Advice for someone looking for an ekit

[bunchofapes]

Hello all, just joined. hi!

The more i look at kits, the more i get confused and beffuddled

I have been looking at various sites and decided the most sensible way to go is to find a reputable dealer.. So probably woosh will fit the bill..

Looking at their site at the
Hubkit with 26" Bafang SWX02 rear Wheel

It quotes a Maximum power: about 500W.. this is on the 250w motor.. So im confused as to what that means..?

Can it be operated at 500w? How is that achieved?

I want something to take help with the hills on my way to work, so I don't have to sweat like gawd knows..

And that I can go reasonably fast on..

I understand the UK laws, but im a sensible rider, who would like the option of more umph on occasion.

Thanks all

 

[Nealh]

All 250w rated motors can output many more watts at the motor via the controller.
As an example we will use the SWXO2 though could be any good hub.
Controller rating is 17a, battery nominal voltage is 48v.
17a x 48v = 816 watts. The controller can output 816w max to the hub. Hubs are about 80% efficient using that power so 20% is wasted which still means the hub can output 652w in pas 5.
Don't worry about the watt output as long as the hub is marked 250w that is all that matters.

I use 20a controller with 48v battery and my lcd shows nearly 800w sometimes this is the power the hub is out putting and you can feel it for sure on the hills.

 

[sjpt]

Just clarifying as long as the hub is marked 250w that is all that matters.
The 250w marking matters for strict legal on-road compliance, but not for anything else..

Sadly most lower end controllers don't show current amps/power, so I don't know what we are getting under what circumstances. Any pointer to how the controllers work and what they to to protect motor overheating would be interesting (do you have one, Nealh?) We usually use level 2 or 3 of 5 on our XF07, 250w rated, 36v, 17 amp controller. I don't think that if we used level 5 it would try to deliver a constant 17x36*0.8=490w even on a hill. We would have gone for the SWX02 if it had been available in 700C when we ordered.

You could probably get the maximum by using full throttle; though I think the throttle is not technically road-legal on a conversion. I have read (maybe not reliable source) that the throttle sidesteps the controller, so maybe it could overload the motor used consistently?

 

[Nealh]

The 250w marking is a compliance that it has passed industry testing for the rating at a 1hr continuous test and doesn't over heat at that wattage output.
In the example below only in PAS 5 does it exceed 250w output.

In pas 5 the controller will deliver max amps much the same as the throttle will.
Each assist will give a % of amps = watt output.

The KT controllers give the following amp output as indicated in watts on a lcd3 or 6 display @36v 17a.
PAS 1 13% = 64w = 2.2a
PAS 2 20% = 98w = 3.4a
PAS 3 33% = 161w = 5.6a
PAS 4 50% = 245w = 8.5a
PAS 5 100% = 490w = 17a.

The lsw (Luishi controller) will be of a similar output.

The higher output isn't a continuous output as the motor would get to hot and suffer damage but it can handle the power as long as speed doesn't labour the motor. Generally half the speed of the motor is a good minimum speed so about 7 - 10 mph for most geared hubs.

 

[sjpt]

Note that Woosh have two versions of the SWX02 rear Wheel kit, a 36v and a 48v; both with 17a controllers. 36v near the bottom of page http://wooshbikes.co.uk/?hubkits and quoted as max 500w, 48v near the top quoted as max 750w. Neilh was assuming the 48v version.

Don't forget that it is total wh that matters with batteries, so the 48v 12ah battery has the same power as a 36v 16ah one.