the ones from a cooler will work to some degree. i rigged one up with a 12vdc cooling fan on it. after the cooler is cold, it gets to 24f at 75f outdoor ambient, and i disconnect it from the 12vdc, the fan will continue to run for about 5 minuits or more, although slower, all on its own from the temp differences. doe or somebody stacked up a few hundred of them on a tractor trailers exhaust pipe, and were able to eliminate the vehicles alternator, gaining another mile or so per gallon.thats about 100 amps or so, 5-10 would work for me. they also used new parts and spent about $10,000 on the project.