Battery is good", "Battery will fail soon, but readings are still good", and "Battery insufficient for reliable readings"? I would think a modern ASIC could offer that feature while being cheaper to produce than one made using older technologies. – supercat Jun 07 '17 at 15:19
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    A man with two compasses placed close enough to each other almost certainly does not know which way North lies. – Solomon Slow Jun 07 '17 at 17:44
  • But please make sure that you don't use these 2.3V batteries for the replacement, and damage it.... – Henry Crun Mar 12 '18 at 04:06