Two motors to one battery

Noobie

10 µW
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Jul 10, 2015
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I'm wanting to connect two Q100 motors to one Panasonic 10Ah battery. Haven't seen a schematic, do I just join the power wires and the phase wires of each motor before going to the battery? I plan to use separate identical KU63 controllers and plan to use two throttles but would rather use one throttle if it is safe. All bms stuff. Thanks
 
A Panasonic 10Ah bttery won't be able to provide enough current for both motors at once. In principle, you just connect both controllers to the same battery. You can try one throttle to both controllers. There's a fair chance it'll work OK. You connect it to one controller, then take a branch of the signal wire and only connect that to the second controller, leaving the ground and 5v wires (black and red) empty.
 
How about both motors at half or 2/3 power each until I get more battery. What happens with both on full?
 
Noobie said:
How about both motors at half or 2/3 power each until I get more battery. What happens with both on full?

1/2 power should be fine. Full power the battery BMS over current protection will probably trip. And if it doesn’t you’ll likely send the cells to an early grave. Give it a try and let us know what happens.
 
You would only join the power wires from both controllers to the battery wires. Don't join the phase wires.

As said, that little battery is only capable of putting out enough power for 1 motor. You could run 2 motors at 1/2 power. However, you have some losses in each controller so 2 motors being run at 1/2 would be slightly less powerful and efficient than 1 motor at full power.

If you want to run 2 motors, you need a bigger, more powerful battery.

Here's a basic diagram.

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To nit pick, it would be ok if you only used one motor at a time, with the dual throttles.

But yeah, you really need a bigger battery, or two batteries to run two motors. Or deep pockets to buy your next battery soon.
 
How about a 20Ah 36 v battery, two Ku63 controllers and one throttle to run two Q100 motors? How do people find out about this stuff?
 
This one can do it. It's cheap, light and reliable.

https://bmsbattery.com/ebike-battery/445-36v-20ah-li-ion-shrink-tube-ebike-battery-pack-battery.html
 
Most 20 ah lithium batteries out there could run a 30 amps controller, or two 15 amps controller.

But most of us totally fail to see why you'd do that, since one only slightly larger motor works good on 30 amps.

Two 30 amps motors, now yer talking! That will haul a trailer up a hill.
 
Noobie said:
How do people find out about this stuff?

Experience, Research, Engineering backgrounds, and Asking a ton of questions on the forum.

The bigger battery should work, as long as it's amp output is at least twice the amp rating of either controller. Which brings up a point. Your battery's rated amp output must always be equal to or higher than the max output of the controller.

A two motor system can work, and sure sounds cool. If you want to build it just for the fun factor, go for it. But It has very limited use and in almost all cases simply using 1 larger motor and 1 wheel drive performs much better than 2 motors and 2 wheel drive. That might sound counter intuitive, but a bicycle is very rarely in a situation where it can't get enough traction to move. In those situations, having the front tire start top slip is a total disaster. Once the front tire loses traction, you lose all ability to balance the bike and will be on the ground at 9.81 m/s2

Unlike a car where all wheel drive is good and you sometimes need it to keep traction, on a bike, if you don't have enough traction from the rear wheel, you just upgrade the tire. If you encounter something where traction is impossible, like a Slip-n-Slide covered in dish soap and bovine birthing lube, try going around it. :mrgreen:
 
I don't think he'll lose traction with a Q100. Might be different with a pair of Cromotors. I have a bike with two Q100s and the traction is incredible. You can ride on the slipperiest surfaces like mud snow and wet grass on inclines at any angle that would be impossible on a single motored bike. That's about the only use for 2WD, otherwise a single motor is better, except for maybe dual suspension bikes where small motors allow the suspension to work better.
 
Two small motors will definitely make a good climber, better than jacking up the power on one.

Go for it if your controllers will be weak enough, 10-12 amps, and you have the motors in hand. If you need to go buy stuff, just get a bigger motor, and run it on 20-25 amps controller with that battery.
 
I am a big fan of using a CA V3 and a remote shunt when building 2WD bikes.

The remote shunt allows both controllers to share one battery connection. The remote shunt is the connection nearest to the battery on the mains, so all the battery current from both systems runs through the remote shunt.

The CA V3 connects to the remote shunt, and a single throttle connects to the CA.

The Throttle output (Signal wire only) from the CA can be parallel connected to both controllers.

With this set-up, the CA modulates the throttle to both controllers to maintain/limit the system current/power.

I cover the process a little more detailed in this thread:

http://endless-sphere.com/forums/viewtopic.php?f=6&t=70299#p1065619
 
Good plan.
 
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