I was running a hammerdrill (13 amps full load)with my AIMS 5000 watt inverter for about 45 minutes with about a 80% duty cycle. It ran fine for that hour and then the AIMS 5000 quit. Since the AIMS says it is thermally protected and overload protected, I assumed that it had overheated, and some overtemp thermal breaker had opened, and that after a while it would start running again. It took several hours, but it actually did start running, but now it will only run for about 5 minutes, even with no load, and then it shuts down again. What do I need to do to fix it? Thanks, Steve

You have overstressed the Output devices, in the unit, this is a very common thing, they are "Damaged" generally, they use some sort of FET switching, semiconductors, and those transistors have become damaged due to large, continuous, gate current drives on their gates, this cause ablation between the Drain & Source, or equivalent, layers, this, increases the internal resistance and that causes then to go into runaway state very quickly, they self oscillate and eventually will totally destroy themselves if the same conditions apply. These need to be replaced, they will have to be replaced on Both sides of the Output drive. You see electromagnetic devices are NOT really the best to use on a device like that, really you need some sort of Motor generator/Alternator, and NOT a semiconductor switching unit, Inverter, you see an Inverter like you have is really only suitable for Electronic things, it is NOT really suitable for things that must generate magnetic fields, IE: Motors, heating elements, Electromechanical devices, as the reflections and spikes given out and back by the rising and collapsing magnetic fields, soon saturates the Driver Semiconductors, and will cause them to fail. Whenever you wish to power something like that, you MUST use a generator, or an Alternator, and that will work OK, as they have little electronics, on the Output, it is more sinusoidal, and drives magnetic, motor, and electromechanical & heating devices, much better. You may be able to run those devices, BUT only for say, 5 to 10 mins at a time, with a large period between uses, and even then, it will still eventually succumb, if used like that.
You will have to get a Service Manual, to have any chance of effecting a repair. Also obtaining the Output semiconductors and possibly driver semiconductors too, will be difficult to source, I would suggest the manufacturer direct.

The internal overload needs changing. The units are not meant to supply that much power for so long.

Not only will you cause damage to the invertor, but your vehicle's electrical system (alternator) is under tremendous strain.

THanks!!