TrueRC 2X3S1P 5000mAh + NEU 1515 1.5D + MMM = FIRE!
 

So.. My latest MMM HAD been running pretty well. Ran several packs on 4S, both TrueRC and MaxAmps. No problems.
Today.. Thought I'd show it off a bit to some guys I work with. Ran 4S for a bit and then decided to try 6S.
6S ran great and just absolutely out of control fast... for about 5 minutes.
It rolled to a stop.. so I ran over expecting to find a dead MMM, but the lights were flashing.. Strange.. I unplugged the batts and repowered it up. Tones sounded, 6 beeps for auto Lipo, final tones and hit the throttle. Body was still off as I suspected something may just be going bad here. Sure enough.. It rolled about 5 feet.. Massive Smoke and up in flames she went.
I can still smell the aroma of baked electronics. I got it all out fast enough that it didn't get a real chance to melt anything (LUCKILY)
Went back into the office and called Castle.. again... Tech support.. and dangit if I can;t recall his name.. wasn't Thomas though.. Any ways...
He inquired to what I was running, etc.. When I mentioned the TRUERC batts he stopped me and said.. "There's the problem! Nearly everyone of these that flame are due to the cheap batteries and TrueRC's are one of them". I told him that I usually run 4S maxamps and TrueRC and he said MaxAmps are much better as they can handle the current draw.
All of this really starts to contradict what goes across these forums.. and I told him that.. He said.. "You can't believe everything on the forums" to which i completely agree, but I do tend to look at feedback from masses and not just a single source. Most of what I read.. says Maxamps are typically over rated and TrueRC are more accurate if not underrated. He said he wishes they could put out better information but they can't regarding batteries and such. I said.. yea.. So do I.. as the only info is what we all share.
anyways.. Just wanted to share.

Yet another MMM down for me.. Now I am out of service and I have bought 2 MMM V2s. I shoulda just stuck with 4S.

My thoughts are the same as they have been, the 1.5d is too much motor for 6s especially in a monster truck.

PLease explain. Looking at Specs of both 1.5d and MMM, I shouldn't be outside of the parameters. and it shouldn't result in FIRE after about 3-5 minutes of maybe half throttle?
In all reality, 6S on that motor, I knew would be overkill, but I wanted to try a run on it. It was the first run.. Brand new batteries even.
I actually purchased the 6S for my Medusa.

What gearing was it running on 4s and on 6s?

21/58 and 16/58 respectively.

Were they the 10C TrueRC cells or the 15C TrueRC cells?

Were the batteries hot when it stopped the first time before the fire?

Seems strange, if the trueRc batteries were and they could not supply the current. I would think that would put less stress on the electronics not more...

On the other hand if the batteries catch fire then we can blame the batteries.


I have an eRevo geared 20/58 with a tekno 1515/1y 220kv and I run 4s 8000ma(15c) trueRc batts. I have yet to hit the lvc and I have driven on the track for ~30 minutes (the charger put 6000ma back in the batteries after this outing)

From what I have read the trueRc are at least equal to maxApms in current output and capacity.

I also would not be surprised to find that statistically more people with the MMM are running trueRc so his observations about failures could be true but not indicate and issue with the batts

15C.

Batteries were NEVER hot nor was the motor at the time of Flame. Motor was warmed up, I think Temp gun was 108, batts were 85, esc.. well On fire.

You are at the top line of spec only assuming adequate airflow. You must also account not just for rated current but stall current, spikes, and so forth.

The motor is rated at 120 amp and the controller at 120 amp with air greater than 500 lfm. Pretty tight when you look at it. Then factor in that with 0-200 lfm you get 70 amps, and 200-500 lfm you get 110 amps, you can see where the problem is.

Running the KV as high as possible is not the best way to get speed in a monster truck, you can't apply 10th scale or 18th scale formula's in a monster truck and/or 8th scale world. You are much better off to get a lower KV motor and gear down to attain the speeds you want. Then there is the fact the having a high speed setup on anything but the street changes the dynamics drastically.

Then there is my final note that your 15c batteries can't provide enough current for that setup. 15c at 5000 mah is 75 amps. You would need at least a 25c 5000 mah pack or at 15c an 8000 mah or higher pack. Cheap packs can damage the ESC as well.

Where I agree with where you are coming from.. And in in all honesty, running the 15.d on 6S is not on my list of normal activities. Brand new batts, Nearly new MMM, not abusive AT ALL. And actually never got past, say half throttle, and there is no way to even punch the throttle on 6S with the 1.5D and geared where I was... Current Draw SHOULDN'T have been real issue.. Setting all that aside...
Where did you find the MMM is rated at 120A? I agree running the 1.5D on 6S is on nearing the upper limits, but it still isn't over. If I was drawing too much current, the batts would have heated up.. or givin an indication of sucking too much out.
Add in the fact the truck literally flamed as the truck was rolling at a walking pace.. makes me question...
Additionally, CC saying TrueRC batts are the cause.. Wouldn't there be issues with the Motor or performance beofre the whole damn thing torches?

I've had 3 MM's go up in flames... 1 was due to a failed rotor - The others were the same setup I had previously used.

I concluded it was the "weak" batteries - When I added extra capacitors to the MM I have since not had an issue. I believe the issue is that under large amp draw the batteries voltage dip - this creates "voltage ripple" into the ESC that without suffecient buffer i.e. capacitors the ESC can't take it and basically self destructs.

I would guess this is what happened to you...

The damage was done probably when you pulled the trigger from stationary as this is when the amp draw hits...

ps that is the lay persons explanations - search on voltage ripple

Sounds more logical than the rest of the explanations.. The weak battery blame though.. Bothers me a bit. Guess I'll just chalk it up as a "once Bitten twice shy" event and move forward.

Interesting is now there a need to add caps to a MMM like we all used to do to the MM...

Maxamps are no better than the true rc cells, and neither is going to keep up with a a setup geared for 55 mph...

Sounds like you over amped the esc. Amp draw of the 1.5d on 6s with that gearing is going to be high. You may have a faulty fet, and that is what smoked. I would say that it would be better to gear the 4s setup up to reach higher speeds.

They won't rate it.. Say it's bullet proof.. and can handle more than you can throw at it...
Well..it IS bullet proof as it will never see anything though... as for handling anything you throw at is.. as long they aren't CHEAP batteries which no one can really determine.. unless that is determined solely by how much you spend on them(MaxAmps), don't change any of the settings in Castle Link, or use the BEC... :)
By the time this crap is even remotely headed to a resolution.. Winter will be in the air and it will be spring before the revo can come out and play again.