1 controller for 2 (or more) motors

[bluesrocks]

I'd like to be able to use 2 or more motors at the same time and I'm on a shoe string budget. Granting the motors are all the same size and model, and as long as I plan the system ahead of time, could I use one amp controller (and battery pack) to cause all the motors to run together at the same time?

So far I thinking of putting lightweight brushless motors at each wheel improving traction from multiple drive wheels and it all needs to work well from one throttle controller system. Can I do that and if so, should I attach them in series or parallel to keep the current in the right range?

Helpful suggestions welcome!

 

[vanilla ice]

Theres no easy way to do this with brushless motors. You need to use two controllers. You can use one throttle and one battery for both controllers. The controllers are cheap enough relative to the bat that it doesn't really matter from a cost perspective.

 

[PhoenixOSU]

Not if it is a brushless motor. I don't really recommend you do this even with a brushed motor, laod balancing could be serious issue here, it would be hard to turn, and it would be hard to keep the two running the same speed.

If you use an induction motor it MIGHT work OK. If you use a brushless motor, well it just flat out wont work because the controller needs to know the position of the motor (either with back emf sensing or hall sensors) in order to determine how to drive it, and if there are 2 motors then the rotors will not always be lined up, and so how do you drive two motors differently from one connection point? you don't! A brushed motor doesn't need feedback per sey, so those might work. But again, there is no way to easily control how much power each motor gets and one may spin slightly better than the other.

In general if you do the research, you will find that it is cheaper to use a single motor anyway.

I don't suggest going dual motors unless you really know what your doing, and given the nature of the question, I'd seriously recommend for safety reasons that you stick with one motor.

 

[Malcolm]

Is this for a bike or car?

For a car, with brushed motors, you might find this interesting: http://www.4qd.co.uk/faq/bmnc2.html#diff

 

[dumbass]

I'd like to be able to use 2 or more motors at the same time and I'm on a shoe string budget. Granting the motors are all the same size and model, and as long as I plan the system ahead of time, could I use one amp controller (and battery pack) to cause all the motors to run together at the same time?

So far I thinking of putting lightweight brushless motors at each wheel improving traction from multiple drive wheels and it all needs to work well from one throttle controller system. Can I do that and if so, should I attach them in series or parallel to keep the current in the right range?

Helpful suggestions welcome!

I don't see why it can't be done. After all Cyclone sells a twin motor setup and they use one controler, one battery and one throttle. Take a look at it at their site http://www.cyclone-tw.com/order.htm

 

[archer-ca]

I'd like to be able to use 2 or more motors at the same time and I'm on a shoe string budget. Granting the motors are all the same size and model, and as long as I plan the system ahead of time, could I use one amp controller (and battery pack) to cause all the motors to run together at the same time?

So far I thinking of putting lightweight brushless motors at each wheel improving traction from multiple drive wheels and it all needs to work well from one throttle controller system. Can I do that and if so, should I attach them in series or parallel to keep the current in the right range?

Helpful suggestions welcome!

I don't see why it can't be done. After all Cyclone sells a twin motor setup and they use one controler, one battery and one throttle. Take a look at it at their site http://www.cyclone-tw.com/order.htm

Actually if you go to their site http://www.cyclone-tw.com/dc24.htm you can scroll half way down to see the picture of the Dual 1000watt kit and there are two controllers. If I was nutz enuff I woulda picked that one instead of the 1200watt kit I have coming...

Cheers,

Norman

 

[wasp]

crystalite sells a dual motor brushless controller 325 canadian
i'll look for the site and post
itsellectric.ca

 

[bluesrocks]

Thanks everyone, I appreciate all the tips and suggestions. At first I'm probably going to be stuck just converting a bicycle to electric assist, but I'd prefer stripping down (all terrain bicycle tires instead of huge heavy ATV tires), stretching (from 1 to 2 seats) and converting a used quad ATV into a lightweight enclosed (fairing and fabric jacket) electric (optional pedal power) vehicle. I could be swayed into using a simple custom frame, something like sand rail meets velomobile.

I'd like to include a high torque gear reduction setting for lower top end speed (35mph) but greater acceleration for some off road fun. I'd also like some serious range, so I'm thinking maybe
08-7.5ah 12v AGM or maybe
12-5ah 6volt. If I get say four brushless RC aircraft motors, one for each 20" tire, then I get 4 wheel drive with almost no drivetrain other than electric wires! Should work well with 2 wheel drive. I can't shake the need to go tear it up like a mini dune buggy, but it has to be road legal (moped, power assisted bike, slow moving vehicle, etc).

hmmmm?
It would be nice if they had some sort of limited slip arrangement so that no single tire would spin freely while the others dig in. A computer chip should sense the rpm imbalance and respond by slowing down the runaway tire(s) while simultaneously diverting power to the slower wheels where it's needed. Is there a way to do that?

 

[Rassy]

Hi bluesrocks. I have run three brushed motors from one throttle and one battery pack, but with three separate controllers. This was done on both a mountain bike and on a delta recumbent trike, with one motor on the front wheel and the other two motors on a two wheel pusher trailer. It worked great. Some folks usually chime in about controlling slippage and cornering problems, but the nature of electric motors is such that they are always trying to reach a higher rpm then the load permits (at any throttle setting), so if any motor takes more than it's share of the load the other motors try to pick up more speed, and they all just balance out. If one wheel has to travel a different distance during cornering the same principal applies, since there is no physical connection forcing the wheels to rotate the same. Of course for best results the motors, controllers, and wheels should all be the same.

One other comment, most states treat two and three wheel vehicles different than they treat four wheel vehicles, so there may be some legal issues for on road use.

 

[dumbass]

I'd like to be able to use 2 or more motors at the same time and I'm on a shoe string budget. Granting the motors are all the same size and model, and as long as I plan the system ahead of time, could I use one amp controller (and battery pack) to cause all the motors to run together at the same time?

So far I thinking of putting lightweight brushless motors at each wheel improving traction from multiple drive wheels and it all needs to work well from one throttle controller system. Can I do that and if so, should I attach them in series or parallel to keep the current in the right range?

Helpful suggestions welcome!

I don't see why it can't be done. After all Cyclone sells a twin motor setup and they use one controler, one battery and one throttle. Take a look at it at their site http://www.cyclone-tw.com/order.htm

Actually if you go to their site http://www.cyclone-tw.com/dc24.htm you can scroll half way down to see the picture of the Dual 1000watt kit and there are two controllers. If I was nutz enuff I woulda picked that one instead of the 1200watt kit I have coming...

Cheers,

Norman

I stand corrected. They are using 2 controlers but just one throttle. As for choosing that setup....no I wouldn't choose it. But it was to ilistrate that it can be done.

 

[vanilla ice]

I'm not sure what kind of usage you had in mind, but those few SLA's may not be up to the job of pulling around a quad RC motor ATV framed tandem thingamabob. An ATV based frame is going to be heavy, then you're adding a lead pack to that. And the pack is going to need to be 2 or 4 times what you stated imo. The above pack is certainly not going to offer enough capacity to rip it up in the dunes for more than a few minutes..

On road cruising around use is going to be a lot easier on power consumption, but then like was said- you would run into legality problems having four wheels. At least in my area you would.

 

[bluesrocks]

Not so good for the road
Ok, so if I'd stick with a quad on and off road project, then how about starting out the four wheel bike (pedal power only) registered as a bike. Then legally upgrade to electric power assisted bike. ... Yes no...

Or is the doubt around street legal because of too many powered wheels, arguing it's over powered?

Quad approach is too heavy
If I stick with modding a quad atv frame, I mostly just need the suspension and turning mechanisms. That plus helpful parts of the frame is all I need from it. I think that it's perfect that they are relatively substantial (heavy duty) for use in such a lightweight vehicle. I'm not looking to create the lightest and most efficient commuter. I'm specifically wanting some off road fun included in the package. Having stout turning and suspension components seems like a great idea, lending well toward reliable and safe long term use.

However, if there are better arrangements then I'd like to hear about such things as I have even considered unusual things like all wheel steering, say 30/70 rear/front in order to improve hard cornering and reduce front wheel well depth. By tilting the forks back like most bikes and motorcycles do, you simultaneously tilt the tire as you turn. The wider you turn, the deeper it tilts the wheel. So I could be persuaded toward some sort of custom design for maximum weight savings, but then I'd need ideas for suspension.

If I would convert a quad, the stripping and stretching would cut the weight down significantly. I might stick with a single seater with large size trunk capacity. And of course, if I need more batteries or greater amp hours, then that is what I'd need to do. Suggestions for (AGM) battery bank (how many ah's at so many volts) and matched motors (voltage range and amp ratings) and controllers and throttle?

 

[bluesrocks]

Is this for a bike or car?

For a car, with brushed motors, you might find this interesting: http://www.4qd.co.uk/faq/bmnc2.html#diff

Differential gearing

When using two motors on opposite sides of a vehicle, some people ask whether one or two controllers are required.

If you are using the motors for steering purposes, then you have to drive them at different speeds to get the steering action and then true differential drive, using two controllers, is indeed required.

But if you have mechanical steering, and the motors are drive only (and do not steer), then in practise you only need one controller. It is common practise for ride-on golf buggies (which can have quite a small turning circle) to simply drive two motors in parallel from one controller. This causes no problem in practise and the differential action is adequate.

Thanks Malcom, interesting read!

I probably don't understand something correctly, but some say don't use two or more motors with one controller, it wouldn't work, or it wouldn't work well. Yet the reference above says it shouldn't be a problem, after all it works well in golf carts all the time.

The comment about differential action seems rather encouraging that multiple motors working from one controller need not cause steering/handling/speed mismatch problems, but instead seem markedly adaptable concerning changing load (rpm and torque) requirements, perhaps functionality similar to a limited slip differential. 8)

Any suggestions for a custom built frame on a string budget? My friend has a muffler tube bender, so perhaps we could put something together at his shop. But I need a solid design and a way to provide shock absorption.

 

[Malcolm]

You originally asked about brushless motors, which have to be powered by individual controllers unless you're an electronics wizard. The qed site refers only to brushed motors, which are much simpler to control.

I'm also interested in using a pair of motors with a single controller, in my case to power the front wheels of a classic Mini, with each wheel being driven independently by a toothed belt. From what I've read, this should work well with both motors wired in series, but I'd also like to try it in parallel to take advantage of the full voltage range of the controller. According to the qed site the motors should act rather like a limited slip diff when wired in parallel, so there could be tire scrub on tight turns. But since I'm unlikely to be making very tight turns at speed this should not be a problem. One thing you do have to guard against in an arrangement like this is the possibility of one belt breaking, in which case the freed motor could over-rev to destruction.

For a self-build I think this would make a good starting point: http://www.crank-it.com/quadfeatures.html

 

[liveforphysics]

If you mean brushless hub motors, than like these other guys said, you definatly need 1 controller per motor.


If you mean brushless motors that are mechanically linked and drive the rear axel, then you can absolutely run 1 controller for 2 motors. Make sure they are clocked and locked mechanically in time with each other, then wire them in series, and take the hall signal from one of the motors to feed the controller. However, you need double the voltage to get the same performance with this method.


I'm unclear on your reason for wanting to power more than 1 axel or set of wheels? Just power the rear is more than adquate for even the most potent of electrical setups ever implimented. I've played on a +100hp banshee quad on pavement running the absolute WRONG tires(dirt knobbys) on pavement, and still it would effortlessly lift the front wheels towards the sky prior to having any traction issues.

The concept of AWD for a commuter type vehicle is an exercise in lowering efficiency and adding weight and complexity to something that simply doesn't require it.

Or maybe I'm unclear on what the project goals are?

 

[bluesrocks]

If you mean brushless hub motors, than like these other guys said, you definatly need 1 controller per motor.

If you mean brushless motors that are mechanically linked and drive the rear axel, then you can absolutely run 1 controller for 2 motors. Make sure they are clocked and locked mechanically in time with each other, then wire them in series, and take the hall signal from one of the motors to feed the controller. However, you need double the voltage to get the same performance with this method.


I'm unclear on your reason for wanting to power more than 1 axel or set of wheels? Just power the rear is more than adquate for even the most potent of electrical setups ever implimented. I've played on a +100hp banshee quad on pavement running the absolute WRONG tires(dirt knobbys) on pavement, and still it would effortlessly lift the front wheels towards the sky prior to having any traction issues.

The concept of AWD for a commuter type vehicle is an exercise in lowering efficiency and adding weight and complexity to something that simply doesn't require it.

Or maybe I'm unclear on what the project goals are?

I appreciate the helpful responses, and I stand corrected about several brushless motors in-that apparently unless they are mechanically in sync, they need a separate controller for each motor.

I have an unshakable desire to not only commute to the local store/watering hole, but to also go off roading with the same vehicle. It's my version of a green personal sized SUV. I'm willing to create a lightweight purpose built frame as long as the handling components (steering geometry and suspension) can handle some a long term habit of occasional off roading. It should be narrow enough for most bike trails (single seat width) and yet be somewhat roomy with decent hauling capacity. If I'm going overkill (too heavy) with a quad ATV conversion idea, then what's a good alternative for long term off road steering and suspension geometry and mechanism?

The main attraction to a motor at every wheel has to do with eliminating the heavy and cumbersome traditional 4wheel drive train. Therefore for those (like me) who would like 3-4wheel drive without the entire (traditional) drivetrain, then the idea to just replace it with a (reduction geared) motor at every wheel seems like a great solution.

Any scavenge/surplus suggestions to help me find some fairly efficient motors/controllers? Thanks.

 

[vanilla ice]

Take a look at doc's and raider's pics from their meet up. That is more what you should be doing if you want to build a bicycle or motorcycle off-roader/commuter. You can ride two up with a long enough seat. Why are you wanting more than two wheels?

 

[bluesrocks]

Thanks vanilla ice, I will check it out right away.
4 vs 2 wheels is mostly for safety and health reasons, plus the inherent additional space utility from a personal transportation vehicle. I have chronic back pain so I'm attracted to recumbent style riding position, but I simply can't afford a typical recumbent bike/trike. That plus one of the main drivers for this 3-4 wheel vehicle, hopefully 4 wheel, would be my gf, and to be blunt, she's simply not the most athletic inclined. So from my perspective, and especially as long as sticking with a smaller footprint design, a lightweight 4 wheeler provides the best format to provide long term stability and safety, while at the same time remains sporty enough for some serious off road fun.

I could be swayed toward a trike or bike, but I'd much prefer a bike conversion after creating the main vehicle we need, commuter transport. We may want to be able to make 30-40mile round trips. So I'm prepared for a rather heavy battery bank which lends well toward a slightly larger and safer 4 wheel vehicle. Safer because all the heavy additions (batteries and motors) are placed at the lowest locations providing an extremely low center of gravity. This virtually eliminates a very high center of gravity that is common for a long range bike running on heavy SLA's.

BTW, what's the latest for new improved battery technology? Perhaps things like super capacitors mixed in with traditional batteries, or alternative battery designs like super magnetism or perhaps some new improved nano-tube process, etc? Also, another way for me to reduce this conversion cost would be to reclaim a motor that we already have, like from an electric leaf blower for example. Or what sort of common electric motors should I look for (washer/dryer, vacuum, drill)? Concerning common AC appliances like washer/dryer for example, do the motors themselves run on AC, or do some of them get converted to (and run on) DC? Since I'm starting with DC power from sla betteries, I'd assume it's more efficient to stick with a dc motor instead of inverting to AC because that would require including the energy losses involved in the conversion process.

My friend has a tube bender for exhaust systems that "might" prove useful. I wish bamboo was native to my area, lighter and stronger than steel.
:wink:

 

[bluesrocks]

...

For a self-build I think this would make a good starting point: http://www.crank-it.com/quadfeatures.html

Malcom
Gotta give credit for this excellent find. I haven't seen that website in a long time. This design is very close to what I'm after!

Check out this website for more info on this mountain quad. http://www.crank-it.com/quadfeatures.html#lightweight

At 58lbs base model, this lightweight design would be great. This unit sold (not sold anymore) for around 7 grand! hehehe Probably why it's not sold anymore. Suggestions for how to custom build simple and effective steering and suspension parts? I'm guessing that I could get a used quad ATV without engine for $150, so lets limit $200 for a custom built frame. Perhaps use some sort of elastomer suspension.

 

[bluesrocks]

Check out the following link for an interesting pamphlet of rules for a lightweight electric vehicle competition. They all use a max of 67 lbs of SLA batteries, aside from staying within their guidelines, the rest is pretty much up to you! Half way into it they do a slick job covering some do's and don'ts concerning things like suspension and steering, some of which may prove helpful.
8)
http://www.electrathonamerica.org/

I downloaded the race rules for a lot of cool examples of fast electric 3 & 4 wheelers. Nicely done publication. Some sweet looking rides. And, it has a robust resource list including many links for things like parts and kits for electric vehicles. Here's a shot from the gallery.

I'm inspired toward creating my own frame. But I'm not a welder, and we are on a shoe string budget. :? I really hope I can get something going soon...

 

[vanilla ice]

Love to be proven wrong, truly.. but I get the feeling something has got to give; low budget, beginner builder, quad, off-road, tandem, velo, sla, long range. It doesn't add up. IMO best go with a road bent trike or off-road two wheeler to start things off.

 

[bluesrocks]

It's true that finances may dictate that I may need to convert a bike first. Didn't I already say that... :lol:

It's my view that the glass is half full and the quad project is worthy of pursuit. I don't like trikes, prone to tipping while cornering and too small in terms of interior hauling space. I'd also like it (mostly) enclosed. So a quad is what I'm after right now.

I'll go back and reread this thread to refine what kind of help I'm looking for.

 

[bluesrocks]

Hi bluesrocks. I have run three brushed motors from one throttle and one battery pack, but with three separate controllers. This was done on both a mountain bike and on a delta recumbent trike, with one motor on the front wheel and the other two motors on a two wheel pusher trailer. It worked great. Some folks usually chime in about controlling slippage and cornering problems, but the nature of electric motors is such that they are always trying to reach a higher rpm then the load permits (at any throttle setting), so if any motor takes more than it's share of the load the other motors try to pick up more speed, and they all just balance out. If one wheel has to travel a different distance during cornering the same principal applies, since there is no physical connection forcing the wheels to rotate the same. Of course for best results the motors, controllers, and wheels should all be the same.

One other comment, most states treat two and three wheel vehicles different than they treat four wheel vehicles, so there may be some legal issues for on road use.

Thanks for clarifying how electric motors have variable torque/speed trade off's such that they basically track in turns well perhaps similar to a semi-slip rear end differential in a car. Sounds like a cool trike rig. It should be appreciably safer in a 4 wheeler than on 2, plus safer and more stable than 3 wheelers.

This 4 wheel electrified bike project could really help us. If we end up 1)saving on transportation costs, 2)help the environment, 3)exercise more, and 4)truly enjoy the ride, then that would be huge for us!


Do different places in USA not allow pedal cars like the Rhoades car for example?


Maybe I'm wrong, but I figure if it starts out registered as a 4 wheel pedal vehicle (no power assist), they should accept the latter electric assist upgrade as a "power assist bike".
Or is that wishful but unrealistic thinking? :?

 

[bluesrocks]

Wow, I am sorry I lost this thread. I didn't realize I had been gone for so long.

I will respond soon, and thanks much to all your input, interesting stuff!

Blues

 

[dumbass]

Hi bluesrocks.

Do different places in USA not allow pedal cars like the Rhoades car for example?


Maybe I'm wrong, but I figure if it starts out registered as a 4 wheel pedal vehicle (no power assist), they should accept the latter electric assist upgrade as a "power assist bike".
Or is that wishful but unrealistic thinking? :?

While bicycles are excepted in the US on all but high speed roads (express and toll roads) I don't think 4 wheels peddle bikes are. IF you read the fed and Illinois (my state) I beleive it indicates the rules for electric bike to include 2 and 3 wheel only and in no way includes a 4 wheel bike. Therefore, it would not be legal on ether the roadways and certainly not on bike trails. Not to mention the width would creat a problem on most if not all trails. These are some of the reasons why I have been looking into tandem tricks only.

Bob