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dabus avatar image
dabus asked

BMV 712 showing negative discharge when charging

Hi all. I have a new installation of lithium house and AGM chasis. I added the BMV 712 to the system with wires connected as per diagram and pictures found here. The BMV 712 is reading a discharge(negative #) current and watts when charging and a positive current and watts number when disconnected from charger and a load on the house batteries. Could the data cable of the 712 be corrupted or the PC board have a glitch?

BMV Battery Monitor
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3 Answers
simen avatar image
simen answered ·

Switch your shunt around.

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heidi avatar image
heidi answered ·

Page 13:
https://www.victronenergy.com/upload/documents/Manual-BMV-700-700H-702-712-EN-NL-FR-DE-ES-SE.pdf

2.3 Common problems

Charge and discharge current are inverted Charge current should be shown as a positive value. For example: 1.45A. Discharge current should be shown as a negative value. For example: -1.45A. If charge and discharge current are inverted, the power cables on the shunt must be swapped: see the quick installation guide.

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dabus avatar image
dabus answered ·

Thanks for the info. I switched the cables and now it reads negative on loads but when charging from solar I am still getting a low negative AH drain, not reflecting the High amps going in from the solar.

2 comments
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Justin Cook avatar image Justin Cook ♦♦ commented ·

@DaBus you most likely have a system negative (such as the negative from your charge controller) bypassing your shunt. ALL system negatives, including loads, chargers, and chassis grounds, MUST be connected to the "loads and chargers" side of the shunt. The ONLY thing that may be connected to your battery negative is the "battery" side of the shunt.

Please thoroughly review the user manual for more information on proper connection, programming, and operation.

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Robert Bennett avatar image Robert Bennett commented ·

Was having the same problem. Moved my negative on my solar to the shunt and bingo!

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