Inverters cut out at half capacity

[agrota21]

Now that the whole picture is uncovered (no proper design from the start), you could keep trying to thrash all the pieces into a solution, or, you could work with the customer to do the design work, and see what pops out at the other end. From that design, some or all of the current pieces then might fit (be reused) in the new design.

At the least, and just guessing because the design requirements aren't obvious, I'd say move to 24v or 48v inverter, being as someone thought they needed two 5kw 12v inverters. The good news is that you can assemble some beefy 24v or 48v battery-banks from the pile of 12v batteries.

Customer might complain, but that is a consequence of possible purchase before design ...

Yeah, the typical vehicular system is run at 12 volts so alternator charging can be utilized. The typical loads are around 1800 watts per inverter but one runs an rv style air conditioner...The start up inrush is the reason for the larger inverters. As much as I would like to up the voltage, this isn't really an option. I guess I don't understand why the Lifepo bank can't do the job when GC2s can with no trouble (except for run time). And yes, these are cheap batteries, so maybe it's a simple as that.

 

[Partimewages]

How long of time between fully charged and installation? Lifepo4 only loses 1-3% a month.

 

[Sanwizard]

Now that the whole picture is uncovered (no proper design from the start), you could keep trying to thrash all the pieces into a solution, or, you could work with the customer to do the design work, and see what pops out at the other end. From that design, some or all of the current pieces then might fit (be reused) in the new design.

At the least, and just guessing because the design requirements aren't obvious, I'd say move to 24v or 48v inverter, being as someone thought they needed two 5kw 12v inverters. The good news is that you can assemble some beefy 24v or 48v battery-banks from the pile of 12v batteries.

Customer might complain, but that is a consequence of possible purchase before design ...

I agree with your approach. Way too much current draw with this setup.

 

[Bleedingblue]

I highly doubt you have 13.2v DC at 190 amps load current at inverter DC input terminals.

There are guys who have 100,000 watt stereo systems that run 12 volt. They just run multiple runs of 1/0 wire (bunch of em), so no voltage drop. And around 1200AH of Cmax cells. Usually run around 5 -370 amp alternators

 

[Vigo]

Curious if this ever got resolved or new measurements. Sounds to me like the voltage measurement location was wrong enough to not pickup on the likely issue of serious cumulative voltage drop across the 1/0 feeds from inverter to bus bars, but also quite likely across the bus bars depending on how those were sized, how the lugs were hooked up to them, and where the meter leads were touching the bus bars.

I have a 5kw 12v MSW inverter in my RV which WILL start the rooftop unit with a ~300a startup surge. I generally don't the rooftop unit from that inverter as i installed a smaller secondary unit which is what gets used 98% of the time. But similar to the OP's statements, that's why it is the way it is and it does work. I have no reason to go away from any of it unless i have a serious component failure. It also allows me to add and remove mismatched batteries in parallel without much concern, as long as don't try to charge or discharge the entire pack at a highish C-rate. Other than briefly running the rooftop AC off the inverter (which would certainly result in a very imbalanced set of mismatched parallel batteries and connections), i can charge it and discharge it at lowish rates without really worrying about one of the mismatched batteries limiting the overall usable Wh to any significant degree. As fas i've noticed, anyway. Seems to work fine. So 12v gives me some upsides on flexibility in a system that was always partially treated as a sandbox to experiment in.