kiwifiat
100 W
John in CR said:Kiwifiat,
You're mixing facts with fiction trying to confirm a myth. It is invalid to compare two different windings at the same current, because the slow wind motor you're trying to say is better on hills cannot handle the same current as the speed wind. For the speed wind you simply lower the voltage and increase the current for the same power input and rpm, and then torque and efficiency will be the same, ie same torque and rpm and same amount of heat produced.
If what you myth promoters say was actually true, then speed wind motors wouldn't even exist. The torque limits of our hubmotors are set by the iron and the magnets, and have nothing to do with the copper. How the copper is wound only matters to the extent of the voltage and current you want to run. As long as the total copper is the same, then they can make an identical amount of torque for the same amount of heat loss in the copper. Saying that a slow wind motor makes more torque at the same current is irrelevant, because in that comparison the slow wind makes more heat to produce that greater torque. Apples and oranges comparisons simply don't cut it. Your understanding is incomplete, because you can't ignore copper losses.
The only ways to make a hubmotor better able to climb a hill does not include rewinding it with more turns on each tooth, which accomplishes nothing, because you decrease current handling by the same amount you increase the torque constant. Decreasing wheel size, and improving heat rejection are the only things that will help a motor climb hills better.
John in Cr,
I suggest that you teach yourself how to derive the torque equation for an electric motor from first principals. There are numerous resources on the internet that will teach you this. Equally there have been a large number of papers posted on this forum that confirm that the mathematical models used in motor design yield results that correlate extremely well with the real world testing of motors designed using those formulas. You are just spreading misinformation by maintaining the torque output of an electric motor depends on the iron,magnets and current alone. You might also consider the fact that the majority of e-bikes in the world are powered by batteries that are constrained in voltage and current which makes turn count an even more critical parameter in motor design.