So we agree then that if you want to increase the top end speed you can switch from Single to Double?

That was the core point...


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Your analysis of current requirements doesn't take into account the way things often exist in the ebike motors. Very few ebikes seem to optimize for efficiency and instead tend to want to allow more current so that there is more torque.

For example:

The Unite 1200 watt motor is designed to run at about 48 volts and 40 amps. That tends to produce an inefficient powerband shape compared to the ideal. When you do like I'll be doing and switching from a Double to a Triple it will allow the powerband shape to get closer to the ideal while maintaining the same current limit.





What about hub motors?

Well... some are actually pretty close to being efficient right off the bat and modifying them might not make much sense. In the case of the Crystalyte hub motors they've done their best to present how to get them to run as well as they can. (they seem to be the ones that people use the most)

I'm a big advocate of geared ebikes that run the motor through the gearing and that allows me to do things like change gear ratios and stuff like that. However, even the hub motor might be able to use this rewiring option if the person is restricted somehow. The Optibike is generally known as the most sophisticated ebike in existence right now and it runs the motor through the gears.

Example:

Let's say you live somewhere that the laws say that the controller is more or less "fixed" at some level like 250 watts. If you replace the controller and get caught you face some legal issues. However, if you kept the stock controller (that in concert with the stock hub motor only gets you to 15 mph) you could rewire the motor to get you to 30 mph and there would be no visible sign that you were breaking the law. In fact, the power output would be the same only it would get spread out more.

The simple fact of all this... is STILL that rewiring really does work as a way to increase speed. You lose low end torque just because of the shift in the powerband alone (not even taking the Litz Effect into account) but you do end up with more top end speed and with the Litz Effect maybe it's just slightly better than before. Then on top of that you have the potential for better efficiency because you are in effect correcting the way many motors are designed to be used.

The core point remains... you can buy more batteries and overvolt to go faster or you can rewire your motor to make it go faster. The number of "Turns" defines the motor speed and the number of "Winds" defines the resistance and also (so the experts say) has some effect on the distribution of power in the powerband. I personally do not know if this "Litz Wire" will contribute a 5%, 10% or 15% difference in the shape of the powerband... but I'm curious enough to want to try it and see.

The nice thing about changing the number of "Winds" with the same gauge wire is that you can just buy one spool of wire and try it out. If a Triple turns out to be too much, then I can just rewire back down to the Double.

All the numbers point to the Triple allowing me to be able to use less heat in producing my peak power.

Heat = I^2 * R

Heat = ( 40 amps )^2 * 0.310 (Stock resistance) ---> 496 watts @ peak power

Heat = ( 40 amps )^2 * 0.103 (Triples resistance) ---> 165 watts @ peak power


Why does this happen?

Because the Stock motor configuration isn't the most efficient, so there is room for improvement. An "ideal" motor cannot be improved upon, but most motors do NOT run in their most optimal condition and tend to be favoring low end torque.



Re-Volt or Re-Wire?

That is the question...