Being able to touch the motor's *outside* doesn't tell you much about the inside, especially on a geared hub. It can be quie a lot hotter at the stator and magnets than it is on teh case. A DD hub is easier to tell, but still can be very different.
gensem wrote:Is the Fusin much dif than a MAC?
Dunno. Most geared motors are very similar in basic design, but some details could be drastically different--enough to work in one application while another might not. Supposedly Fusin has improved their motors even more since mine was made (they offered a test/review unit of the new type to me but I can't afford the shipping).
The major design flaw in geared motors a year ago were weak gears that would strip very easily.
The major problem in a hill climb doesn't have a lot to do with the gears stripping, but with overheating because it can't conduct the heat out fast enough.
Gears can still strip if you apply enough power suddenly enough, or do that often enough, but unless they actually melt from the heat of the hillclimb, they probably won't break just because of the power itself, unless the hillclimb is really rough and requires lots of sudden bursts of power.
Lets pretend you ll be using 88v 20a in each hub, at that power level its nearly impossible to overheat the mac if you doing 20mph and up.
But you are not using 20A (battery current) if you are at 20MPH on the flats, probably not even 5-6A.
88V x 5A = only 440W, and it could probably take that all day.
However if you have a 20A battery current limit and do a hill climb, you will pull at least 20A *all the time*, probably, and that's 1760W at 88V (assuming no sag and full throttle). I doubt the motor will take that for the whole climb, *and* you will probably not be at 20MPH either--you'll be lugging slower, and the motor's phase currents will be a lot higher because it is unable to reach a good speed that it can keep them low.