I know this is a stupid question but I just dont undertand......

KirstinS

Esteemed Pedelecer
Apr 5, 2011
3,224
899
Brighton
Why is it a problem if you just hook a battery directly to a hub motor with a simple on/off switch (i.e no controller). Even my daft self knows the asnwer wil be - the motor will fry

But here is the thing. My dad has one of those stand on electric scooters (15Ow 24v) that he uses for zipping around marinas. The 2 x 12v SLA inside packed up and so he bought 2 x 12v SLA usualy used for motorbikes (these are much larger and no longer fit under the deck but have greater AH). He simply strpped them to the deck

More interstingly he ripped out all of, what he termed "gubbins", and just hooked the batteries to the motor with an on off switch.

Has not blown up after nearly 6 months, goes about 30% faster and for miles and miles.

This I do not undertand !
 

rog_london

Esteemed Pedelecer
Jan 3, 2009
764
2
Harrow, Middlesex
Why is it a problem if you just hook a battery directly to a hub motor with a simple on/off switch (i.e no controller). Even my daft self knows the asnwer wil be - the motor will fry

But here is the thing. My dad has one of those stand on electric scooters (15Ow 24v) that he uses for zipping around marinas. The 2 x 12v SLA inside packed up and so he bought 2 x 12v SLA usualy used for motorbikes (these are much larger and no longer fit under the deck but have greater AH). He simply strpped them to the deck

More interstingly he ripped out all of, what he termed "gubbins", and just hooked the batteries to the motor with an on off switch.

Has not blown up after nearly 6 months, goes about 30% faster and for miles and miles.

This I do not undertand !
It's easy enough - almost all hub motors are the 'brushless' type, which absolutely require some slightly complex electronics to make them work at all. That's taken care of by the controller.

The motor on your dad's scooter is a standard DC motor with brushes - probably not a million miles away from a windscreen wiper motor, and low tech - and in particular it requires no electronics to run - you can just connect it to a battery. Of course without some control gear it's on or off and no choices in between!

It must be a bit hairy to ride with only on and off available....

Rog.
 
D

Deleted member 4366

Guest
He's lucky. I did that as well and I melted two motors. As you say it can work with some brushed motors, but not with the brushless motors that are used on most ebikes and some of the more recent scooters that use RC motors because they are three-phase and need a suitable controller.
 

flecc

Member
Oct 25, 2006
53,559
30,848
Essentially, the brushless motors that are mostly in use now are incomplete, the rest of the motor is the controller, performing the function the integrated brushes used to on the older motor type.
 

KirstinS

Esteemed Pedelecer
Apr 5, 2011
3,224
899
Brighton
thanks - that makes perfect sense to me now

It is quite an old scooter (6/7 years) so prob has the low tech brushed motor type that you mention.

He is only 5.6 and very slight - certainly under 10 stone. Maybe that helps prevent burnout

And finally, yes - he said it is indeed quite hairy, he tells me you have to really lean forward on take off to prevent wheelies !

Still it makes me think that for short range DIY fun an old brushed hub wheel could be bought of ebay (I think maybe powabyke had brushed?) and a 12v battery. As long as you only engaged the motor once alread doing a decent pace it might be alright.....might be fun to find out anyway !
 

KirstinS

Esteemed Pedelecer
Apr 5, 2011
3,224
899
Brighton
sorry I meant 2 x 12v

And sorry again as I know my suggestion goes against all the quality parts and proper engineering ethos that most folk here ascribe too. And most sensibley too :) !
 

rog_london

Esteemed Pedelecer
Jan 3, 2009
764
2
Harrow, Middlesex
He is only 5.6 and very slight - certainly under 10 stone. Maybe that helps prevent burnout

And finally, yes - he said it is indeed quite hairy, he tells me you have to really lean forward on take off to prevent wheelies !

!
He strikes me as the sort of game old bird (no disrespect intended) who should be joining this forum! Obviously he doesn't let the grass grow under his feet.

Rog.
 

Orraman

Pedelecer
May 4, 2008
226
1
A brushed motor can be switched on and off to allow a measure of control of speed and power.

One model of the TGA Electrobike had a trigger switch on the handlebar as did the Zeta but the results on the Zeta might not be felt.

Electric winches of 1.1 Kilowatt are used to launch F3B model gliders by pulsing the switch to control the power.

If the bicycle was pedalled up to a reasonable speed before switching efficiency should be good.

Dave