2 5700 motors on mamba max? - RC-Monster Forums

scramblingmaxx · **2 5700 motors on mamba max? -** 03.03.2007, 09:18 PM

Hi gang ,sorry if this has been asked ,can you run 2 brushless motors on ecs, building a stampede 4x4 useing 2 transmissions so need 1 motor for each,I know ,Get an emaxx ,but i'am nitro guy, bigblock tmaxx's, already have sampede,s doing it for kicks. looked thru forum to see anything about it

BrianG · 03.03.2007, 09:34 PM

I wouldn't. One motor can get the ESC pretty warm depending on application, so I imagine two might be too much. Plus, the ESC might have trouble sensing rotor position unless both motors are prefectly syncronized.

Welcome to the forums BTW!

scramblingmaxx · 03.03.2007, 09:38 PM

Thanks didn't know if it would .wanted it to scream, i guess evx will have to do.

MetalMan · 03.04.2007, 12:21 AM

You could run a Mamba Max ESC with two brushed motors :).

bdebde · 03.04.2007, 02:58 AM

It actually may work; as you are not driving a common spur with both motors, no worry about synching them.

BrianG · 03.04.2007, 03:04 AM

Well, I would think two BL motors would have to be synced or the ESC might be confused at the different rotor pulses. I think you should try it and let us know. :dft012:

bdebde · 03.04.2007, 03:10 AM

I have seen it done somewhere on a common spur (can't find link), they had to power up to synch motors before attaching pinions.

bdebde · 03.04.2007, 03:15 AM

Found this:

To set up for twin BLMs operations:

1. Make 3 sets of Y-lead out of heavy gauge wire.
2. Insert the pinion gears onto the motors shaft. Do not tighten the set screws at this stage, the pinion gears have to be free to rotate on the motors shaft.
3. Mount the motors onto the model.
4. Connect the Y-leads to the motors and ESC. Please take note of the connection in accordance to the colour of the wires.
5. Run the 2 motors together at low to medium speed for a couple of seconds. The spur gear should not turn as the pinion gears are free to rotate on the motors shaft.
6. Disconnect the battery.
7. Apply some good quality thread-lock to the set screws and tighten the set screws to the pinion gears. Be extremely careful not to turn the pinion gears, spur gear or the motors shaft as they must remain at the position where they stopped.
8. Use an oscilloscope to confirm that the voltage generated by the 2 motors is in phase (as shown in the photo). The ESC will now treat the 2 motors (or even more than 2 in other applications) in sync as a single unit.
9. A less accurate method is to use a Multimeter (set to AC current) to check the phase-phase current between the 2 motors. Disconnect 1 set of Y-lead and connect the Multimeter probes to the original lead of the 2 motors. The current measured should be in the order of 0.1mA if the spur gear is turned by hand.
10. You must use step 8 or 9 to confirm your setup. The ESC can still run the 2 motors even they are way out of phase. In such case, large amount of current will flow between the 2 motors and if you turn the spur gear by hand (with all 3 Y-leads connected to the motors but the ESC disconnected), you will feel a braking effect or resistance (The motors are now acting as generator and motor in turn).
11. Other considerations:
(i) The backlash of the gear train may affect the phase angle of the 2 motors.
(ii) The close proximity of the motors may cause cross coupling by stray magnetic Flux.

So, looks like running them will synch them up?

BrianG · 03.04.2007, 03:15 AM

They did it on one ESC? I know I've heard of 2 BL systems on one truck...

bdebde · 03.04.2007, 03:34 AM

Yep, one esc.

Mr.lst · 03.04.2007, 05:25 AM

guess you learn something new everyday

BrianG · 03.04.2007, 02:03 PM

Cool. So, it's possible. But after feeling how warm my MM esc gets with just one motor, I think it would thermal with two. I would suppose you'd have to use an ESC with a hefty current rating.

03.04.2007, 03:03 PM

MMM with mm motors :D

BrianG · 03.04.2007, 06:14 PM

We'll see. I won't believe half the hype of the MMM until I see it and run it. Speculation tends to inflate the specs...

BP-Revo · 03.04.2007, 06:39 PM

They must be in the same phase though, thats the only thing. This will be very hard to do with the pinion on the flat spot.

I have seen someone run a 8XL on a HV-Maxx ESC. He used the HV motor just for the sensor to detect rotor position - but the 8XL was doing all the pushing. He ended up with 8XL power with sensored operation. Was pretty cool (but alot of weight). But weight could be reduced by using a different (smaller) Novak motor than the HV.

Also, if I'm not mistaken, even if the phase was slightly off, it still worked due to the HV only sensing rotor position at low speeds. Once it gets going it switches over to back-pulse sensorless style operation.