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maxtosea avatar image
maxtosea asked

Why am I getting Low Battery/overload light on the DMC?

So Everytime I use my air conditioner on battery (4x330ah lifepo4) I get a low battery/overload light for a split second when the compressor kicks in. Batteries show way above 13.5v

System has 2x 12/2000 multi in parallel so I can't see 50amps from the air con overloading it. Plus I'm using a soft start.

It doesn't happen when I'm on generator or shore power.

Anybody have advice on what's causing this?

low battery warning
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1 Answer
kevgermany avatar image
kevgermany answered ·

Startup or inrush current of a compressor is much higher than normal draw.

You can look at inrush current limiters if it's a concern.

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maxtosea avatar image maxtosea commented ·

I thought that's what the soft start does? Also why wouldn't it happen on genset or shore power?

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Alexandra avatar image Alexandra ♦ maxtosea commented ·

@MAXTOSEA

Is doesn't happen on shore or generator because the power source is different.

From battery (inverting) you are likely getting DC ripple hence the overload low battery lights.

Have you daisy chained the batteries or are they all on a bus bar?

What size cable do you have? Do you have good tight connection snon fuses etc.

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maxtosea avatar image maxtosea Alexandra ♦ commented ·
The installer Daisy chained them. I believe it's 6 gauge wires. Haven't checked the fuses but I did check the cables going into the inverter and they are tight.
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maxtosea avatar image maxtosea Alexandra ♦ commented ·
So what can I do to prevent this from happening?
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davefromnl avatar image davefromnl maxtosea commented ·
To me it seems to have all 4 batteries daisy chained through 1 set of 6 gauge (less than 16mm2 for the not AWG using crowd) is cutting it a bit thin. 2000VA at 12V is about 160A. Per multi. So for high continuous loads it should be at least 0 gauge. You will probably not have the continuous load, so going adult forearm with the cables is a bit too much. But I think the quickest solution is to split the battery into two banks, each with a connection to the busbar. Preferably with something bigger than 6 ga. This might prevent the voltage dropping so low at the AC start that the low battery warning comes on.
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kevgermany avatar image kevgermany ♦♦ maxtosea commented ·
To expand on @Alexandra 's comment.

When on generator or shore power the batteries aren't driving the A/C, the multiplus(es) just passes the power through, so no battery warning. Large load on batteries will drop the voltage and cause the alarm.

If there's a soft start, it should be checked or upgraded.




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