Running 2 motors from one controller?

[job]

Hi all,

I am thinking of installing a dual motor setup, one on the front and one on the rear,

Battery: 36v 11ah
Motor #1 : 350w 36v gearless
Motor #2 : 300w 36v geared
Controller : 36v (10a?)

I'm not sure how to accomplish this so I've come up with a few possibilies, perhaps the gurus here can advise me..


Method 1 => Definite way, run both setups independently, two controllers, two batteries, two throttles, but going to take up the most space (esp battery) and will be ackward with 2 throttles.. but can be independently powered
Method 2 => One battery, two controllers, each motor wired to each controller (still take up space and two throttles, but less the battery)
Method 3 => One battery, one controller, 2 motors wired in parallel? (Not sure if this can work as the geared motor will have a lower max rpm..)

What would be the best way? Any pros and cons of the setups?

Cheers!

 

[amberwolf]

Re: Running 2 motors from one controller?

Only possible with brushed motors/controllers, or if the rotors of brushless motors are physically locked together. There is a recent (last couple weeks or so) thread in skateboard/scooter section about this.

Method 1 => Definite way, run both setups independently, two controllers, two batteries, two throttles, but going to take up the most space (esp battery) and will be ackward with 2 throttles.. but can be independently powered
Method 2 => One battery, two controllers, each motor wired to each controller (still take up space and two throttles, but less the battery)

These two are possible, been done a lot, search for threads with 2WD or AWD or "dual motor" or "two motor*" (etc) in the titles for plenty of info, experiences, and good/bad/etc. .

https://endless-sphere.com/forums/search.php?keywords=2WD&terms=all&author=&sc=1&sf=titleonly&sk=t&sd=d&sr=topics&st=0&ch=300&t=0&submit=Search

https://endless-sphere.com/forums/search.php?keywords=AWD&terms=all&author=&sc=1&sf=titleonly&sk=t&sd=d&sr=topics&st=0&ch=300&t=0&submit=Search

https://endless-sphere.com/forums/search.php?keywords=dual+motor&terms=all&author=&sc=1&sf=titleonly&sk=t&sd=d&sr=topics&st=0&ch=300&t=0&submit=Search

https://endless-sphere.com/forums/search.php?keywords=two+motor*&terms=all&author=&sc=1&sf=titleonly&sk=t&sd=d&sr=topics&st=0&ch=300&t=0&submit=Search

 

[job]

Hi Amberwolf.

Thanks so much for providing the links! So this is called a 2WD setup.. based on what i've read i'll probably go with twin controllers and twin throttles (so they can be controlled independently)

Will do more reserch..

 

[Alan B]

2WD or AWD, has been done a lot, most common is one battery, two controllers and one throttle or two throttles or one throttle with two hall sensors installed inside.

If you use controllers that have torque throttles things work more easily.

If you use the common speed throttles it is difficult to get both motors at the same speed when they are not identical. When one motor runs faster it will take the load and power, the slower motor will apply near zero power and torque.

Torque throttles automatically compensate for speed differences and balance the torque and can easily use one throttle.

You can read more about one example setup in the Bonanza thread linked in my signature below.

Incidentally, doubling the torque really makes an amazing ebike, but the extra weight, wiring and so on make it heavy and cumbersome to change flats on. There are a number of tradeoffs.

 

[motomech]

I have tried various throttle set-ups and far and away, I like this one best.
My independent throttles are together on the left side;


Half-twist next to a thumb, very natural to use.
But most of the time, I use PAS for the rear and add w/the thumb(frt. motor).
Ebrake only on the rear motor since the frt. is throttle only..

Before you get too far into this, you need to ask yourself what your goals are, why do you want 2WD?
Another question, why are you intending to run 36V systems?
In general, 48V systems provide better performance w/ little extra cost, both in $$$ and installation.
I have found the running matched motors(in terms of motor speed range) in a 2WD system works out best. I use geared motors exclusively, so have no experience w/ combining a DD and geared. What do you hope to accomplish combini9ng two different types of motors?
Two batteries don't necessarily have to be difficult to mount if a proper donor bike is used.
This is the first bike linked in my sig;

 

[job]

Hi all, thanks for your replies!

Ok because i currently have these hardware with me, it was from a donor unit so i have duplicates of both, my understanding is that geared motors have lower top speed then a gearless motor, but as a benefit it has much higher torque since the motor spins many times per wheel rotation

My aim was to combine the best of both worlds and perhaps use either motors for different situations or both combined for more power

After reading, I would most probably go with 1 battery, 2 controller and 2 throttle setup as it would help me achieve the above(s), besides my current front wheel does not have any brakes of any sort so the additional brake would be useful as well

Would the battery get stressed out from 2 motors drawing from it at full load?

 

[Alan B]

Nice dual throttle setup Motomech!

Battery stress is a real issue. The battery and BMS must be able to handle the current for both controllers. On the Bonanza I use a 50/70 amp BMS and battery, but I limit the draw to 45A by programming the controllers. You need a strong battery.

You can also use 2 batteries, and if you are using one throttle tie the grounds together at the controller. Separate throttles allow the two systems to be independent.

If you are using 2 throttles the motors don't need to match. I'm using a DD and a gearmotor that have similar top speeds and they work fine together. You will learn to throttle them in balance.

The DD is nice for reliable longevity. Just not much to go wrong there. The gearmotor is good for adding climbing and acceleration torque. One suggestion is to drop out the gearmotor once up to speed. Use only the DD at full cruise, and program the controller to shut off the gearmotor a bit below cruise speed.

 

[rojitor]

I had a 2wd setup time ago. Two batteries, two controllers, one half twist throttle and a thumb throttle. Worked like a charm.
Take a look at this thread https://endless-sphere.com/forums/viewtopic.php?f=2&t=33429

 

[dogman dan]

The setup I always wanted to try was a rear DD motor, and a front geared. DD on a throttle, but the geared would be on a push button. You'd get wide open throttle when you jab the button. 90% of the time you'd run the DD, but when you wanted that extra wattage for a hill, you'd jab the button as needed.

For a cargo bike, off road give me all the power on the rear wheel please.

 

[Alan B]

That's an interesting idea Dan. I have rear DD and front geared hubmotors, and PhaseRunner sinewave controllers with torque throttles. One throttle feeds both. It works well, but I plan to put a switch or switches to enable front / rear / both or something like that. A pushbutton to enable the front would work well since the torque throttle controllers balance the torque. If I put full throttle to the front motor it might get squirrelly but if the controller was setup for moderate full power it might be fine. This could be combined with controller or display max speed setting dropping the front motor at a bit below level cruise speed, on a hill it would stay in, on the level it would drop out as cruise was reached.

Dual motors really help when accelerating and when climbing. A geared motor drops out completely when power is removed due to the clutch. The DD motor just doesn't wear out, whereas the geared motor will wear out clutches and gears, so combining them in this way (with only brief part time use of the gearmotor) will make for a very low maintenance setup over the long term. Plus if the gearmotor does have a failure you'll still have a motor to help you get home. Plus regen on the rear DD is great for saving on the brake pads, making them last nearly forever.

 

[motomech]

The setup I always wanted to try was a rear DD motor, and a front geared. DD on a throttle, but the geared would be on a push button. You'd get wide open throttle when you jab the button. 90% of the time you'd run the DD, but when you wanted that extra wattage for a hill, you'd jab the button as needed.

For a cargo bike, off road give me all the power on the rear wheel please.

The way I have my thumb throttle on the frt. motor is more more less like a push button. Often, I just jab it.
Seldom would I have the frt. motor "on" long enough that my thumb gets tired, and I retain the ability to "feed" the power in iffy traction situations. I really don't think there would be any advantage to a button.
Now if a guy could rig a set-up that when the rear throttle was twisted wide open, it would activate the frt., that would be kinda cool. Safe enough for the street w/ a low-powered frt motor like I have.

 

[motomech]

That's an interesting idea Dan. I have rear DD and front geared hubmotors, and PhaseRunner sinewave controllers with torque throttles. One throttle feeds both. It works well, but I plan to put a switch or switches to enable front / rear / both or something like that. A pushbutton to enable the front would work well since the torque throttle controllers balance the torque. If I put full throttle to the front motor it might get squirrelly but if the controller was setup for moderate full power it might be fine. This could be combined with controller or display max speed setting dropping the front motor at a bit below level cruise speed, on a hill it would stay in, on the level it would drop out as cruise was reached.

Dual motors really help when accelerating and when climbing. A geared motor drops out completely when power is removed due to the clutch. The DD motor just doesn't wear out, whereas the geared motor will wear out clutches and gears, so combining them in this way (with only brief part time use of the gearmotor) will make for a very low maintenance setup over the long term. Plus if the gearmotor does have a failure you'll still have a motor to help you get home. Plus regen on the rear DD is great for saving on the brake pads, making them last nearly forever.

I'm really confused about the effectiveness of regen's ability as a braking system.
It would seem to me that the comments here are split about 50/50. Some say it's not worth the trouble, while others tout it's virtues.
Anyone want to comment on if there is a simple reality, or do to many factors come into play that there is no "set" answer.

 

[motomech]

I've mentioned this before, but I think it is worth repeating.

After years of using 2WD, I have come to believe that the single biggest benefit is being able the run higher overall power levels w/out needing any type of throttle conditioning or torque management. It's a boon to us "low-tech" guys and the thing that I appreciate every ride, every day.
In my case, I'm running the recommended 25 Amp controller on my Ezee V1(12S LiPoly-46 V), or a system of around 1100 Watts. The throttle is smooth and overall, the the system is does what it needs to do, getting me up to 24 MPH and climbing any hill w/out getting overly warm. But it's a little leisurely off the line w/ less-than-thrilling acceleration.
But add the 900 Watts from the Q100H and the thing fairly well scoots, being able to "jump" unsuspecting cars off the line. And, although both motors have the same motor speed range (260 RPM @ 36V), using both together can boost the top speed by 2 to 3 MPH.
Now if I took that 2000 Watts and put them on, say a single MAC, that would be faster still. A single motor on the same power as a dual system will accelerate faster, but I'm not sure how sensitive the throttle would be, or how a simple 3-speed PAS would interface w/ the rider.
I have never had a system failure that I couldn't rectify by the side of the road, so redundancy really hasn't been a factor.
The biggest down-side is weight.
Off-road, the benefits are obvious, traction.
The biggest down-side is the weight of the frt. motor. W/ my mini, most of the time it isn't noticed much, but lofting the frt. whl. to clear obstacles just isn't going to happen.

 

[Alan B]

Regen as Braking

It really depends on your controller. With the Cromotor and a Sabvoton controller setup on the Borg I have variable ebraking that works down to a near stop, and it has the considerable torque capacity of the Cromotor. There's no need for a conventional rear brake, and the front (dual disk) is used to go the last couple mph to dead stop and of course for true emergency stops. Brake pads last for tens of thousands of miles, at least I've never worn any out.

Most controllers have limited regen, on/off to a single setting that is not variable much if at all.

So it depends on your controller, and on how much braking torque your motor can produce. Hence the varied answers.

 

[motomech]

I see, thanx for the explanation.

 

[amberwolf]

As another example for braking:

On SB Cruiser I have a generic 12fet that sort of does a bit of regen, using a 9C 2807 in a 20" wheel. Not enough to notice. But the same controller on an MXUS 4503 in the same 20" wheel makes some decent braking, probably because of the nearly doubled stator/magnet width and the different winding.

A similar 12FET (same MPU, different "brand", apparently different settings or programming) on the same trike (right wheel vs left), with an X5304 has "active braking" or "EABS", which actively powers against the rotation of the wheel, and even with the regular regen on the other wheel at the same time provides so much braking that it pulls the trike to the right.


Unfortunatley both of them are just on / off braking, not proportional, so the harder braking is quite sudden and I can feel myself slide forward on the seat a bit when I brake.


Using an old Ecrazyman 12FET on the MXUS, I get a lot stronger regen (almost equal to the active braking on the X5304), and the range of speed it works at is different than the other generic, too.

 

[d8veh]

First thing is the battery. Unless your battery has high discharge rate cells, it won't be able to provide enough current and will cut out. You'll need a battery that can provide more current than the sum of the maximum currents of the two controllers. That would be at least 30 amps. The average 36v 11Ah battery will struggle at 20 amps.

My preferred method for 2WD is to have a single throtle connected to both controllers and a Pedal sensor for just the rear, so for normal riding, you use just the one motor with speed/power controled by a decent PAS system, but when you want more speed or power, you use the throttle. That means you want a nice modern controller with LCD for the rear, but for the front, just a basic controller. Note that the throttle must only take power (red and back wires) from one controller, and the signal wire is split to go to both. It's the same if you want to use the PAS for both motors, and you should connect one brake sensor to each controller if you use them.

You have to choose the motor speeds wisely. If you want speed and climbing, you should have a low speed motor for the rear and high-speed for the front.

 

[rojitor]

Crystalyte had a few years ago a controller for two motors. I considered it when I was planning my 2wd but I decided not to buy it. The amps were shared by the motors evenly so the real power on each motor was really low. Besides I needed the front only for steep hills so a small controller and a tiny lipo pack at the front were the best solution. It worked really nice for a long time. Then the powerful motors era started and I went back to rear motor setups. Unless you need to carry heavy weight I see no need for 2wd anymore.

 

[amberwolf]

I had a version of one of those, and internally it was just two little 6FET controllers bolted to one heatsink, with the throttle and brake wires paralleled. (only one throttle and one brake input).

I don't know if all of those controllers were made the same way.

 

[73nosleN]

Fairly recently BMSBattery offered a single controller for two motors. IIRC they needed to be similar motors. Never heard or seen any mention of it whatsoever anywhere, So, if you get one make sure and let everyone know if it sucks or not.

 

[d8veh]

Fairly recently BMSBattery offered a single controller for two motors. IIRC they needed to be similar motors. Never heard or seen any mention of it whatsoever anywhere, So, if you get one make sure and let everyone know if it sucks or not.

That was also two controllers with single connectors for PAS and throttle, and a single LCD. You can do that yourself simply by joining the wires of two controllers. Whatever they said, you didn't need two similar motors. They still sell them here:


https://bmsbattery.com/ebike-kit/607-s09pp-72v35a-1kw-torque-simulation-dual-driving-controller-ebike-kit.html

 

[DanGT86]

Bringing back an old thread rather than starting a new one.

I ended up with 2 of those rental scooter motors. The tiny hub motors that are in the 8" tire. I was thinking of machining the wheel off of them and combining them into one big outrunner. If I synch the stators mechanically aligned with each other paying attention to the winding pattern will they run effectively on a single controller as if they were one big motor?

I have an extra controller laying around but don't want to spend any money on these free motors. It would be a fun little machining job so essentially free.

How exact do motors need to be aligned to make this efficient?