Is the displayed motor power output accurate ?

[StuartsProjects]

Bafang rear hub motor, 36v 250w, LCD3 display, KT36ZWSRD controller.

The display shows the motor power in watts.

At assistance level 1 and travelling at around 12mph on good level ground, the motor power is showing as circa 84W.

Now if that figure is accurate and with a 36V 10AH battery that equates to 4.2 hours of travelling or 50miles.

So, in general, is the motor power displayed likley to be accurate ?

 

[Nealh]

Bafang rear hub motor, 36v 250w, LCD3 display, KT36ZWSRD controller.

The display shows the motor power in watts.

At assistance level 1 and travelling at around 12mph on good level ground, the motor power is showing as circa 84W.

So, in general, is the motor power displayed likley to be accurate ?

Yes not far out.
In PAS 1 with my KT at 48v I see about 95 - 120w.

 

[StuartsProjects]

Yes not far out.
In PAS 1 with my KT at 48v I see about 95 - 120w.

OK, thanks.

Its kind of useful to be able to work out in your head whilst your riding, how much the various terains affects the approximate range, i.e. if 85W = 50miles, then 170W = 25miles etc.

 

[vfr400]

Bafang rear hub motor, 36v 250w, LCD3 display, KT36ZWSRD controller.

The display shows the motor power in watts.

At assistance level 1 and travelling at around 12mph on good level ground, the motor power is showing as circa 84W.

Now if that figure is accurate and with a 36V 10AH battery that equates to 4.2 hours of travelling or 50miles.

So, in general, is the motor power displayed likley to be accurate ?

Not at all because it doesn't show motor power. Instead, it shows the power coming out of the battery. The motor efficiency varies between about 0.3 and0.75 depending on how fast the motor is going and how much power you're giving it, so if you see say 500w on the display, the motor output power could be anywhere between 150w and 375W, but you normally only see 500w when the motor is going slowly, where efficiency is low.

Your 100w would translate to about 70w motor power.

 

[StuartsProjects]

Not at all because it doesn't show motor power. Instead, it shows the power coming out of the battery. The motor efficiency varies between about 0.3 and0.75 depending on how fast the motor is going and how much power you're giving it, so if you see say 500w on the display, the motor output power could be anywhere between 150w and 375W, but you normally only see 500w when the motor is going slowly, where efficiency is low.

Your 100w would translate to about 70w motor power.

So in reality the display is showing battery power output, wonder why its not labeled as such.

 

[sjpt]

So in reality the display is showing battery power output, wonder why its not labeled as such.

If you are interested in more details of what vfr400 said above look at https://ebikes.ca/tools/simulator.html
It might not have your exact combination of battery/controller/motor, but should give a very good idea.

This doesn't answer your question. It would be very difficult to display real power output; the display would need to know most of the details that go into the graphs on that website. Even then I suspect it would be pretty inaccurate due to variations of motors in the same batch, different temperatures, etc. The display of power taken from the battery should be pretty accurate.

 

[vfr400]

The power display on the LCD is like a fuel consumption gauge on a car. Its purpose is to help you ride with more efficient use of battery power. It's showing you how fast the battery is draining. That's much more important than telling you how much power the motor is making.