question

svtriumph77 avatar image
svtriumph77 asked

How to wire a solar charge controller so the BMV-700 reads the solar input charge current?

I have a BMV-700 BMS that has done a great job and registers the incoming battery charge current from the shore power AC charger. I just installed solar with a MPPT solar charge controller that is clearly charging the batteries as the voltage goes up (as shown on the BMV-700 and the solar charge controller). However the solar charge current does not register on the BMV-700 which means all the SOC, Ah left, etc. does not work for the solar charging. Please help.

Solar Panelwiring
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1 Answer
Justin Cook avatar image
Justin Cook answered ·

@svtriumph77, the battery-out NEG from your MPPT is clearly bypassing the BMV-700's shunt; most likely you have it connected directly to the battery. The battery-out NEG from the MPPT needs to be connected to the "loads" (sometimes labeled "loads and chargers") side of your shunt, as the BMV uses the shunt to read current in/out of your battery bank and when a load or charge source NEG bypasses the shunt, the BMV can't see it.

While you're in there re-wiring the MPPT Batt NEG, double-check that you don't have anything else bypassing the shunt either. There should be only one thing connected to your battery NEG, and that is the "battery" side of the shunt; all other system NEGs including all loads, charge sources, chassis grounds, etc. must be connected to the "loads" or "loads and chargers" side of the shunt. Do that, and your BMV will be back to basically perfect accuracy again!

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