MMM: No brushed motor limit?

[BrianG]

For any CC engineer:

From the CC special projects page, the MMM is listed as having a 120A capability in brushless mode. Since the ESC is a basic H-bridge setup, that should mean in "brushed-with-reverse" mode, it should have the same 120A rating. And in "high-power brushed mode", it would be 360A. Is this correct?

Also, the specs say "no brushed limit". I assume you mean there is no turn limit for any single brushed motor. But, if several brushed motors were used in parallel, what is the limit? I would imagine that as long as the draw was under 120A, things should be fine?

Thanks!

[e-mike]

Originally Posted by BrianG

From the CC special projects page, the MMM is listed as having a 120A capability in brushless mode.

Thanks!

i know that im off topic...sorry for that... but the mmm is not rated for 200amp continiously??????

[What's_nitro?]

If my understanding of an H-bridge is correct, in order to see the 360A rating, you would need an external ground directly back to the battery. The controller's bridge would not be able to conduct through the motor both ways (internally) if all three FET banks were being used to realize the 360A output. I'm sure I'm missing something here...but it sounds correct in my head.

[BrianG]

Originally Posted by e-mike

i know that im off topic...sorry for that... but the mmm is not rated for 200amp continiously??????

Not unless the "special project" MMM is different than the regular one. Could be I suppose, but I haven't heard anything that said different. The 200A rating was just a rumor AFAIK during the time where it was still in development and everyone was speculating on its ratings.

Originally Posted by What's_nitro?

If my understanding of an H-bridge is correct, in order to see the 360A rating, you would need an external ground directly back to the battery. The controller's bridge would not be able to conduct through the motor both ways (internally) if all three FET banks were being used to realize the 360A output. I'm sure I'm missing something here...but it sounds correct in my head.

This is how I see it: The MMM has 36 FETs. 3 phases of 6 FETs for the positive supply, and 3 phases of 6 FETs for the ground connection. At any one time, 6 FETs are conducting power to a coil, and 6 are conducting to ground at the other end of the coil.

In brushed mode with reverse, one phases is not used at all, so the same basic operation as above is used.

In high-power brushed mode, the battery + wire goes directly to the motor + terminal, and you tie all three phases together for the ground wire. Since there are 3 phases of 6 FETs on or off at once, that's 120A X 3, or 360A.

[What's_nitro?]

Originally Posted by BrianG

In high-power brushed mode, the battery + wire goes directly to the motor + terminal, and you tie all three phases together for the ground wire. Since there are 3 phases of 6 FETs on or off at once, that's 120A X 3, or 360A.

Yes! I just thought of it with inverse polarity (external gound, not external positive).

[Pdelcast]

In brushed mode about 100A for forward/reverse (and that's a REAL 100A continuous, not a BS 20 millisecond rating like "Brand N" would give you.) The limitation is really from the 10ga wire -- 100A is about the limit for a single 10ga.

A good quality brushed motor will melt at about 40A continuous, and will really only handle about 25A or so on a continuous basis... so you should be OK with up to 3 540 size motors in parallel.

In high power mode, you should be able to run a little over 200A continuous (remember - - Amps doesn't scale linearly because of the I^2 losses...)

[BrianG]

Originally Posted by Pdelcast

...not a BS 20 millisecond rating like "Brand N" would give you...

I just re-read this section and wonder if the letter "N" was just a coincidence, or is it referring to a certain competitor whose name begins with "N"?

[sikeston34m]

Originally Posted by Pdelcast

In brushed mode about 100A for forward/reverse (and that's a REAL 100A continuous, not a BS 20 millisecond rating like "Brand N" would give you.) The limitation is really from the 10ga wire -- 100A is about the limit for a single 10ga.

A good quality brushed motor will melt at about 40A continuous, and will really only handle about 25A or so on a continuous basis... so you should be OK with up to 3 540 size motors in parallel.

In high power mode, you should be able to run a little over 200A continuous (remember - - Amps doesn't scale linearly because of the I^2 losses...)

If 100 amps is the limit for a single 10Ga. Wire, What does this say about the 100 amp + continous ratings of other brand ESC's that are fed with 12Ga. Wire?

[e-mike]

Originally Posted by BrianG

200A rating was just a rumor AFAIK during the time where it was still in development and everyone was speculating on its ratings.



.

i always tinking that the mmm was very powerfull only 120amps....so what is the real amp rate of the mmm (in brushless mode)so i read some thread here and im surprised to read that the mmm can old 100amp in brushed mode and 200amps in highpower mode

[BrianG]

K, thanks! Glad I asked.

[What's_nitro?]

4400W.... Man, that is A LOT of power! It may not blow, but how long could you run that without the ESC thermalling?

[MetalMan]

Anybody got a 24v 6HP brushed motor they want to test the MMM's limits with?

[jordan...]

Originally Posted by MetalMan

Anybody got a 24v 6HP brushed motor they want to test the MMM's limits with?

Send me an MMM and i'll happily test it out

[Dagger Thrasher]

E-Mike, I wouldn't worry about the MMM being rated at "only" 120A. Amp ratings doesn't really mean wnything when comparing car ESCs nowadays. That might sound low next to some other ESCs which are rated at some stupid figures, but the truth is, the MMM can carry a huge amount of power.
If it can handle a 1521 1D on 6S without a problem as Patrick said they tested with, then I don't think current-handling is going to be a problem in brushed OR brushless mode.

[e-mike]

Originally Posted by Dagger Thrasher

E-Mike, I wouldn't worry about the MMM being rated at "only" 120A. Amp ratings doesn't really mean wnything when comparing car ESCs nowadays. That might sound low next to some other ESCs which are rated at some stupid figures, but the truth is, the MMM can carry a huge amount of power.
If it can handle a 1521 1D on 6S without a problem as Patrick said they tested with, then I don't think current-handling is going to be a problem in brushed OR brushless mode.

thanks!!!well if the mmm is able to handle a 1521.......i was scared because the new losi esc can handle 160amps continously!!??and the mmm 120amps