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

[TexasSP]

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

[JaySki]

Originally Posted by TexasSP

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.

[bruce750i]

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

[JaySki]

Originally Posted by bruce750i

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

21/58 and 16/58 respectively.

[jhautz]

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

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

[JaySki]

Originally Posted by jhautz

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

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

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.

[TexasSP]

Originally Posted by JaySki

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.

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.

[JaySki]

Originally Posted by TexasSP

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.

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?

[lincpimp]

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.

[JaySki]

Originally Posted by lincpimp

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.

Then the dang thing shouldn't be rated for 6S and claim to handle "more than you can throw at it" Give me something to go by and to work WITHIN.

I agree with gearing for a bit more speed on 4S, but again, you start to deal with heat issues.. and running 55 more than a pass or two is .. for the most part.. Boring. It's not like you can really drive it around at 55mph. We can;t even really keep tires on them over 45ish without taping, gluing, re gluing, re gluing, etc...

As I said. My attempts with 6S were merely for a run or two geared up as far as I thought would be safe to keep the heat off the ESC. Even then.. I never opened up the throttle. You can't.. #1, torque is insane and won't keep rubber down. 2. Ya run out of space fast if you try and feather the throttle. 3. even if you have the space.. the radio distance will likely limit you.. or your eyes will.