Chalo said:
Tommm said:
He is pushing 3.6kw, 40mph/60kph is nothing for that amount of power.
My quick check using the Kreuzotter speed calculator suggests that 3600W of
mechanical power to the wheel would only result in 42mph on level ground. So the fact that he's getting 40mph means he's doing really well with what is optimistically about 3000W after efficiency losses.
In this case, a faster winding would result in lower top speed unless there were more current available to push it.
For me on mountainbike setting at 3600w it says 48.6mph/78.3kmh.
40mph/60kph is what my legs can take me up to with a sprint with a bbs02 assisting me, and my toothpick legs certainly don't put out even 1kw.
krombopulos_michael said:
My controller has both a flux weakening and overspeed programable options. Right now the 3rd power toggle on my throttle is programmed for 110% speed and 100% current. I’ve never messed with the flux weaking parameter though because I’ve never been sure what it does. Could anyone describe what flux weakening actually does instead of saying that it increases top speed and decreases effeciency? By how much does flux weakening increase your top speed and how bad is it for the battery(how many more watt hours do you burn through)? Also what XPD program parameters should I be using to get the max speed out of my motor given that I only have max 84V to work with. If I can get my 4T motor near 48mph by reprograming the controller and adding ferrofluid to motor then I’ll be satisfied for now.
A lot of smarter people than me have wrote what it does on this forum, you can look it up, basically, if you are RPM and not power limited at the top speed (from my calculations for arguments sake let's assume it is the case
(it is)) flux weakening will change the the signals sent to the motor along with dumping even more amps into it, it will help you reach the power limit instead of the RPM one.
For example, if you have a motor geared for 25mph top speed, you will be using just 5A at top speed even with a 8A controller and battery. With flux weakening if you gain 20% RPM, a usually attainable number, you will go 30mph and draw ~8A.