question

joe6789 avatar image
joe6789 asked

Multiplus drops battery voltage to almost zero

Tried installing only the DC side of the Multiplus 2000 in an RV. If I connect only the Multiplus to my battery, it seems to run fine and the AC-out shows 110V difference. However, if I also connect my normal DC loads (e.g. lights, water pump), then the Multiplus will not even turn on because for some reason the battery terminal voltage drops to ~1 volt.

What is happening?

If I disconnect the Multiplus and hook up only my DC loads to the battery, the loads run well (draw about 1 amp) and the battery shows 13V across terminals. Or if I disconnect the DC loads and hook up only the Multiplus, then the Mutiplus runs fine (draws 0.7 amps at idle) and the battery again shows 13V. But when I hook up both the Multiplus and DC loads simultaneously, neither run and the battery shows 1V across terminals.

I'm thinking there may be an issue related to the grounds, since both the Multiplus and the negative battery bus bar are connected to the chassis, so maybe the grounds are interfering with each other.

Would appreciate any expertise here. Thanks!

Multiplus-II
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1 Answer
Justin Cook avatar image
Justin Cook answered ·

@joe6789, would you post a picture or two of your setup?

One thing I'll note is that the MultiPlus NEG should absolutely be connected directly to your battery, not the chassis... but I'm not sure that that would cause the issue you're seeing, so if you could post some pictures of the wiring that would be very helpful.

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