On or Off-does it matter?

[Yannu]

Hi all,
wasn't sure where to post this so trying here, please tell me if it belongs elsewhere (is it Technical...?).
When riding I found I used assist on the hilly bits and turned off motor when I didn't need the help. However, did notice that if I left motor on all the time it went quiet during the bits where I didn't need help; presumably not doing anything. Sooooo, it sounds an odd question to ask: is there any difference between turning the motor on and off as you ride and leaving it on all the time? (when you don't need it)
Thanks in advance
y

ps picking up my new bike on Saturday. Woohoo))))

 

[Scottyf]

The reason the motor goes quiet is becasue the power being sent it from the controller is no longer creating peak torque. Its trying to create faster rpm.

The noise comes from the gears (If a hub geared bike) with plenty of torque passing through it.

There is a difference if you stop using power. If again a geared hub motor the clutch will disengage allowing the motor to freewheel. Which means less drag from you turning the motor.

After you get past the assist from the motor and keep the motor turning your are effectively turning the motor over with your legs to make it go quicker.

The below is a typical graph of an electric motor

The slower the motor goes the more torque is generated.
This graph applies to most electric motors with an unlimited amount of power (Controllers are there to limit current / speed etc)

 

[jerrysimon]

My motor tends to stop assisting after about 14-15mph, so I rarely engage it once I am around that speed.

Regards

Jerry

 

[kitchenman]

Hi Yannu, welcome to the forum. Your in the right place! .. I leave my assist switch on during my 15 mile commute. WHen I told my supplier he was a little surprised but indicated that it would not be a problem.

 

[kitchenman]

I'll be turning mine off when I don't need it in future! ...

 

[tillson]

Hi all,
wasn't sure where to post this so trying here, please tell me if it belongs elsewhere (is it Technical...?).
When riding I found I used assist on the hilly bits and turned off motor when I didn't need the help. However, did notice that if I left motor on all the time it went quiet during the bits where I didn't need help; presumably not doing anything. Sooooo, it sounds an odd question to ask: is there any difference between turning the motor on and off as you ride and leaving it on all the time? (when you don't need it)
Thanks in advance
y

ps picking up my new bike on Saturday. Woohoo))))

Is your motor of the crank drive type? I thought the Bosch, Panasonic and maybe the new Kalkhoff drives switched themselves off once that the max assist speed had been exceeded.

 

[wurly]

If you are talking about switching off the controller rather than not using the throttle, you aren't saving much. On mine it's about 40mA switched on not doing anything.

 

[Scottyf]

It will natually use less and less power the faster you go above the assist speed.
As you are powering the bike (and the motor) rather than the motor helping you.

Not using the throttle or the controller will save more battery than leaving it on. But not by much really.

When I had my old front hub motor I used to use the assist up to the speed required and then drop off the throttle and use my own steam to carry on past.
If I left the throttle on it would hinder my speed as I would be using my energy to rotate the motor.

 

[Deleted member 4366]

On my 250w front hub motor bike, I fitted a wattmeter to see what happened.:
As it approached 15mph, the watts (power) went gradually down until the y reached zero at about 15.5 mph. Above that speed, no measurable powerwas consumed, so in that respect it makes no difference whether you switch on or off. Some people tend to use their power only when there's a headwind or a hill to save battery and get a longer range.

If anybody hasn't got an on/off switch and wants one, you can use any on/off switch that you can mount on the handlebars. You only have to splice it into one of the brake switch wires, so that the controller thinks that you've applied the brake.You can still use the brake switch as long as you don't cut the wires.

 

[Jimod]

I have a rear hub motor. I leave it switched on all the time. The only time I take it out of the top power level is when I'm on a canal towpath. The motor just does its business and lets me do mine. It pushes me up hills and against headwinds, it even shoves me along when I'm tired and I pedal slowly. If I'm feeling fit I pedal above the cut out speed and the motor doesn't do much but as soon as I run out of puff the little chinese hamsters in my back wheel take over and all is good in the world. I can't see much point in me buying an electric bike and me doing the work.

 

[Yannu]

dear all,
thanks for the replies.
Sorry for slow response - sick children - haven't even had a chance to try out new bike yet:-(
E-motion Off road 650 for those interested (panasonic crank drive)
atb
y

 

[flecc]

In that case there is a difference, if you leave your e-motion switched on you will be using current all the time when pedalling below 15 mph.

Switching off when pedalling then saves current, but when either not pedalling or pedalling at over 15 mph, no current is used so there's no need to switch off then.