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This is very cool...
Cant wait to see your resoults with no load on first and load on second motor.....
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This is very cool...
Cant wait to see your resoults with no load on first and load on second motor.....DJI Drone Advanced Pilot
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Here are the test results with the first 540 XL under NO LOAD and the second 540 XL loaded by using a prop turning in a water filled test tank. The picture shows the test set up.
Here is the video of the tests and you can see it appears in this particulat test set up that it appears to work quite well.
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Very interested in this... I have a quad motor project stewing on the back burner, would be great to only have to use 2 ESCs - doubt I could get all four through one ESC...... who knows?"Look good doin' it"
See the fleetComment
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Try loading the unloaded motor (pinch the shaft?) while performing the same test. Will the submerged prop motor respond by slowing down to match the problem (pinched) motor? This is way cool......& much cheaper than frying my own. Keep up the good work!
Legend 36 sailboat, KMB Powerjet Ed Hardy Viper, ABC jet pwrd BBY Oval Master, ABC Hobby Jetski, NQD Tear Into's, HK Discovery 500, MickieBeez pwrd Jet Rigger!, Davette/Gravtix jet sprint, KMB Powerjet Pursuit, NQD pwrd Jet Catamaran!,Steam pwrd African Queen, Sidewinder airboat, Graupner Eco PowerComment
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Exactly the point I was considering........... My test plan is as follows so stay tuned today:
1. Continue tests with 540 XL' on on Seaking 180 with Eagle Tree set-up. Some say the motors will stall if you accelerate fast. Some say the amp draw will be way too high, etc. Myth busters here I come....................
2. Try the same set up but the two new Leopard motors 4074 at 2200KV each. Again, using the Eagle Tree, look at what happens as the loads become more and more mismatched, etc.
3. Build up jumpers to do 3 and 4 motor testing. Fortunately I have 4 new matched Leopard 4074 motors an this will be my focus on testing. I do not have a third 540 XL or I wouild start with this on the three motor set-up. (I do have 4 of the match brusless motors so that might be my quad possibility.
Again, I a looking at s very specific motor/ESC combination. I cannot imply this will work on All brushless motors and All esc's. I am doing these tests to see if the old beliefs that" it cannot be done" is really a valid statement and at this point am only interested in a combination of motors and esc's that I will be using on future projects.
THE BIG CONSIDERATION IS THAT THE TOTAL AMP DRAW OF THE MOTORS WILL NOT EXCEED THAT OF THE ESC'S RATED CAPACITY. This concerns me with the Leopards because I can pull 140 amps with the Leopard in my Insane Hydro with the Seaking 180. Two motors pulling 240 aps out of a single Seaking 180, well, priceless.............................all the way to the trash bin.Comment
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Just found a post of a different site by Bernie Wolford of Castle Creations. His recommendations are in line with my test results so far.............
His previous comments on running two motors on one ESC..................
1. Two motors can run on a single controller -- but:
a. They must be very closely matched -- within 1% or so on Kv 1. If they are not perfectly matched, timing from the controller is AVERAGED between the difference on the two motors (this happens because the back-EMF voltages average when the wires are paralleled on the motors.) 2. This will cause higher surge currents to the motors-- and will tend to increase the temperature of the controller and motors.
b. They will not always start correctly (I have never had this problem but I only started the motor combinations about 20 or 30 times without a single non-start)
1. If they don't start correctly (for example, one motor starts, and the other does not) the controller can be damaged.
2. So, if two motors are run, they must be started on the ground, and there should be no attempts at restart in the air -- AND if one motor fails to start, the power should be shut down immediately.
So, my personal recommendations are that:
1. We recommend using two controllers to run two motors.
2. If the user runs two motors on a single controller, the controller should be derated by 30% (for example, a 45 amp controller should be used in an installation which draws no more than 31 amps on both motorscombined.) (This is really interesting to me and indicates that the Seaking 180 would be derated to a 126 AMP ESC and I can live with that. I just assumed it would be derated by 50% to a 90 amp ESC so this is actually good news)
3. If two motors are run on a single controller, the motors must be the same type and wind, and must be well matched.
4. The motors should be started on the ground, and not restarted in the air.
5.High inertia loads (for example, large props on very small motors through gearboxes) shouldn't be attempted in a dual motor installation.Comment
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This is very interesting and I commend your testing and posting of results. My issue is this, there are enough problems with esc's going south with just one motor connected to it and run within the esc's known parameters. Why chance problems when running 2 motor on one esc?Steven Vaccaro
Where Racing on a Budget is a Reality!Comment
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All good points, Steve. I have found the SeaKing 180 and Leopard 4074 motor combo a bullet-proof system and I want to push it to the next level for several special projects.
The pictures show just one of them, a prototype of a Military, Hands-Free, Diver Propulsion System. Size is critical. If properly done, the RPM thus power and torque of the motors is perfectly matched.
Also just thought the FE community might be interested in the successes as well as failures of my testing in this area.Comment
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This should cause a bit of controversy....................
I am using a new unit of measure in my analysis that I do not think has been used before. The unit is RPM/watt. To determine this I have an Eagle Tree system on my test rig meauring watts, amps, RPM and temps. I will not bore anyone with the details just the punchline:
This is for BOTH motors unloaded condition:
1 motor 1 esc the result is 292.17 RPM/watt
2 motors 1 esc the result is 343.6 RPM/watt
The 2 motor set up takes into account that you are spinning two unloaded motors each at 11,300 RPM consuming 65.17 watts. In the single motor, single ESC set up you are turning a single unloaded motor 12,350 RPM and consuming 42.27 watts.
Now I really have to think about what this means.....................Comment
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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.
DouggieComment
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I think your testing is great but is it still not cheaper to run two esc's than one big one? The price gets crazy the bigger you go which has never made since to me. You can't tell me it cost the manufacturer double to produce a 240a versus a 120a........FE BOATING: Less like a hobby and more like an addiction!Comment
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Agreed,BUT, starting in the lab has already disproved many theories. It also alows me to closely measure what is happening. Too often when running a boat we "Think" it looks a little better bur just how much, Well????
The absolute most important reason is RAIN. It is, has been and will continue to pour down rain here in So Ca. These are some of the worst rainstorms I have ever seen. Winds are so high it blew my 16 foot electric boat away from the dock. Fireside testing with a gin and tonic...........that's for me in this weather!Comment
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Is it? I buy the Seaking 180's for about $80 each. From Hobby King you can buy the 200 amp HiModel or Suppos for less than $50 and DIY water cooling. Another thing is that in some of my projects this concept 1 ESC, multiple Matched brushless motors may have some real advantages, cost issues aside. What about running a quad system with 4 of the Turnigy outrunners at 400 watts each on a single $50 to $80 Esc? May be a terrible idea, but it sounds at least interesting to me.
I generally try to avoid the conventional and experiment with different concepts since much of it has application to other marine products. Multiple brushless motor control, with matched motors, is right now a potentially interesting concept to me. I am still trying to think about what RPM per watt really means when we evaluate this type of system. Ideas?
I have attached pics of a QUAD controll jumper set I just made. I have 4 matched outrunners I would like to try them on. Using these jumpers I can run `1,2,3 or even 4 matched motors from a single ECS................or blow up that number also!Comment
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