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jonbix asked

BMV-702 discrepancy vs voltmeter

My 702 voltage reading for both house and Auxiliary voltage reads more than 1 volt higher than my voltmeter shows. 702 readout = 12.82 voltmeter read out = 12.69 My fuse in the wires that run from the battery to shunt is 100 m amp. Can you help me fix the problem?

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2 Answers
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Mark answered ·

I assume that you mean >0.1V (not >1V)?

If you have a 100mA fuse in the BMV positive supply cable it can cause it to slightly under-read voltage (as there is some voltage drop over the actual fuse. But your having the opposite issue, so the recommended practice of changing it to a 1A fuse should actually increase the BMV voltage reading slightly.

I would firstly verify the voltage with another multi-meter that is calibrated/known to be accurate and to exclude any other factors ensure that you measure between the same points that the BMV is attached to (so between the negative on the shunt and the terminal where the BMV positive lead is attached.

Sometimes you can also tell if you have a bad multimeter if you measure with the +/- probes reversed, but the voltage reading is different, it should measure the exact same voltage but just have a '-' symbol if measuring the wrong way around.

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jonbix answered ·

Thank you. I obtained a calibrated fluke multimeter and found the voltage matched. All set now. Thank you again.

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Mark avatar image Mark ♦♦ commented ·

Great to hear - thanks for the reply!

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