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View Full Version : Which number of poles is best for 2 motors on 1 ECS ?


cyclops2
04-08-2008, 01:42 AM
There must be some that are better than others.

Dorsal
04-08-2008, 02:39 AM
If you are talking about brushless motors, there is no way to properly run 2 motors on 1 ESC. The ESC relies on the inductance feedback from the motor to "tell it" how to control the motor. If you have 2 motors,there are 2 different inductance feedback pulses and the ESC can't control both motors properly (if at all). Spend the money and get a second ESC.

Kosh
04-08-2008, 03:02 AM
I'm not buying into that at all, I have built 3 twins now and all used the 2 motor 1 ESC setup without problems.

This kit has sold for many years on the same setup. http://m-a-e.com/Sub_Pages/Products/JINX%20Kits.htm

Westport "Black Widow" Twin Brushless CD-ROM Direct Drive Outrunner Motors
Pre-wired (plug-and-fly) for twin-power applications. Male Deans 3-pin micro connector is already installed. Mating female Deans is provided for your ESC. Motors have same spec's as our 20T Westport listed below. Recommend 8x4 props on 2S or 7x3.5 props on 3S. Generates 16-21 ounces of thrust and weighs just 38 grams! Run these setups on a single T'bird-9 or Phoenix-10 ESC

62131

Kosh
04-08-2008, 03:03 AM
That didn't answer your question and I'm unsure what to tell you about poles.

ron_van_sommeren
04-08-2008, 03:22 AM
It should not work, it can work and if it works, the motors are in *perfect* sync. Both motors should be identical/equil, the 'identical', the better. Ditto for wire length and props. www.kontronik.de had a twin set in their program.

As for the number of poles, that's not relevant, the controller only 'sees' number_of_poles * rpm. But I think its safe to assume that the higher that product, the more difficult it will get to get twin set working.


Vriendelijke groeten ;) Ron

Dr Kiwi
04-10-2008, 03:36 AM
I'm not buying into that at all, I have built 3 twins now and all used the 2 motor 1 ESC setup without problems.

This kit has sold for many years on the same setup. http://m-a-e.com/Sub_Pages/Products/JINX%20Kits.htm (http://m-a-e.com/Sub_Pages/Products/JINX%20Kits.htm)

Westport "Black Widow" Twin Brushless CD-ROM Direct Drive Outrunner Motors
Pre-wired (plug-and-fly) for twin-power applications. Male Deans 3-pin micro connector is already installed. Mating female Deans is provided for your ESC. Motors have same spec's as our 20T Westport listed below. Recommend 8x4 props on 2S or 7x3.5 props on 3S. Generates 16-21 ounces of thrust and weighs just 38 grams! Run these setups on a single T'bird-9 or Phoenix-10 ESC

I tested this set-up for Jeff Krebs and got very mixed results - sometimes both motors would start and run, other times only one would start. I tried different ESC's and I must say the TB9 or a Scorpion worked best. My CC 10 had real trouble. Perhaps if one could play around until one found the perfect timing setting, and played with soft or hard start.... it might work out, but I still reckon 2 ESC's is less of a hassle/crap shoot.

praymond
04-10-2008, 05:48 AM
Boy I've seen this discussion many times! Personal experience is on small cd kits ( strongrc kits), and I've had problems starting on CC10's, but absolutly no problems on a Thunderbird 9. This is running 19t kits on 8040 props on a 2 cell, and 16t kits on 7035 props, on either a 2s or 3s. I love reading the nay-sayers.

I think the secret is as stated, the motors must be indenticaly wound

Just my 2 cents

Paul

cyclops2
04-10-2008, 09:10 PM
We are getting there.

Are the Thunderbird 9's a SOFT starting ESC ?

In the industrial brushless drives you can run more than 1 motor off of them.

BUT.

There is no way you would EVER have a fast start. So I am going to see if the real secret is the safety slow start that is built into some ESC's. ????

praymond
04-11-2008, 01:43 AM
Hmmm, I don't seem to recall any difference in startup speed with the TB9 on 2 motors, or a CC10 or TB9 on one motor. Here's one foamie I put a pair of cd motors on. I haven't used anything bigger than these motors, and a TB 9 tho.

cyclops2
04-11-2008, 03:01 AM
Then we are back to they are designed with better circuits.

There is nothing else if the loads, motors, are the same.

Who sells the TB9 at a good price ?

Kosh
04-11-2008, 04:39 AM
Heres my take, If around 9 out of 10 times starting both at the same time is fine thats good enough for me. Granted there were a few times both did not start so its not 100% but what is anyways. A fast simple throttle down and back up would normally fire up both again. I've only done this with smaller motors and foam plane so if your running something bigger I would always opt to run a pair of ESC's. On the small foamies and motors they seem to work just fine, Its not often I would glide a twin but there were a few times only one motor fired back up, Reset and both would fire. Even on 1 motor the planes would still fly as I lost a few props on some GWS BN-2s and landed fine on them. Its not for everyone but does work.

ron_van_sommeren
04-11-2008, 12:31 PM
... In the industrial brushless drives you can run more than 1 motor off of them. ...Industrial brushless motors/drives are a different breed, they are not BLDC motors, they don't use BEMF for rotor speed/position detection.

Prettig weekend ;) Ron

cyclops2
04-11-2008, 11:58 PM
Actually, American companies have run them on back emf for over 15 years. Cheap design for non- accurate position and speed under loads.

Variable speed fans & mixers are common uses.

Old Sloppy
04-12-2008, 06:22 PM
Two pole motors work the best with a single ESC.

multi poles tend to cogg more.

I personaly prefer two ESC's.

Harry

kyleservicetech
05-14-2008, 03:36 AM
I did this several years ago, using two identical go-brushless motors. As I recall, these motors turned an 8/6 prop, pulling about 17 Amps. (They were wound with double formvar wire from work)

The setup worked pretty good, however, for some reason, when turning two motors, the shaft RPM dropped about 1000 RPM from running only one motor from the same ESC. Battery voltage was not an issue, since I was using a 30 Amp 10 Volt DC regulated power supply.