MMM: No brushed motor limit?
 

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!

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

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.

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.

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.

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

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...)

K, thanks! Glad I asked.

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

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

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"? :wink: :whistle:

:surprised:i always tinking that the mmm was very powerfull only 120amps:oops:....:whip: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:gasp:

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. :smile:

I don't think there is a company named Novak. Wait, lemme check...:oh: there is!

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? :whistle:

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

Most of the other esc's are tested different from castle, some are even theoretical. But i'm pretty sure castle tortures theirs. I was running two MM's, one 7XL on 5s and the other 9xl on 5s, while the esc's got hot, they never flinched or thermalled. Hats off to castle for making two of the absolute best esc's made. Now that most of the problems are sorted out, It may be time for me to get one (at least) of the MMM's. I plan one for my 1515/2.5d and the other for a 2250 lehner, Possibly in a Summit :mdr:

I think most ESC makers simply lump the FET current ratings together and that's the current rating. But, anyone who takes a few minutes to look at a datasheet will see that those ratings are usually at 25*C (77*F). I tend to shoot for temps around 30*F above ambient max, so I'd have to run at 47*F ambient just to meet the FET temp ratings, and that is assuming adequate airflow on a perfect heatsink.

From what I've seen, Castle tends to rate their products at temperatures found on earth during normal running. Like their HV110. Even at around 160*F FET temps, the FETs still are capable of ~140A looking purely at the temperature derating curve. To match other makers' specs, they would have to rate the HV110 at something closer to HV180 or more.

I can see this helping Castle, and hurting them at the same time. A newb looking at the specs printed on the box will assume the other ESC is better because of the inflated ratings. Anyone "in the know" will see through that BS and figure the ESC is properly rated, but how many people fit that profile (think: the typical trx member)?

I think Castle should put some type of dual rating system on their boxes. One showing the real and proper rating, and one stating the rating if using other manufacturers' rating methods.

thanks BrianG!!!!!i learn every day when i read your thread:yes:but if i completely understand a lot of esc are overrated!!???a the castle esc are simply correctly rated????and for the mmm it doesn't mean that the esc seem to handle a lot of power!!???

Yeah, other ESCs tend ot be "optimistically" rated, while Castle seems to be more realistic.

Gotta remember that the MMM is capable of 120A and 6s - that's 2664w of power, or over 3.5HP! So, yes, it handles a lot of power. :wink:

"Brand L" -- their new 1/8th scale controller shuts down in just a few seconds on our MMM bench test -- where the MMM will run continuously (at 120A...)

thanks for the edit pdelcast:oops:however im not afraid about the fact that the mmm handle ''ONLY''120amp:mdr:

I did close to that with an MGM 16018 and a 2250 lehner (2584W peak to be exact) In my twin force, that is some freaky nasty power

Indeed. :lol:

My hands were shaking uncontrolably the first time i dropped the hammer on that setup, what a rush :slap:

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

Try running a couple of these in parallel!!! THAT would impress me! :lol:

http://www.robotmarketplace.com/prod...G-S28-150.html

Dang!!! 3.5lb motor!! Don't drop that on your foot...

Machined 6061 case, 1/2 steel shaft, 1/4" thick NdFeB magnets and a 4-pole armature! To top it all off, 82% efficiency! I love these things! :lol:

I used one back in HS in a Battlebot my shop class built. It spun up a 24 pound steel bar to 2000 RpM (3:1 chain drive) in about a second. :surprised:

What did you call this spinning bar o' death? The shin basher? Sounds like something fun to chase drunks with... watch out Shaun (tdc57)!!!

It was called "Stop Bot" because we used a 1/4" thick piece of 6061 as the top that was the exact dimensions of a stop sign and painted just like one. It was about 8" tall and the steel bar extended down the sides.

http://i52.photobucket.com/albums/g4...d/DSC00218.jpg