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hairyhaggis avatar image
hairyhaggis asked

BMV-712 not showing Solar input through redarc bcdc1225

I have a Redarc BCDC1225 connected to my starter & Aux batteries, with a red Anderson plug installed on the front bullbard, connected to the yellow wire on the bcdc. The BMV712 & shunt are installed in the back of the wagon, with the Aux battery wire connected to the battery side of the shunt, and the fuse block for my lights, USB, ciggie sockets wired back to the load side of the shunt. Everything works as it should for this, and I can monitor everything properly through the BMV when the accessories are drawing power.

Also connected to the load side is the starter battery, and the BCDC charger earth.

I have just gotten my solar panels, and hooked them up today through the red Anderson plug, and whilst the voltages of the batteries increased, I could not see any current in the BMV, it just showed 0. I had the solar connected and used something i know draws roughly 9 amps, and it showed a draw of -4A on the BMV, which means that at 1700, the panels were only putting in 5A, which would be about right. I disconnected the solar, and it went up to -9A, showing that there was solar input.

How do i get the correct reading on the BMV for this? Do i need to connect the Anderson plug negative to the shunt aswell?


thanks for any help!

BMV Battery Monitor
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2 Answers
klim8skeptic avatar image
klim8skeptic answered ·

To measure current, there has to be a path through the BMV shunt.

All loads and charge has to be placed on the load/charge side of the shunt.

The only wire on the battery side of the shunt, goes directly to the battery negative terminal.

All chassis negative wiring on the battery has to be moved to the Load/charge side of the BMV shunt.


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redarc.png (182.9 KiB)
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hairyhaggis avatar image hairyhaggis commented ·

Thanks Klim8skeptic, I've connected up the shunt as you have suggested, but still running into the same issue. Once I disconnected the starter battery earth cable to engine and chassis (as it came from factory) I could see minimal amps being put into the system, but not what the solar panel is producing. I put this back on for now, need some more info about disconnecting this, and if it is safe to do so. (this prob has bearing on not seeing any amps on the monitor when attached)


At the moment, I have a negative bus with the following attached: starter battery, bcdc, solar Anderson plug, and coming off of the bus, I have another cable that runs to the load side of the shunt, which has another cable from my rear fuse block on it. Only my aux battery is connected to battery side.


I have an earth wire going from my aux battery to the chassis to ground it all out. Does this need removed? How do I ground the aux battery if it is?


My bcdc has the solar icon lit up, and stage mode flashing. Will it not show me the total amps my panels are giving me, just what it is putting into the system to keep it topped up?

Pic attached is basically how the set up is at the moment


Thankyou!


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dual-battery-setup.png (235.0 KiB)
dual-battery-setup.png (235.0 KiB)
klim8skeptic avatar image klim8skeptic ♦ hairyhaggis commented ·

Thanks for the diagram. If you move the chassis earth on the aux battery to the other side of the shunt, that will work.

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hairyhaggis avatar image hairyhaggis klim8skeptic ♦ commented ·

Thanks mate, that's the aux earth to the load side of the shunt?

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klim8skeptic avatar image klim8skeptic ♦ hairyhaggis commented ·

Thats it.

NEED to learn paint (or something). :)

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redarc-b.png (185.0 KiB)
hairyhaggis avatar image hairyhaggis klim8skeptic ♦ commented ·

Hi Klim8, I changed it over, and that appears to have got it all working! Can see the Amps going in now - although ill need to wait to discharge the battery, as I was getting 11A from the solar (checked on the included PWM controller straight to the battery via alligator clips), but the BCDC was only putting in 2A as the Voltage for the battery was too high (I only discharged it about 3%), so bcdc was in absorption mode, then float, so didn't deliver the full 11A to the Aux.


Thankyou for the help!

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Trevor Bird avatar image
Trevor Bird answered ·

I guess you could just disconnect the Aux Battery ground connection because the load side of the shunt is already grounded through the start battery ground.


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