Adding second motor to old Wisper bike?

[Chris Maluszynski]

Hi everyone,

After having test driven a total monster bike this summer (5000Watts!) divided between both wheels, I started playing with the idea of adding a front motor to my old Wisper Works (equivalent of 905).

Does that seem doable to those of you with experience of building e-bikes? How would one go about it? Are there controllers for two wheel drive?

Or is there an easier way of adding more power to the old wisper (not sure what the motor on it is capable of in reality, I suppose it may be stripped down to make it legal?)

By the way, it's not speed I'm after, but rather torque. There are many steep hills where I use the bike.

Cheers,

Chris

 

[Alan Quay]

It can be done, but I'd be surprised if it's worth it. You will probably need another battery and definitely anothr controller and throttle/pedal sensor.

D8veh has done it, but IIRC he had some problems keeping his face off the tarmac.

You would be better off buying a single, more powerful kit.

Alternatively you could solder the shunt for a bit more current and therefore power.

 

[Deleted member 4366]

It's as simple as it sounds. Just buy a front motor kit with a bottle battery, fit it, and away you go.

Two motors require two controllers. You can get bottle batteries with controllers in them, which makes installation simpler.

You can use a single battery to power both controllers, but it needs to be able to provide at least 30 amps for two motors, which rules out your Wisper battery and most bottle batteries.

I would set up the front motor with throttle only, so that you can ride normally with the rear motor and then bring in the front when you want to climb hills with the throttle. You won't get any extra speed by adding a front motor. 20 mph will be about the max if your Wisper is unrestricted. If you want more speed, you need to change the rear motor too, though I fitted a 328 rpm Q100 to the other wheel of a bike with a motor like yours. The combined motors gave good climbing power and the front one got the speed up to about 23 mph after the rear one had maxed out at 20 mph.Here's a photo of it. The original motor was in the front, so the back motor was added. In the bag are the two controllers and a 12Ah high discharge rate battery.

The single throttle can work both motors if you tie the two battery grounds together.You should fit the back brake to the rear motor's controller and the front to the front one.

 

[Chris Maluszynski]

Cool! Sounds simple enough.
If I'd only be using the front to climb hills occasionally: Could I get away with using one of the 4Ah Macallister batteries (famous from another thread) for the front motor?

Also: "Solder the shunt" - what does that mean? Sorry for noob questions.

 

[Chris Maluszynski]

Oh, and could one brake cut out both motors?
And one more: I suspect my Wisper is restricted, as it was bought from a store in Norway. Any way of "unrestricting" it, and if so, does that add more power/speed, or just the ability to throttle it without pedals?

 

[torrent99]

Also: "Solder the shunt" - what does that mean? Sorry for noob questions.

Keep us up to date on this please! I've often thought of doing the same to my Mk 0.9 Wisper 905se.

Solder the shunt, means opening up the controller and adding some solder to the large bit of wire (the shunt) that the controller uses to work out how much current it is using. If you thicken the shunt with solder, the controller thinks it is using less current than it actually is and so gives you more power....
All at the risk of frying your controller or wiring (& motor but less likely), and provided your battery can actually supply the required current.

 

[Deleted member 4366]

Solder the shunt means open up your controller and add some blobs of solder to the shunt in it. The aim is to cover about 25% of the length, which will give you a 25% increase in maximum current. Torque is proportional to current, so you get 25% more climbing power. Only do that if your battery is sound.

The Macallister battery might work. One will be pressed hard to provide the current of at least 15A. Two would be much better. Also, you'd be surprised how quickly a battery goes down during climbing, especially when it's sagging due to the high demand. Two decent hills could empty one.

The bit about the face plant was when I was using three motors for 5.5kw on a road covered in chalk, which had been rained on to make it slippery. My bike was so fast that the back wheel overtook the front one. I think Einstein said something like that happens when you approach the speed of light.

 

[torrent99]

Oh, and could one brake cut out both motors?
And one more: I suspect my Wisper is restricted, as it was bought from a store in Norway. Any way of "unrestricting" it, and if so, does that add more power/speed, or just the ability to throttle it without pedals?

If it's like my early Wisper there's likely an unused connector on the controller that you short (or unshort) to de-restrict it.

 

[Deleted member 4366]

One brake cutout can work both controllers, but it can be dodgy, better to use two cutouts with one to each controller.

If your Wisper is restricted, it would probably be easiest to buy a new controller with the rest of your kit. You should be able to get a better one.

 

[Chris Maluszynski]

What does it actually mean that it is restricted? Is max speed/torque limited? Or is it just the throttle control?

 

[Alan Quay]

What does it actually mean that it is restricted? Is max speed/torque limited? Or is it just the throttle control?

Normally its max speed.