First..
yes it's THAT bad.. and you could've seen that it is yourself if you finally stopped lurking for hp ratings and just used some very basic math (Volts* Amps = Watts[electric]) times efficiency (should be around 80% .. V*A*0.8 ~= Watts[mechanical]) to get the ideal mechanical power again in Watts.
(it's the first equation in the linked post
)
things like that are important to make a wise decision, that's why I asked you to forget about hp ratings in the first place.
Aaaanywhoo...
The ME0909 has a good standing amongst DIY EV builders, so I think it's generally something worth considering if it's in the price and power range you need.
I can't download the Datasheet (since I refuse to register at that site)
wich kinda is important as well..
since the website's description is again fishy to absurd
I can't imagine it's as bad as they announce it to be.
4hp rating (uhhh come on fellows.. stop using crap like that!!) (2942 Watts about'ish I'd say... IF that's metric hp)
Now, at the same "label" (i.e. continous) it say's 48V and 100Amps... 4800 Watts electric,
that's only 61% efficient...
I can't imagine that's it's sweet spot at all,
but to know for sure, you should take a look at the performance pdf linked on that site.
Personally I'd stay away from anything that's less than 75% efficient (which is the lower end of modern PMDC motors efficiency)
frankly, since you'll likely overshoot the motor at one point (you or some friend of yours test-driving it) be warned:
a permanent magnet DC motor can be rendered useless in very short order..
Everything bit of power that is not converted to mechanical forward momentum is converted to heat..
magnets are very sensible to heat, and if "cooked" for too long or too hot they lose magnetic strength very quickly
Say you buy a 5kW PMDC motor like that.. max 100Amps or 300 for 30 secs..
you install a slightly bad ratio just to have an extra theoretical mph on your speedometer...
and your buddy floors it uphill for a minute and a half
then, when he finally comes back moaning about the low power of the kart.. that motor isn't able to produce more than maybe 800Watts of mechanical power anymore (since the magnets are already deep fried into uselessness)
I don't say it will happen, but it surely CAN happen!
Motors even in that pricerange are to be handled with care and according to their capabilities.
But check the spec sheet.. see what it's efficiency really is,
and if you cannot trust yourself or your friends enough to guarantee you will never apply more than 100Amps for more than 30 seconds (usually per 15mins of driving time)
then.. DO NOT BUY a PMDC motor at all..
find a series wound motor. Yes; you can kill them too.. but not nearly as easily
'sid
PS and yet.. you still search for hp labeled motors...
