Combining controls from two motors

[danpenn]

I'm planning on adding a 500 watt front wheel motor kit to my bike that has a 750 watt rear wheel motor. With two batteries, two controllers, and two throttles. I'm thinking of having one brake sensor go to each controller for simpler wiring. Or should I have both brake levers talk to both controllers?

 

[addertooth]

There are diagrams on the web for doing this task. I haven't looked into them to verify. But there is no functional reason (I can think of) why the brake "switch" cannot go to two "identical" controllers. If they are mis-matched, then one may provide a different voltage to the switch than the other controller, which could cause problems.

 

[danpenn]

Thanks

 

[TwoTired]

Another thing to watch out for is the polarity of the brake signal. Most are active low, but there are also some active high. Some controllers have separate connections and can accept either one, check the controller specs.

 

[danpenn]

I think I will go with my alternate plan. The right hand brake will go to the original rear motor controller and the left hand brake will go to the new front wheel motor controller. My conditioned response braking move is to grab both brake levers.

 

[kmccune]

some are even combined any way, some people actual prefer a throttle without any brake cutoffs, you just have to be aware, the thing is always have good brakes and you can find dual motor controllers on ali baba or ali express,when you are building and having fun the sky is the limit

 

[m@Robertson]

@danpenn take a look at this. 2wd dual-hub ebike. Each brake lever connected to both motors. Twin hubs 750w each axle, and one 35a controller per axle. Single battery. Dual throttles.

Dual Motor AWD Electric Bikes – Case Study: Twin Geared Hub Commuter

A big bruiser geared specifically to be pedaled hard at 32-34 mph, this is my commuter workout-workhorse. Don’t want to sweat? Just relax and pedal easy… at 28 mph.

talesontwowheels.com

You want dual throttles, and I go into detail why in the other articles in the series. Particularly the initial explainer.

You can cross-connect your brake cutoffs with Y plugs. I did this with custom cabling but there are now plugs and extensions you can use so you can buy the parts and simply fit them together rather than order a custom cable with just the right HIGO, branch lengths etc. etc.

I would stay away from the dual-motor controllers. From what I have seen they are junk compared to a proper roll-your-own solution.

 

[m@Robertson]

Another thing to watch out for is the polarity of the brake signal. Most are active low, but there are also some active high. Some controllers have separate connections and can accept either one, check the controller specs.

For something like Magura brakes you will see a version that is an opener (aka Normally Closed) and a closer (aka Normally Open). Refers to the circuit at rest. So a normally open circuit needs a lever that closes the circuit when you pull the lever. KT and Bafang controllers are Normally Open.