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Les Rollins avatar image
Les Rollins asked

BMV 700 giving unusual voltage readings

Hello

We have bmv 700 battery monitor fitted on our narrowboat it's been situated on the boat for about 3 years without any problems. But just recently the BMV 700 and mppt controller battery voltage readings have differed greatly when using the blootooth to read them both. The bmv 700 does not show the correct battery voltage either when a genny or the engine is running it remains at about 12.80v where before it used to show 14 v or thereabouts. I'm thinking the pcb on the shunt may be at fault for the incorrect readings. Can anyone help please

BMV Battery Monitor
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3 Answers
Mark avatar image
Mark answered ·

As a first step I would recommend to verify the voltage at the terminals on the shunt PCB with a multimeter.

If it matches the BMV reading then it's the wiring/connections/fuse leading to it. If not then I would look at the UTP cable & it's connections next.

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Les Rollins avatar image
Les Rollins answered ·

Just wondered how I can test a victron inverter / charger. When the genny is on and if the batteries are low the fan on the charger kicks in and also the mikuni heater picks up speed. The genny is running stuff on the boat ie microwave, washing machine etc but it may not be charging the batteries the batteries might be getting there power from the 960 watts of solar only

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Mark avatar image Mark ♦♦ commented ·

Yes if loads are very high it's possible for no charge to flow into the batteries - even the solar could be going directly into powering the load (using the power assist feature of Vicron MultiPlus).

This will also occur more easily if you have a smaller MultiPlus or if you have the AC In current limit set lower than the max (because you have a small generator).

The only way to know what is going on is to look at the current screen on the BMV to see if the are positive or negative Amps into/out of the battery. Positive means charging & negative means depleting.

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ishtiaq avatar image
ishtiaq answered ·

a same issue here

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