500w BPM kit from BMS Battery

[topographer]

I tried the 350w (same as 250w) BPM at 22A, 25A and 30A. There was no difference in the power and torque. 22A is the maximum.

So feeding it excessive amps doesn't harm it, it just has no benefit?

 

[Deleted member 4366]

So feeding it excessive amps doesn't harm it, it just has no benefit?

I only tested on short hills so I'm not sure what heating effect that woild have on long ones. I think the effect is called saturation. I don't know what effect that has on efficiency - whether it just limits the current getting through the windings or whether it causes heat. I think just the former. In a blindfold test, there was no difference detectable between the 22A and 30A controllers.

 

[Woosh]

a more useful test is power consumption when climbing long steady hills like rupert1 did with his woosh Bermuda

http://pedelecs.co.uk/forum/threads/france-on-a-woosh.28220/#post-382588

More torque means you climb at higher speed, therefore improving your motor yield, lower heat waste and therefore should give better battery consumption. You charge the battery to full, and check the battery voltage after the trip.

 

[John_S]

AFAIK, they also have smaller 15A controllers.

I didn't know that.
I could solder the shunt of the controller to increase the torque, although I'd have to be careful not to overdo it.

 

[topographer]

I think just the former.

Where would the energy go if not into heat?

 

[anotherkiwi]

I think in the case of saturation it doesn't go anywhere. The motor draws a certain number of Amps and ignores the rest even are available.

 

[Deleted member 4366]

Where would the energy go if not into heat?

That's the question. Saturation is when increasing the current doesn't increase the magnetic field, so the current still flows, maybe efficiently, but can't do anything.