question

dtronn avatar image
dtronn asked

Why is the Inverter negative VERY hot under a light ( less than 15A) load?

Im running a Dometic Brisk II AC unit pulling about 13.8 A startup--- strickly on battery power, (for now as an experiment) and after initial startup that amperage drops off to somewhere around 5.3 to 5.8 according to Dometic specs. Why does this amount of current cause both battery leads + and - bus bar to inverter (multi plus 12 3000) to become EXTREMELY hot (after 5 minutes I cannot hold it tightly, in a very calloused hand mind you ) additionally, why does the negative lead heat up and get much hotter than the positive lead? both leads are 4awg and less than 30" terminal to busbar...I havent tried using shore power yet... as I feel this is a dangerous situation that needs resolution first.... Thnak you all so much... IDK what I'd do without this community of experts...

Multiplus-II
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3 Answers
Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

My first guess is a bad/loose connection or a bad crimping at the cable lugs.

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dtronn avatar image dtronn commented ·
verified, torqued to spec with my wrench, crimped with mechanical crimping device, thanks.
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Stefanie (Victron Energy Staff) avatar image
Stefanie (Victron Energy Staff) answered ·

@DTronn

After all the problems in your other post yesterday, I highly recommend hiring a knowledgeable and trained professional to review your system. And please, before anyone gets hurt.

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dtronn avatar image dtronn commented ·
I appreciate your concern Stephanie thank you; I will look into a review, however my problem seems to have been a useage of the 12/ 3000 with their diagrams, while having ordered from a smaller set up.
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seb71 avatar image
seb71 answered ·

You don't have 15A on those wires.

You have something like 120A.

The 4 AWG (about 25mm2) battery wires are way undersized.

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dtronn avatar image dtronn commented ·
Thank you....exactly, leads should be a 4/0 ............NOT a 4awg.
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kevgermany avatar image kevgermany ♦♦ dtronn commented ·
Are you saying that 4AWG was a typo, or confirming that the leads are undersized?
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