Two Brushless motors on One ESC….YES!

[questtek]

Very interesting thread, BUT real world conditions on an FE boat would be interesting, not a lab experiment, but I also commend you for trying it out.

Douggie

Just so you don't hit me with the Blarney Stone here are a few pics:
a. Mean Machine with twin Leopards and twin SeaKing 180's
b. Outside conditions in the rain and high wind
c. Test set up with dual Leopards and one Seaking........

Should I PM you my address so you can send that Scotch?

[mm123521]

questtek

If two motors are connected in parallel, then small differences in the way the motors are matched will cause large currents to circulate from one motor to the other. These motor to motor, circulating currents will cause a loss of efficency and motor heating.
Small differences in the way the motors are matched include: slight differences in the KV rating, the way the wires are routed to thier slots, small variations in the placement of magnets, slight differences in the strength of the magnets, etc.

Any mismatch causes a small difference in the magnitude and waveshape of the back EMF. This difference in voltage is expressed along the very low resistance path from motor to motor, and may result in a large circulating current. It is this circulating current that causes loss of efficency and motor heating.

Ok that was the technical Bullshop.
It all depends on how well the motors are matched.
questtek: look out for excessive motor heating during your tests, I'am interested in your results

Cool experiment!!

Mark

[keithbradley]

I think when blackcat refered to the higher cost of larger escs, he was refering to escs that are higher current capable than the t-180. The t-180 is kind of an in-between. Compare a Swordfish 120 here at OSE ($69) and a Swordfish 240 ($259). He does have a piont about the more capable escs being considerably more expensive.
Steven had the 200A Swordfish's made for that very reason, but I think that esc (or the t-180) would be well suited for ONE motor like the 4074/2200kv, not two.
If you were going to run a pair of Leopard 4074's (2200kv), you would expect to use a higher Amp esc than 180, right?

I think it would be cool to use one esc if it were the more cost effective choice. I hate all the extra parts. One esc would make things a lot cleaner.

[blackcat26]

I think when blackcat refered to the higher cost of larger escs, he was refering to escs that are higher current capable than the t-180. The t-180 is kind of an in-between. Compare a Swordfish 120 here at OSE ($69) and a Swordfish 240 ($259). He does have a piont about the more capable escs being considerably more expensive.
Steven had the 200A Swordfish's made for that very reason, but I think that esc (or the t-180) would be well suited for ONE motor like the 4074/2200kv, not two.
If you were going to run a pair of Leopard 4074's (2200kv), you would expect to use a higher Amp esc than 180, right?

I think it would be cool to use one esc if it were the more cost effective choice. I hate all the extra parts. One esc would make things a lot cleaner.

WHAT! Someone is on the same page with me? Whoa

[Fluid]

I am amused at all the comments implying that this cannot be done. The most experienced ESC maker in the world - Schulze - has made it clear for many years that you can run two motors off one ESC. The following statement has been in every future model instruction sheet I've seen for at least seven years. I guess some folks feel they have to re-invent the wheel every few years...

9.4 Multi motor operation
In general terms we do not recommend operating multiple motors with a future. From some of our customers we have heard that this certainly works with some (but not all) Aveox, Hacker, Kontronik or Lehner motors, provided that the currents do not exceed the permissible maximum values for the speed controller concerned.
However, we cannot guarantee that both motors will rotate over the full load range. It is never permissible to run more than one Plettenberg or Köhler (Actro) motor connected to a single future: you must use a separate future for each motor. However, you can certainly power both controllers from a single drive battery - provided that you use short power leads and/or inline soldered batteries in a cup.

Caveat Emptor



.

[LiPo Power]

I will not say anything negative about this project because I never did any testing on this subject.
I will say this:
SUPERFANTASTIC!!! Please continue and post your info and videos.
This is such a great thread I can’t stop checking for your new posts. What I like about this is the fact that you can proof some people wrong on their untested opinions…
Wicked!
Cheers
Robert

[Flying Scotsman]

I will not say anything negative about this project because I never did any testing on this subject.
I will say this:
SUPERFANTASTIC!!! Please continue and post your info and videos.
This is such a great thread I can’t stop checking for your new posts. What I like about this is the fact that you can proof some people wrong on their untested opinions…
Wicked!
Cheers
Robert

Typical response from a Canadian from Ontario!!!...Doby, you have to have a heart to heart talk with this dude and get him on the same page...Remember the Avro Arrow...love you all, I think and Merry Christmas and a great thanks to the experimenters in this hobby, as we all learn from their endeavours

http://www.fighter-planes.com/info/arrow.htm

Douggie

[BakedMopar]

FWIW we own a silk screen and textile shop. Our big Hopkins dryer uses two brushless motors controlled by one speed controller. Not sure if that would matter as it's not "FE"

Very intersting conclusions and looking forward to your following tests.

[Jesse J]

I am amused at all the comments implying that this cannot be done. The most experienced ESC maker in the world - Schulze - has made it clear for many years that you can run two motors off one ESC. The following statement has been in every future model instruction sheet I've seen for at least seven years. I guess some folks feel they have to re-invent the wheel every few years...

9.4 Multi motor operation
In general terms we do not recommend operating multiple motors with a future. From some of our customers we have heard that this certainly works with some (but not all) Aveox, Hacker, Kontronik or Lehner motors, provided that the currents do not exceed the permissible maximum values for the speed controller concerned.
However, we cannot guarantee that both motors will rotate over the full load range. It is never permissible to run more than one Plettenberg or Köhler (Actro) motor connected to a single future: you must use a separate future for each motor. However, you can certainly power both controllers from a single drive battery - provided that you use short power leads and/or inline soldered batteries in a cup.

Caveat Emptor



.

1st - I am lovin this thread
2nd - I have 2 basic questions...

what's a "future"?
what's an EMF?

sounds like the trick here will be to not push things and have lots of cushion. I have noticed pronounced rpm differences on turns in my twins, I am glad I am not an ESC, this could cause a pretty good work out having to manage two motors behaving so differently - I would expect this wide variability would be the problem causer. Maybe even more so, the fact it only happens for short periods - fluctuating fluctuations. I wonder what second order fluctuations will create in the electrical system.

[teach]

future is the name of thier speed controls.
Future=schulze
Hydra=castle

EMF is way over my head to explain.

[CornelP]

EMF= electromotive force or electromotance...

http://en.wikipedia.org/wiki/Electromotive_force

That's the theory behind it... a good explanation is also here:

http://www.brighthub.com/engineering/mechanical/articles/75825.aspx

[questtek]

Video of lab test tank testing with twin 540 XL's and then with twin Leopard 4074's.

http://www.youtube.com/watch?v=O0iMQ9rQNuo&feature=youtube_gdata

Please remember, this is an experiment that will be followed up with actual boat testing. I do not endorse this technology only point out what can and cannot be done based on actual experiments with real numbers.

Seems like many people, based on their comments, feel this has absolutely no merit what so ever. That is possibly correct but I do not quite know that for sure at this time based on what I have seen to date. I may in a few more days when the rain stops and I can do some lake testing I should know a bit more..................possibly.

Many more people see no application for this. I know I will get pounded but consider the possibility of a quad brushless motor drive for a FE for less than $100. How?, I have a Hobby King 200 AMp ESC for $29 and four of their 600 watt Turnigy H2223 motors at $13 each. Add the carbon props at $1 each and some couplers at $2.50 each and I believe you will be still under $100.

Would this be an interesting build for the right boat? Would it work? Would it handle well? Would it go fast? Would it sound cool? The numbers say it can be done in terms of loading but will it actually smoke as soon as the power is turned on? I do not know the answer to any of these questions.............still the concept intrigues me.

[m4a1usr]

No matter how your sperament'n turns out its nice to see you pursuring this. Real world testing is what pushes things along. Keep up the good work and dedication!

John

[questtek]

No matter how your sperament'n turns out its nice to see you pursuring this. Real world testing is what pushes things along. Keep up the good work and dedication!

John

As they say.............You can always tell the pioneer, He's the one with the arrows in his back!

As an update I tried multiple Turnigy $13 outrunners running on one ESC and it was a failure. They have a 4400 KV and, because they are a cheap motor, the KV varies from motor to motor. Trying to drive mis-matched motors, as I have previously found, does not work. There is a lot of sputtering and juttering at lower speeds and ocassionally they do link up at higher speeds. Don't think this is a realistic to run cheap, KV mismatched motors on one ESC although my testing continues on the larger, higher quality inrunners and outrunners.

[FighterCat57]

Science, Math, Myth, Legends and Opinions. This is a fun read.

I'm really curious as to how your experimentation turns out Joe.

PS- Fluid, it's no fun for the ego having a perfect wheel handed to you.