Is this a daft thought ?

[Ptarmigan]

If one had, say, a rear hub or crank drive bike and one were worried about running out of range on the battery, one could carry an extra battery of course, ok so far ,,

But how about carrying that extra battery already wired up to, say, a front hub motor ?
Not only would you have the battery already conveniently attached and ready to go but it would also be ready (double head in old steam loco parlance !) to assist on a steep hill ?

Ok, late at night, nurse,, fetch my pills ?? !

 

[Scimitar]

D8veh is already there with a twin-drive, but permanently connected.
Your idea would be fine if using them entirely seperately, but simultaneous throttle control is problematic if you try to use them uphill - d8veh cracked that with one unit common to both.
I suppose you could have one twist throttle for the rear and a thumb throttle for the front, but I would think it would be ... interesting trying to control them simultaneously.

 

[Ptarmigan]

>"D8veh is already there with a twin-drive, but permanently connected."

Ah so, link ? I am new here !!

>"Your idea would be fine if using them entirely seperately, but simultaneous throttle control is problematic"

I think I was thinking separate, perhaps only one on throttle and the other system on some sort of 'assist' type mode perhaps, I was kinda thinking aloud so all amplifications welcome, thanks

 

[Deleted member 4366]

San eagle has that.A Bafang SWX on the front and a Q128 on the back. Two separate controllers and throttles and one battery. The front motor works like normal with PAS and throttle with the PAS level set on the control panel, and then, when he needs more power for the hills, he uses the throttle for the other one.

I have two two wheel drives. One is high speed and the other is normal speed, but they're different to Saneagle's in that I have double throttles. Both Have PAS for the back motors, and when I use the throttle, it powers both motors equally. You can see photos of both my bikes in my profile photos. Both have twin Q100s. The idea isn't new, many have done it before us, and I'm sure that many others had the idea when they were strugling up a hill with a single hub-motor.

 

[Ptarmigan]

>"San eagle has that ,,, he ,,,"

links ? do you mean www.sanegle.com ? big site ,, !

>"The idea isn't new,"
I didnt expect so ! Out of all my ideas I only have two patents,(telecomms) and both of those were subsumed by my employer!
But at least you didnt shoot it down in flames as impactical like some of my other ideas have been

Is it legal ?

 

[Deleted member 4366]

No. It's Steve, my neighbour, who started with a standard Saneagle folding bike, which has been through many transformations that goes something like this:

Standard bike
Completely accessorised
Motor upgraded to BPM
Double battery arrangement
Completely stripped to essential components and motor back to original but with 22 amps and 12S lipos
Q128 motor added and 12aH Headway battery
Gradual re-accessorising,

Many of the components have been upgraded along the way: bars, forks, cranks, pedals. It's always been a nice bike to ride, and it's been a lot of fun doing all the changes. Many of the parts came from car boot sales, so didn't cost much apart from the Q128 motor and Headway battery, which add about £400 to the original £480 cost of the bike.

 

[Ptarmigan]

Thanks for all that, very interesting, and thought provoking

When I said "Is it legal" I was too brief and made me sound stupid as well as daft !
What I was thinking was : If one uses only one device at a time one would be within the spirit of the law. Is there anything in the law that excludes the fitting of more than one ?
Hmmm, I bet someone has fitted 3 somewhere
It's ok, just thinking aloud again, nurse will be here with the pills soon , , ,

 

[flecc]

If running both together would be under the rider's control, it's very definitely illegal to have two 250 watt hub motors.

Even if they could not be run together, the UK's EAPC law and the EU type approval law (which is a construction and use regulation) are clear that the bicycle motor(s) must not exceed 200/250 watts respectively, so arguably also illegal simply because they are both fitted and not luggage.

 

[Waspy]

If one had, say, a rear hub or crank drive bike and one were worried about running out of range on the battery, one could carry an extra battery of course, ok so far ,,

But how about carrying that extra battery already wired up to, say, a front hub motor ?
Not only would you have the battery already conveniently attached and ready to go but it would also be ready (double head in old steam loco parlance !) to assist on a steep hill ?

Ok, late at night, nurse,, fetch my pills ?? !

You can have one motor and two batteries if range is your concern, like this:

Used Electric Bikes - electric bikes and conversion kits

You can have two motors and two batteries for speed, but you would need a number plate, insurance etc. Like this:

Xipi Ghost

 

[jackhandy]

Hmmm, I bet someone has fitted 3 somewhere
It's ok, just thinking aloud again, nurse will be here with the pills soon , , ,

That would be front hub/rear hub/crank drive, then would it?

And why not?

Wouldn't want to pedal the beggar home, mind.....

 

[Ptarmigan]

Wouldn't want to pedal the beggar home, mind.....

Ah yes, good point, might need a 4th to get it all home ,,,
goes away to contemplate a trike+crank , ,