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Using a multimeter and set it on 200V DC - that's the lowest on this meter.

Tested a 1.5V and it reads 2.8

Tested a 3V and it reads 6.

Just replaced the battery.

The meter is ETEKCITY.

Any suggestions?

dashman
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    Buy a different meter? Is 200VDC really the smallest range? Can you post a picture? – Justin Sep 14 '20 at 15:04
  • Well I'm measuring a 3V CR2032 battery - it says 3V on it. Yes 200V is the smallest - 200 and 500. I can see some inaccuracies but 2x - most probably something wrong with the meter. Time to buy another cheap one. – dashman Sep 14 '20 at 15:19
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    And if you measured 0 volts it might read 1.3 volts - that's an absolute error of infinity or, relative to full-scale, an error of 0.65%. It's a numbers game. – Andy aka Sep 14 '20 at 15:24
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    Replaced the battery. With a new one? Cheap multimeters read high when the battery is too low. – winny Sep 14 '20 at 15:50
  • @dashman: What model of multimeter? [This one?](https://www.amazon.com/gp/aw/d/B07DW681FQ/ref=dp_ob_neva_mobile) – JRE Sep 14 '20 at 16:17
  • @dashman - Hi, Now that [your answer](https://electronics.stackexchange.com/a/521526) has explained your DMM was set to measure AC volts, not DC volts, and you were seeing about 2x the DC voltage, here are previous related questions where *some* (not all) answers explain the reason for that behaviour: "[Measuring AC voltage from DC battery](https://electronics.stackexchange.com/q/101418)", "[Why does a multimeter show VAC on VDC](https://electronics.stackexchange.com/q/52408)", "[Wrong multimeter readings measuring 12V lead acid battery](https://electronics.stackexchange.com/q/31147)". – SamGibson Sep 14 '20 at 20:42
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    Now we know you were measuring a DC voltage, using the AC voltage range of the DMM, then this existing question provides a good answer to explain that behavior: "[Measuring AC voltage from DC battery](https://electronics.stackexchange.com/questions/101418/measuring-ac-voltage-from-dc-battery)". Voting to close this question as a duplicate of that one. – SamGibson Sep 14 '20 at 20:52
  • This may not have been the best question, but it was a good learning experience, and you figured out what was wrong. Upvoted for realizing the issue, but also voting for the duplicate closure, as unsurprisingly this is not the first time this has been reported. – Chris Stratton Sep 14 '20 at 23:06

3 Answers3

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enter image description here

Figure 1. A comparison with an analogue meter. 1.5 volt will barely move the pointer and any reading will have little precision.

A 200 V meter is not a suitable instrument for measuring a 1.5 V cell. The resolution isn't available at the accuracy you require. Digital meters have specifications for error typically as a percentage of full scale ± a couple of digits of the display. That's what you're seeing.

I've never seen a "multimeter" that had a minimum V DC range of 200 V. For low voltage measurement you'll need a more versatile meter.

Transistor
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Please disregard my question.

I had the multimeter on AC voltage - duh!

I posted this also for other newbies running into the same issue.

I've added the correct symbols to look for in the image below

enter image description here

Now why in AC it reads double of what it should be in DC - there should be an interesting reason.

Thanks guys.

dashman
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  • Just gave this a try and can confirm a somewhat similar result. Likely it's a side effect of the method used to estimate RMS voltage when measuring an AC source, in the unexpected case where there's no sinusoidal variation. Also interesting is that I get *no reading* with the leads reversed! If someone wanted to have some fun, they could try pulsing a DC source at various rates, or researching how common meters *actually* do the measurement and math. – Chris Stratton Sep 14 '20 at 19:25
  • dashman - Hi, Regarding: "*Now why in AC it reads double of what it should be in DC*" You can't ask questions in an answer. However I have linked some previous questions above, where *some* answers to those (especially [this one](https://electronics.stackexchange.com/a/101422/101852)) explain why you can see approximately 2x the DC voltage, on some DMMs, when measuring a DC voltage using the AC voltage ranges. – SamGibson Sep 14 '20 at 20:51
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    @SamGibson - if that "i can't answer within a question" was serious. My "answer" was really I was a boob and had it in the wrong setting. Everyone can stand down. Re the question within the answer - I was just curious and thanks for the link. – dashman Sep 14 '20 at 22:19
  • I don't see this as asking a question so much as explaining what happened and admitting that the precise reason why this mistake gives this reading is unknown. **This is a valid answer as it resolves the asker's issue**, but yes, closing the question as a duplicate of another where it has been previously observed and where there may be more explanation is appropriate. – Chris Stratton Sep 14 '20 at 23:07
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    @dashman - Hi, Regarding: "*if that "i can't answer within a question" was serious [...]*" Actually I said the opposite - don't ask *questions* inside an *answer*. Why? (a) It breaks the SE model, where Q and A are in their own places; (b) Where should someone answer a new question, asked within an answer? In a comment? No, that is specifically discouraged - an empty comment box says "Avoid answering questions in comments". So what about writing another answer? No, because answers must answer *the original question*. That's why asking questions in answers is very problematic. Hope that helps! – SamGibson Sep 21 '20 at 20:15
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if the minimum voltage range is 200V, the precision is a bit lower in your test range. the catalog should mention the resolution in every range. and there are a few calibration pots on the multimeter board if you open it up, and if the manufacturer deisignates them to find out which one controls which parameter.

I searched up etekcity and it seems they make a few applicanes and ordinary things, but not precision things.

Tirdad Sadri Nejad
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