LUP message on Inverter

Not sure what you meant by this.

volts ÷ wattage = amperage.
Amps × volts = wattage.

I think you missed the part where I said I used to be an electrician? I used to build compressor stations, SCADA stations, substations, sub stations and MCC stations.
I dealt with DC, AC, voltages at low as 9v and as high as 150,000. And amps as low as .002 and as high as 2565amp.

4awg cable is fine for use in an inverter. The only issue he may run into is if he ups his inverter size more, 3000w plus, and plans on running it all day, he may want to up his wire size to a standard battery cable.

His issue I still think is 1 or two bad batteries leading to the whole shebang going bad.

A lesson in batteries:

Your battery is filled with multiple cells each cell is responsible for 1.4, or 2.1 volts or some number like that, when each cell is charged they add up to 12.4 volts. Each of those cells also produces a certain amp rating.

As the electrolyte level drops in the battery the cells will still produce 12.4 volts when charged, but the charge is lower quality.

So battery at new charges at 12.4 volts 995cca, 2months later it may be 12.4 985cca, ect. At this rate when most people to a proper load test they disconnect each battery and test separately, that way the test is 100% accurate. Now MOST TECHS are lazy and uneducated and just hook up the battery bank and test like that.

Now that means during the load test, they are only looking at amps. The Entire bank may under load produce 1800ca but that's 4 batteries. It's a pass but it's all 4 included. That means that at charge the batteries at displaying 12.4 volts, but there is no power behind them, so when you apply a load, the voltage will quickly drop, even faster than the alternator can compensate when the engine is running. The inverter will detect the drop in voltage and throw a code to protect the batteries. Since the alternator has a charge detector that has a delay, that is how this happens.

Now once these batteries get to this point there is no saving them. They need to be replaced, as most of the new battery types are sealed and the electrolyte mix inside cannot be replenished.

I had a 386 with a similar issue, my batteries would pass a Peterbilt load test. I left and my truck wouldn't start no more than 3 days later. Had it tested at a TA in Indiana, watched him remove each battery and all but 1 failed. But combined they would have just barely passed. Easy way to see if your batteries are weak, start your truck, and apply a load to your inverter and watch the voltage display on the inverter. If it drops more than say 2 volts you have weak batteries.

Battery strength is measured in AMPS not Volts, but volts dropping quickly is the first.major sign of strength loss.

I was hoping I didnt have to explain all this.

 

What OP is exaplaning fits what I am saying perfectly, his battery cells are weak causing severe voltage drop. Under no circumstance should the voltage drop below 12v during use. The inverter is set up to detected that and shut off to protect the batteries and it's self.

I also want to say, I made a comment of your system being way to beefy. I was saying that in reference to the fuses and your actual inverter. Your cables are adequate for what you require of them.

Inverter cables and battery cables are used based on short period use, if you were actually going to use them 100% of the time the cables would fail. As most batteries have a 1000amp crank. You don't want to know how big a 1000amp cable is, yet the cable to the starter is only a small O/ cable.

 

Maybe you can help me? I have the yellow 3000 watt power Inverter from a love's. Per the manufacturer, I actually got the 000 awg wire. Not cheap, not light, not flexible! As I recall, I connected a 250 amp fuse directly to the battery and tethered the cable from it. I'm about to purchase something much sturdier and weather proof from a boat shop. I ran my 1200 watt microwave from it via a very heavy duty extension cord. It's NEVER been right!

TV works fine, vacuum works fine, other light duty plugs work fine. Sooooooo, I'm figuring the problem is the wire is too long, or the extension cord, as I've heard you can't plug a microwave in via extension cord.

I recently purchased a 3.1 cu ft fridge. I'd like to keep it on. Batteries are a year old. I clean all terminals after each winter by hand with wire brushes. I also want my microwave to work!

After recently cleaning the terminals and plugging in the inverter, it now says the LUP message. I believe I changed the wiring and ran off 2 different batteries, same bank obviously.

Help! Hahaha

 

Ok first thing that jumps out at me is this idea of sturdier and boat shop, for what?

Wire?

Second are these couple of questions ...

Do you have the cables hooked up to the battery bank or a single battery?

Do you have both cables on the batteries or one to the battery and one to the truck?

Have you been running the truck when the microwave is running?

The lup error means the inverter isn't getting enough voltage.