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eseidman avatar image
eseidman asked

Wiring for BMV-712 and Airstream

battery.JPGAsked on FB, but didn't really get answers... I have two black cables from the battery, one is 4-gauge that goes directly to the built-in 1000W power inverter and one is 6-gauge that goes directly to the busbar in the electrical box. See pics below. I think I need to connect these two black cables to BATTERY ONLY side on the BMV-712 and then run similar sized black cables back to where they are currently connected. Correct?

battery.JPGas-elect-box.jpg

BMV Battery Monitor
battery.jpg (4.5 MiB)
as-elect-box.jpg (3.3 MiB)
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pwfarnell avatar image pwfarnell commented ·
Your battery photo shows another cable connected to the left hand battery negative which you have not labelled or listed. This should go to the system side of the shunt as well to ensure that any current flow through it does not bypass the shunt, the only connection on the battery is the shunt, nothing else.
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eseidman avatar image eseidman pwfarnell commented ·
I think that might be from the Zamp port that I plug my portable solar panel into... maybe. Still move it?
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pwfarnell avatar image pwfarnell eseidman commented ·
Yes, because if you do not, when you use your portable panel the charge amps will not be counted going back into the battery.
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eseidman avatar image eseidman pwfarnell commented ·

Thanks!! So do I need to make any changes with the wiring to/from the SunExplorer II solar charge module?

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pwfarnell avatar image pwfarnell eseidman commented ·

If the solar connects direct to the battery negative then it needs moving to the system side of the shunt. The rule is simple, the only thing connected to the battery is the shunt, every other connection goes to the system side of the shunt, solar, inverters, system loads, chargers and any chassis ground.

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eseidman avatar image eseidman pwfarnell commented ·

And any reason I cannot just connect the Power Cable for the BMV-712 to the busbar with all the red cables in the pic below, or does it really have to be connected directly to the battery?

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pwfarnell avatar image pwfarnell eseidman commented ·

It can go to the bus bar, it is slightly less accurate voltage if there is some voltage drop.

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1 Answer
Kevin Windrem avatar image
Kevin Windrem answered ·

Move those two cables from the battery negative to the system/load side of the BMV's shunt. Run a single wire from the shunt's battery terminal to the battery negative. This should at least be of equivalent size to the 4 + 6 gauge wires. From an ampacity chart I found online it looks like that means 1/0.

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eseidman avatar image eseidman commented ·

Got it! Thanks! So do I need to make any changes with the wiring to/from the SunExplorer II solar charge module?

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