Unbalanced loading of the two motors doesn't appear to cause anything overly complicated like you mention. It would be impossible in all practical respects for one motor to drive the other because even if they are unbalanced, both will be torqued below their no-load speed all of the time. They would have to be really far out of balance for this not to be true. And, it would be easy to test for this. If both motors are drawing above their no-load current anytime during operating, then they are adding torque to the drive system.
That being said, the motor/torque speed curves do seem to not be matched perfect, especially when running motors in opposite directions to each other. This makes balancing them with current draw a challenge because it seems to change with speed. For example, I balanced my motors at <20 amps and low speed first, but this didn't cut it, and one motor got quite a bit warmer than the other one after a ride. So I tried balancing at a higher load and higher speed. It still didn't work. The best method for balancing the motors I've found is using temperature as feedback. Go for an average ride, then measure the temperature of both motor's rotor. Adjust the timing of one or both until the temperature is balanced after a ride. This will ensure maximum safety too, because heat is what causes things to fry. Regards, Andrew in NM On Sun, May 4, 2008 at 7:52 PM, Chris Tromley <[EMAIL PROTECTED]> wrote: > This brings up a question I've had regarding dual-Etek EMs. (Keep in mind > I'm an electrical dolt, so don't be afraid to set me straight if I need > it.) I'm guessing here, but I think vertical bumps aren't likely to loosen > a key. > > My understanding is that PM motors want to run at one speed and only one > speed at a given voltage. If the load increases it doesn't slow down, it > just draws more current. So if you have two Eteks driving the same vehicle, > being fed from one controller, any slight difference between their > volatage/speed curves will cause one to drive the other. Furthermore, the > two voltage/speed curves might cross, meaning one motor might be driven at > low speed and be the driver at higher speed. > > Seems to me torque reversals are more likely to loosen a key. > > Or not. I'm guessing. Does anyone have experience that can > proove/disproove this hypothesis? > > Chris > > On Sun, May 4, 2008 at 9:35 PM, dale henderson < > [EMAIL PROTECTED]> wrote: > > > I've got temp tags for second bike and i started taking it on test > > drives, i took it out for a 20 mile trip [ slowly breaking in the batteries > > ] but had a mechanical issue 5 miles from my house. the bike was behaving > > oddly so i pulled over to check it out. i have two motors [eteks] and the > > key for motor shaft on one motor sprocket fell out, i got another [hardware > > store near thankfully] and drove home. > > > > thus far the bike is great, but the hardtail is a bit rough [it shook > > out a key!] however the 'break-down' got me thinking about the advantages of > > a too motor system, namely i could still drive it with one motor, but i > > started thinking about it more and made a little thought experiment that > > i'll lay out in an accompaning email, feel free to give feed back on it. > > > > > > harry > > > > Albuquerque, NM > > http://www.austinev.org/evalbum/1179 > > http://geocities.com/solarcookingman > > > > ------------------------------ > > Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try > > it > > now.<http://us.rd.yahoo.com/evt=51733/*http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ> > > > > >
