MM/Feigao cogging

I don't own any "good" motors, but from what Mike tells me; going with a good motor like a Lehner or Neu will cut the temps considerably AND you won't need to run a fan.

gixxer, are you really running a MM on 5S lipo? I've been itching to go with a lower kv motor on more voltage, but thought I'd smoke the MM.

[glassdoctor]

I still have a hard time saying it doesn't cog much.... but really it is better. To some it may NOT be acceptable though.

But since I hardwired the motor, I have raced with it and played in the street geared 18/46, and I did several tests rippping wheelies in the house with the eagletree etc. (creep a few inches then grab throttle....)

Occasionally it still has cogged on me unexpectedly... but it's not very often. You just have to be real quick to react... let off throttle and go again.

At that last race... it never cogged once on start up etc. Only thing funny that day was a couple times I got a 'glitch' while at speed. That's not good either but it's not a "neu' issue... I have seen the exact same thing on rare occasions with a box stock MM setup in 1/10 buggies.

I have not run the truggy or 1515 with the motor hardwired yet.... I have a Quark that I finally put in there for now, instead of selling off.

[gixxer]

aangel, yeah I have been running it on 5s. At first i had a 4s and was running the 7xl but then picked up a 5s and went to the 9xl. I still have both motors but only run the 9xl because I got rid of the 4s pack and 5s on the 7xl would be stupid fast in my 8ight.

so far no smoke so I am happy but really dont want to recommend it because its way out of spec. I was actually going to go back to 4s because I didn't think it would hold up but so far so good. Now if they just release the MMM I wouldn't have to worry about it.

OK, after about a week, this is what it boils down to (according to Castle). This is the email that I was sent,

Tony,

ESC's don't have weight limits...batteries have current limits. ;) You
could put a MM setup into an Emaxx and it would drive it if your
batteries could deliver the current. The problem is whether the motor
will overheat in the setup or not...why you can't use the MM systems in
monster trucks. :) Brushless motors will draw as much current as they
need to in order to get the job done...if the batteries can't supply the
current the system cogs. The ways to drop current draw are a lower
voltage battery pack, bigger spur, smaller pinion, or ESC
settings...effectiveness of dropping current is going to be in that
order (voltage, gearing, ESC settings).

Joe Ford
Product Specialist
Castle Creations

I may just be an idiot, but I don't know what to make of it. I can see that he is alluding to the fact that the MM is NOT meant to be run in monster trucks; but then it seems that he's saying that the problem in not being caused by the esc, but rather too much of a current demand. I don't see how the batteries could be causing this problem. I'm running Kokam packs (as I told him in a previous email). If the Kokams aren't enough, then what do I need. He also says that one way to drop current demand is to go with a LOWER voltage pack?

Can anyone shed some light on this? I'm really tired of trying to exchange emails and trying to get someone on the phone.

[glassdoctor]

What to make of it? Spin doctor.... which is why it doesn't make much sense. It's bull#%@! ;)

Castle has this tendency... when all else fails (or they don't have an answer...) blame the batteries. They have been preaching about batteries since the Mamba25 first came out.

It's true that often the battery is the weak point/problem for many of their customers... I think they talk about inadequate batteries so much that they brainwash themselves.

I have been in contact off and on with Castle for months... and still they seems to bring up batteries quite often in babbling with me... then I remind them that for example I run a 12000 mah lipo. They say yeah that's good enough...

Referring to 1/10 cars .... thye have said on the record that a good nimh pack is just fine. (It's the stick packs and junk cells that are the problem)

IMO it's obvious the Kokam 4800 are good enough. They can flow 2-3 times the current of a nimh pack.

By Castle's own words... they say to look at whatever I see on a datalogger for peak amps, and double that for what the true micro-second current is. (they say the sample rate isn't fast enough with basic loggers to register these spikes... personally if such spikes NEVER show up on a 10 sample/sec logger... then I think such spikes don't matter. imo. )

So... even considering that, the Kokam packs are up to the task easily.

Does it ONLY have problems under full throttle lauches from a dead stop?

EDIT... gee I was kinda harsh on castle here huh? hee hee

[BrianG]

The part about lowering the voltage makes sense; running at a lower voltage will reduce the current - assuming of course that motor, gearing, weight , etc doesn't change...

If it's a battery issue, you copuld verify that by lowering the start power, increasing punch control, and reducing the timing - all things that would cause the ESC to go gentler on the batteries.

I'm also wondering if the LVC setting is contributing to this. Even if the battery voltage doesn't drop much, heavy current on the wires, solder joints, or even on the circuit traces could conceivably drop enough voltage to trip the LVC. Has anyone tried shutting off the LVC as a test? Of course I wouldn't run this way, but it's just a test.

[glassdoctor]

I had the LVC off on all those tests I ran... didn't make a difference that I could tell. But I will pay more attention in the future and see if the lvc effects cogging

Most of my cogging problems went away when I made all of the settings on the MM controller as tame as possible. With lipos, it should still rip anyway. I had bad cogging at first, now it only occurs accelerating hard from a dead stop.

This cogging problem that I am having can happen at any thing, when starting from a standstill. From slowly easing on the throttle to jamming 1/2 throttle all of a sudden. It doesn't happen everytime, but enough to be concerned about it. The trouble is that when it happens during the heat of a race or bashing session on the track, I can't always tell when the truck is cogging. I mean that I can't tell if the truck isn't moving because of cogging or if it's hung up on something; and if it is cogging and I give it too much throttle to get going again after a wipe out, I fry the spur gear.

I also don't understand the part about lower voltage getting me less of an amp draw. I thought that given a particular motor, say a 1500 watt motor, the motor can generate the power that is built to generate. So, if I'm running a 1500 watt motor, it would need to draw ~101A to make 1500 watts with a 14.8v pack. If I drop the voltage down to 11.1v, then it would need to draw 135A to make the same power, so I'm thinking that dropping the voltage would make the system draw more amps. Am I missing something or oversimplifying something?

I'm running my system with the lowest timing, lowest start power, and 0% punch control. The punch control makes the truck undriveable on our track. Our track is very tight and technical.

I have noticed that the "problem" gets better and I reduce the gearing. I'm now running a 10T pinion and it's about to a point where I could live with it, but would rather not have to. I have't temped anything yet, but I ran the hell out of the truck yesterday and the esc was noticeably way hotter than the motor, so I'm going to assume that I'm still overgeared a bit.

GD, what gearing are you running on your truggy? I'd imagine that you are running proline MT tires. Maybe the crime fighters, bow ties, or holeshots.

On a side note, GD, you were kind of rough on Castle, but the answer that I got from them was complete BS. Until a very short time ago, I was an avid fan of the Castle products, but I'm starting to change my mind. I can't get support to save my life. I'd imagine that it's because they're devoting a lot of time to the MMM project, but what happens when I need support for the MMM and they're working on the next latest and greatest thing. Am I, again, going to be left hanging for support.

Of course, I still have to keep in mind that the MM was never intended to be used in an 1/8th scale application.

[gixxer]

the only thing i can think of is lowering the punch control.

I did try 100% punch control and this does make it better, but makes the truck undriveable on the track. Our track is very tight with lots of jumps immediately following turns, whoops and what not. Instant throttle response is really needed.

I suppose I'm beating a dead horse with this thread. The combo doesn't work in the truggy. I just have to decide what I'm going to go with.

[gixxer]

I think I have mine set at 40 percent. 0 just made my car uncontrollable.

Anything under 100% punch control doesn't get rid of the cogging. I don't have any problems controlling the truck with no punch control. Not on the track anyway.

[glassdoctor]

My truggy is geared 14/49 with the 1700kv motor... and I have actually run it at 12/46 on the small local track. But 14 is much more fun :)

At 12/46 it barely sniffs 30mph which is really ok for smaller tracks but doesn't have much wow factor.

I ran Bowtie MT tires last summer... and I have run the stock Jammin CRT without a problem. Those are a little smaller and lighter than Muggy ones but not a huge difference imo.

I know what you mean about the cogging, etc during a race... it's much more likely to screw something up in the heat of battle. Not exactly patient and careful during a race. ;)

Lower voltage: In theory this is sorta correct but in reality it's backwards. It's easy to contradict yourself here. One one hand, as Castle likes to say... a motor will "draw whatever amps it needs to get the job done". BUT, it's also true that a motor will draw MORE current if you give it MORE voltage, with all other variables being the same.

Think brushed motors for a second....on 6 cells it runs as "normal".
But what happens if you run the same exact setup and gearing on a 3 or 4 cell pack? It's much slower of course... AND it's going to draw a lot less amps.

Now strap in a 10 or 12 cell pack, again leave gearing etc all the same.... it's going to be ballistic and it will draw a ton of amps.

So really.... the motor doesn't try to pull an infinite amount of amps in all situations. It must have voltage to create power. Other wise, you could hook up one cell to a motor and it should dump like 400 amps???? NO, I don't think so....

Anyway.... yeah I was hard on Castle, but man... those standard BS by-the-book generic talking-to-an-dummy answers really piss me off.

Not to mention the fact that they contradict themselves with some points in there. You can't have it both ways, and when we get answers like that (from anyone not just castle...) it just comes across as talking out their @#$.

The real answer is that they don't really have one. Period. But it's not easy to admit that so we get politcal bs.

[glassdoctor]

Now... I think in general castle has been very good with their service and working with all of us beating on the MM like we do. And, normally they have been very easy to get on the phone. I have only had one time where I didn't get right through to one of them. So I will cut them some slack if they are swamped now and then. I'm still on Castle's bandwagon.... but I'm going to call them on dropping bs. :)