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by devin
05 Mar 2018, 17:11
Forum: General
Topic: General questions
Replies: 12
Views: 2286

Re: General questions

i made a comparison chart of 1 motor set to 57a max motors amps as previously described [24v battery, 0.05ohm winding, 1.5:1 gear reduction, 90mm tire, 190kv], and 4 identical motors set to 14.25a max motor amps. in theory the riding performance should be almost indistinguishable, but with 4 motors ...
by devin
04 Mar 2018, 14:52
Forum: General
Topic: General questions
Replies: 12
Views: 2286

Re: General questions

& as rew says, if you change the assumptions I chose from 3:1 to 2:1 gear reduction, then by my calculations and factoring the wind you can reach somewhere between 20-25 mph (32.1-40.2kph) before the wind drag force exceeds the thrust force from looking at the middle, top row chart. http://tppsf...
by devin
04 Mar 2018, 14:23
Forum: General
Topic: General questions
Replies: 12
Views: 2286

Re: General questions

i agree with rew if you lower the gear reduction to 2:1 or increase the battery voltage, then 15mph should be possible, but using 3:1 reduction, 90mm tire, 24v battery, then I believe (as rew seems to confirm) 15mph would not be possible. I do have a question for rew... what happens if he uses 3:1 g...
by devin
03 Mar 2018, 20:54
Forum: General
Topic: General questions
Replies: 12
Views: 2286

Re: General questions

Subject : Electric skateboard 1. I bought this motor: https://diyelectricskateboard.com/collections/electric-skateboard-motors/products/electric-skateboard-motor-6355-190kv and I also have a 6S lipo battery, does it enoght to bring me to 15 mph? I will now give you my opinion whether the board you ...
by devin
02 Mar 2018, 20:56
Forum: General
Topic: Vesc in ebike
Replies: 5
Views: 1169

Re: Vesc in ebike

22.247448v PWM Effective V * 22.47448a Motor Current = 500w electrical = 13.88a battery amps * 36v (22.47448a Motor Current * 22.47448a Motor Current) * 0.1ohm = 50.51022w ohmic Heating (@ 2000rpm, assuming 100kv, 13.88a batt limit, 70.71a motor limit) 2.146154751251963931499 newton meters torque *...
by devin
27 Feb 2018, 17:45
Forum: General
Topic: Vesc in ebike
Replies: 5
Views: 1169

Re: Vesc in ebike

devin just told you how to turn your motor into a 500 W heater. Don't listen to him. First: Motor current is proportional to motor load. If you don't put a load on the motor it will not draw a lot of current. In what situation did you measure the motor current? Second: The 1.5 A and 1.7 A you menti...
by devin
27 Feb 2018, 10:39
Forum: General
Topic: Vesc in ebike
Replies: 5
Views: 1169

Re: Vesc in ebike

my understanding is this... for example If you want 500 watts at all rpms... Step 1: Detect the winding resistance with the vesc, then double this number because the Vesc detects the resistance from one lead to the center of the motor (virtual ground point), but you want to know the resistance from ...
by devin
07 Feb 2018, 19:06
Forum: General
Topic: Calculating motor heating?
Replies: 4
Views: 825

Re: Calculating motor heating?

thanks. any tips on calculating or estimating iron/core loss? switching loss? what are the factors I should use to guesstimate? once i have an estimate for core loss and switching loss, is that subtracted from the mechanical watts or added to the electrical watts/battery amps, etc? do my above calcu...
by devin
06 Feb 2018, 20:11
Forum: General
Topic: Calculating motor heating?
Replies: 4
Views: 825

Re: Calculating motor heating?

Also, if I have an electric skateboard with a 50v battery, and a 90kv (90 max rpm per volt no-load) hub motor which is 0.1 ohm lead-to-lead, and a reprogrammable VESC electronic speed controller.... & in the reprogrammable settings for the electronic speed controller, my friend chooses the follo...
by devin
06 Feb 2018, 20:09
Forum: General
Topic: Calculating motor heating?
Replies: 4
Views: 825

Calculating motor heating?

I wanted to calculate the joule heating while the motor is in motion and putting out mechanical watts (before calculating iron loss). Are my calculations correct? If I have a 90kv BLDC hub motor which is 0.1ohm lead to lead, a 50v battery, ESC with 20a motor amp limit, 20a battery amp limit, present...

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