[scrotty]

Imagine a situation where I want to future-proof my kid's kart. He is 7 now and I don't want him going more than, say, 14 mph. But in a few years 18-20mph might be okay.

If I got a 36v 1000W motor and a programmable controller (e.g. Kelly) could I program the controller to run the motor at lower speed/power? I'd be hoping that in that trade-off my amp-hour usage would also go down so my batteries would last longer.

I suppose another way to ask it: can a higher power motor be run as if it was a lower power motor - with all the same trade-offs in performance and efficiency?

Or should I just buy a smaller motor now - maybe a 36v 500W - and then in a couple years upgrade to a 48v 1000W motor.

TIA!
Sean

BTW- I realize that much of speed is related to gear ratios and tire size. For the sake of this question I'd like to focus on how much a "smart" controller can, well, control.

[Saintmythi]

what i would find to be the best root is get a controller like curtis or kelly that is like 24 - 60v or a yk43b. run it at 24v and if you want more speed and power run it 36v. i hate 24v no power if your over 100lbs. and than 48v when you want the full 2750rpm. same motor same sprocket everything stays the same.

hc is 48v 1k watt unite motor. i ran yk43b on 36v was great could climb a wall but only at 6mph. with full 48v i go 9ish. this is with a stock mx350 rear and a 11t front.

[scrotty]

Thank you, Saintmythi. It sounds like a big part of the equation is the RPMs that the motor runs at at a particular voltage. Does that mean that the current draw actually increases when undervolting a motor, making it a battery hog?

[Saintmythi]

yes unused power gets lost along the way, that you will never see out of the motor. i ran hc 48v motor on 36 and it lasted forever. was very slow but had the power to climb a wall. no joke, the little engine that could. i warn u the yk43b will burn unites quickly unless you have a way to keep them cool like open air and heat-sink.

[aidanworthington]

These are my results/calculations for a unite 36v 1000w motor


24v = 2066rpm @ 24.6 amp at this voltage id set the controler to 45 amp
36v = 3100rpm @ 35amp at this voltage id set the controler to 45 amp
48v = 4133rpm @ 49.3 amp at this voltage id set the controler to 38 amp
60v = 5166rpm @ 62 amp at this voltage id set the controler to 27amp

If the motor was geared to 20mph at 36v here are my speed calculations
at different voltages using the same ratio.

24v = 14 mph
36v = 20 mph
48v = 26.6 mph
60v = 33.3 mph

I hope this helps lol