Single Drive -vs- Dual Drive
- Thread starter onloop
- Start date
onloop
10 kW
- Joined
- Jun 24, 2013
- Messages
- 600
I've been reading alot about electric bikes lately...
there are very few people building electric bikes with dual motors... It seems that if they do have dual motors it is primarily to improve traction... for snow & sand.... and of course there are also some people who just can't get enough power... whether its needed or not.
So yes dual motors on a bike would give a lot more torque... but so would a larger motor... or a non hub motor that uses gearing like the Mid drive bbs02 from bafang.
Even the tesla car comes with only a single electric motor (in late 2014 tesla have release the P85D with dual motors - mainly so they can claim the fastest car on the road title, with 0 to 100km/hour in 3.2 - read more here )
I believe one of the main reasons for tesla doing this was to get all-wheel-drive which is all about traction... getting the power down without wheel spin greatly improves acceleration..
So why two motors on a skateboard, losing traction only really occurs on moist, polished concrete paths.. and that is really only when you are riding in a style that is prone to losing traction, say when slamming the throttle 100% on and drag racing cars....
PROS
> Dual motors double the torque of a single motor of the same size, it does not give you higher top speed as that is controlled by gearing ratio, wheel diameter, voltage & motor KV.... so why do we need more torque?... 1. if you want to go up long steep hills. 2. If your a big person weighing 95kg or more.
> To get more torque from a motor it needs to get bigger, the length & diameter increase, because there is a physical limit to the size of a single motor that can fit beneath a skateboard dual motors is the only option for people who want max torque.
> Claimed (more data needed) better handling / steering.... no torque steering.
> More traction when braking. Two wheels on the ground that have a brake force.
> offers a built in fail safe... if one motor fails when riding you could limp home on the other.
CONS
> More expensive
> Heavier
> More mechanical parts = may increase chance of failure
> More electrical parts = may increase chance of failure
> more complex to maintain.
> less efficient use of power? (honestly i can't be sure if this is 100% true, but many people who i respect & are much smarter then me say it is true & i believe them)
> may have more torque but it might not be unusable torque due to loss of traction, so when talking about useable torque dual motors might not be any better when compared to a single larger motor...
If a single motor can produce enough torque (or same as dual motors) for normal use I suppose this eventually leads to a discussion on topics such as
> single motor electric skateboards with differentials
> single motor skateboards (trucks) with live axle
> or single motor with two drive pulleys (one on each end of the motor shaft) driving two wheels. Two wheel drive without Diff.
WHY? because this would improve traction for brake force & improve traction for rapid acceleration.
there are very few people building electric bikes with dual motors... It seems that if they do have dual motors it is primarily to improve traction... for snow & sand.... and of course there are also some people who just can't get enough power... whether its needed or not.
So yes dual motors on a bike would give a lot more torque... but so would a larger motor... or a non hub motor that uses gearing like the Mid drive bbs02 from bafang.
Even the tesla car comes with only a single electric motor (in late 2014 tesla have release the P85D with dual motors - mainly so they can claim the fastest car on the road title, with 0 to 100km/hour in 3.2 - read more here )
I believe one of the main reasons for tesla doing this was to get all-wheel-drive which is all about traction... getting the power down without wheel spin greatly improves acceleration..
So why two motors on a skateboard, losing traction only really occurs on moist, polished concrete paths.. and that is really only when you are riding in a style that is prone to losing traction, say when slamming the throttle 100% on and drag racing cars....
PROS
> Dual motors double the torque of a single motor of the same size, it does not give you higher top speed as that is controlled by gearing ratio, wheel diameter, voltage & motor KV.... so why do we need more torque?... 1. if you want to go up long steep hills. 2. If your a big person weighing 95kg or more.
> To get more torque from a motor it needs to get bigger, the length & diameter increase, because there is a physical limit to the size of a single motor that can fit beneath a skateboard dual motors is the only option for people who want max torque.
> Claimed (more data needed) better handling / steering.... no torque steering.
> More traction when braking. Two wheels on the ground that have a brake force.
> offers a built in fail safe... if one motor fails when riding you could limp home on the other.
CONS
> More expensive
> Heavier
> More mechanical parts = may increase chance of failure
> More electrical parts = may increase chance of failure
> more complex to maintain.
> less efficient use of power? (honestly i can't be sure if this is 100% true, but many people who i respect & are much smarter then me say it is true & i believe them)
> may have more torque but it might not be unusable torque due to loss of traction, so when talking about useable torque dual motors might not be any better when compared to a single larger motor...
If a single motor can produce enough torque (or same as dual motors) for normal use I suppose this eventually leads to a discussion on topics such as
> single motor electric skateboards with differentials
> single motor skateboards (trucks) with live axle
> or single motor with two drive pulleys (one on each end of the motor shaft) driving two wheels. Two wheel drive without Diff.
WHY? because this would improve traction for brake force & improve traction for rapid acceleration.
torqueboards
1 MW
Single Drive is perfect for flats.
I prefer Dual Drive for uphill riding. I suggest if your commuting and/or riding frequently uphill and downhill. I highly recommend a dual motor setup.
If your route is 50-60% uphill/downhill riding. I would prefer a dual motor setup.
If you aren't a single motor is more then enough for flat grounds.
Granted dual motor will cost more money in the long run but you will actually save money depending how crucial and rugged your uphill/downhill riding is.
Why I prefer dual motor? PROS
- Dual motor will provide more power with the same battery pack which will otherwise be wasted and not used since most 50mm motors are capped at 60amps and 63mm motors are capped at 80amps.
- Dual motor provides less stress on one motor when going uphill and downhill.
- Dual motor provides twice as much torque as a single motor.
- Dual motor is more fun!
I prefer Dual Drive for uphill riding. I suggest if your commuting and/or riding frequently uphill and downhill. I highly recommend a dual motor setup.
If your route is 50-60% uphill/downhill riding. I would prefer a dual motor setup.
If you aren't a single motor is more then enough for flat grounds.
Granted dual motor will cost more money in the long run but you will actually save money depending how crucial and rugged your uphill/downhill riding is.
Why I prefer dual motor? PROS
- Dual motor will provide more power with the same battery pack which will otherwise be wasted and not used since most 50mm motors are capped at 60amps and 63mm motors are capped at 80amps.
- Dual motor provides less stress on one motor when going uphill and downhill.
- Dual motor provides twice as much torque as a single motor.
- Dual motor is more fun!
onloop
10 kW
- Joined
- Jun 24, 2013
- Messages
- 600
How many people have a single motor board with a big motor? I'm talking 6374? Running high voltage like 10s? Weight over 90kg? Ride up decent sized Hills?....
I think Vedder has this. But who else?...
Everyone always wants a cheaper setup and everyone always crazy fast top speed and go up cliffs... Single motors could be the best way to do it.
I think Vedder has this. But who else?...
Everyone always wants a cheaper setup and everyone always crazy fast top speed and go up cliffs... Single motors could be the best way to do it.
torqueboards
1 MW
onloop said:
Sure, I agree. It's great but you already have all the components. Why not add a second motor for $150-250 - ESC, Motor, Drive Train for double the power.
10S x 3.7v = 37V x 80Amp = 2960 watts x 2 motors = 5920 watts *granted as long as you can pull 160+ amps from your pack. 20C lipos and/or 5000mah packs won't cut it. Need at least 10ah 20c for 200amps or 5ah 40c.
Sure if no hills.. single motor is all you need. Dual motor is a complete waste in that sense.
20-30 degree hills with single motor. I don't think it would last long and/or would severely shorten the lifespan of all the components. If so, use 15mm width belts.
It's not bad though. I do like both setups
Single motor on 10S is still a beast but Dual motor on 10S is more of a beast. I just like two motors. It's also what separates a DIY versus a Production board IMO besides boosted. But boosted is also severely limited in power/speed compared to DIY boards.What does everyone else think? I know Beto likes single motor on 12S. Might be because there are no hills in his area.
whitepony
10 kW
- Joined
- Feb 19, 2015
- Messages
- 663
the only thing i dont like about a single engine setup is, that the wider your trucks are, the stronger the steering impulses will be when you accelerate/brake. this is very pronounced on my evolve carbon all terrain setup (with the street setup it feels okish).
what i wouldnt like about a double engine setup is the engine brake - for example you can hardly push a boosted dual+ whereas my evolve carbon with street setup barely needs the engine when it goes slightly downhill.
what i wouldnt like about a double engine setup is the engine brake - for example you can hardly push a boosted dual+ whereas my evolve carbon with street setup barely needs the engine when it goes slightly downhill.
torqueboards
1 MW
whitepony said:
That's where the hub motors come in - less drag.
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