Inverter fuse popping with A/C

enblethen wrote:
If this is the unit it takes 8 amps at 115 volts.
LG 8000
Roughly ten times for 12 volt input would be 80 amps.
You overloaded input!

yep!

can you tell I'm a novice at this?

so the full story:
I bought a swamp cooler. It didn't work at all because the humidity is too high here. Returned it. Bought the LG. Didn't really do the math fully...made too many assumptions.

I'll start with a new fuse.

Also have a another battery on my list for this summer.

Thanks all for the rapid feedback.

It's all very much appreciated.

RoyB wrote:
A typical 1500WATT INVERTER will need to be fed from your battery bank using 4AWG CABLE with at least an inline 150AMP DC FUSE. 2AWG CABLE would probably be better... I would keep the length of the 12VDC HOT and GND CABLEs to less than five feet long. This information should be in the installation manual.

When the 1500WATT INVERTER is fully loaded down it will draw around at least 121 AMPS DC CURRENT plus inefficiencies.

The Air Conditioner will have a pretty good surge before starting up.

The two AGM 12VDC batteries in parallel will have 250AHs capacity but you need to check the battery specs on how long the battery bank will produce 12VDC at the 121 AMPS draw to know how long the air conditioner will run before discharging the batteries below their 50% capacity...

INVERTERS are known to be battery hogs big time...

Roy Ken

Thanks Roy Ken!

I didn't realize it would need a 150amp fuse! I only had a 30 amp in there. The wires are 4awg and are exactly 5ft long.

If this is the unit it takes 8 amps at 115 volts.
LG 8000
Roughly ten times for 12 volt input would be 80 amps.
You overloaded input!

A typical 1500WATT INVERTER will need to be fed from your battery bank using 4AWG CABLE with at least an inline 150AMP DC FUSE. 2AWG CABLE would probably be better... I would keep the length of the 12VDC HOT and GND CABLEs to less than five feet long. This information should be in the installation manual.

When the 1500WATT INVERTER is fully loaded down it will draw around at least 121 AMPS DC CURRENT plus inefficiencies.

The Air Conditioner will have a pretty good surge before starting up.

The two AGM 12VDC batteries in parallel will have 250AHs capacity but you need to check the battery specs on how long the battery bank will produce 12VDC at the 121 AMPS draw to know how long the air conditioner will run before discharging the batteries below their 50% capacity...

INVERTERS are known to be battery hogs big time...

Roy Ken

Thanks again.

So, an updated inverter should help?

The wires are: 4AWG Battery Cables -- they are big. I can't imagine having to go bigger.

That's a mod-sine inverter (msw), and not a very expensive one. Sorry, but I think you're going to have to go pure sine and spend a bit more to get the results you want. And your wiring should be in the 0 to 0000 range. A/Cs can surge to twice ( or more) of their rated watts to start. Yes, another battery or two would help.

I think your inverter is overrated, but, before condemning it too harshly I'd get bigger wires as a start.

thanks for the quick reply.

that's what I was thinking.

The fuse is on the 12v side (30amp fuse).

I think they are 4 gauge wires (could be 6).

Windy Nation Vertamax inverter.

I am also concerned about how long it will run and may add a 3rd battery to help...unless it keeps tripping the fuse. ;-)

Sounds like the startup surge is too much for it. What make/model inverter? Is this fuse on the 12v side? What size are the 12v wires?

I don't think just 2 batteries will run that very long.