MMM Explodes into FLAMES!

[shaunjohnson]

and how big are thoes tyres? what gearing?
6s!!!???
sounds like you did push it too hard after all to me :(

[suicideneil]

I've had my chocolate sponge cake & custard, Im all better now (sorry about that, it was a long day at work and yes I do need to get laid thanks, anyone got a spare 16-25 y/o daughter I can borrow?).

When using larger diameter tires, especially heavy ones (relatively speaking), gearing down cures most ills; 40-45mph is a nice zone to be in for any given combo/setup, controllable speed and lots of power still given a decent electrical setup (good lipos and torquey motor). Anything faster than that and gping lightweight is important to reduce the load on the esc and batts, since tall gearing will pull alot of current, so the less strain the better.

Originally Posted by suicideneil

I've had my chocolate sponge cake & custard, Im all better now (sorry about that, it was a long day at work and yes I do need to get laid thanks, anyone got a spare 16-25 y/o daughter I can borrow?).

When using larger diameter tires, especially heavy ones (relatively speaking), gearing down cures most ills; 40-45mph is a nice zone to be in for any given combo/setup, controllable speed and lots of power still given a decent electrical setup (good lipos and torquey motor). Anything faster than that and gping lightweight is important to reduce the load on the esc and batts, since tall gearing will pull alot of current, so the less strain the better.

16 huh, you must have different laws in the UK. that would get me a free trip to jail

[shaunjohnson]

Originally Posted by e-rev project

16 huh, you must have different laws in the UK. that would get me a free trip to jail

hence why they invented 'get out of jail free' cards

[muted]

If it wasn't for the pictures of the melted monster, I probably wouldn't have believed it. Until today when mine burst into flames just after arming!

[jpoprock]

Muted: WTF???? Whu happon? Just after arming? That's wild!

You know what guys... I remembered the other day that this last run where my MMM melted was NOT the first time I ran my Moabs. I ran them about a week before, on fine gravel, and ran it hard. It was sliding and skidding like mad. It was insane fun! I ran it much harder that time, then I did when it smoked. When it smoked, it was like half speed driving.

I still haven't looked in the tranny area, but I suppose there could some gravel lodged in there somewhere, causing binding maybe. I need to look still. But my MMM is off to Castle, so we'll see.

[shaunjohnson]

this is only what i have heard...i may have got it wrong but i'm sure one of the pro's will correct me...


i think your issue and muted's issue are related.

it isnt always the amp draw, it can sometimes be the braking that kills them.
when you use the breaks, power flows back through the MMM and into the battery, if the battery isnt a high enough AMP rating (say 80A cont or something rather than the recomended 150A) then the resistance causes the voltage inside the ESC to rize, in some cases this can destroy or damage the phase caps.
now when the phase caps die they seem to go quietly, like just before you finish off a battery pack and put it away.
the blown up caps wont always prevent it from running straight away, and the ESC can soldier on for a bit longer.

but next time you turn it on and it's armed itself, it trys to use hte caps and...oh no they arnt there...so BOOM
these problems seem to happen more often on 6s operation...because the voltage is already high so it is already getting closer to the 40v MAX braking voltage rating.

i belive the problem you guys both have might be related with the caps, jpoprock might have used the car a bit longer after hte caps went pop and as soon as the ESC needed the caps again...well....
but as for muted, i think his caps may have gone just before he brought her in for the day at the end of the pack or something, hence when he turned it on next time and hte caps were needed...fire

hope one of the more experienced guys can clear up weather i am right or weather i completely fecked up
sorry for the loss.
shaun

[muted]

Yea it was crazy. I just got it out of the car, connected the battery, turned it on, it made all the right noises, then when I pushed the throttle on, it cogged a bit, then started smoking, then snap crackle pop! A little fire shot out of it.
I disconnected the battery before even thinking about it, and my mate just started ripping the wires out of it. The wires ended up about 10 feet away!

Just turning it on, then 5 secs later turning it off, it shouldn't of even started to warm the battery, but even after 5 minutes, when we came back after searching for the wires, it was warm to the touch. Must of drawn some serious amperage!

When I took it out for a run the day before it ran perfectly, then the last bit before I went home it was cogging something severely. Took it home expecting to find some rocks caught in the transmission but nothing at all.

[Sammus]

could be a motor problem. if something bad happens in the motor (ie a coil shorting) it will cause cogging and massive current draw like that.

[fastbaja5b]

Originally Posted by muted

Yea it was crazy. I just got it out of the car, connected the battery, turned it on, it made all the right noises, then when I pushed the throttle on, it cogged a bit, then started smoking, then snap crackle pop! A little fire shot out of it.
I disconnected the battery before even thinking about it, and my mate just started ripping the wires out of it. The wires ended up about 10 feet away!

Just turning it on, then 5 secs later turning it off, it shouldn't of even started to warm the battery, but even after 5 minutes, when we came back after searching for the wires, it was warm to the touch. Must of drawn some serious amperage!

When I took it out for a run the day before it ran perfectly, then the last bit before I went home it was cogging something severely. Took it home expecting to find some rocks caught in the transmission but nothing at all.

Was this on 4 or 6s lipo?

[suicideneil]

Originally Posted by muted

When I took it out for a run the day before it ran perfectly, then the last bit before I went home it was cogging something severely.

You cooked and de-magged your motor, then the next time you used it > cooked esc.

Unless the motor wasnt hot after the last run, temps?

[shaunjohnson]

did you even read what i wrote?

[93firebird]

Originally Posted by Sammus

AFAIK V3 ESCs have the battery wires soldered directly to the board, not sockets on the ESC on the battery side.

Not all of them did. some of the earlier ones still had the removable wires. As did my first v3 replacement.

[suicideneil]

Originally Posted by shaunjohnson

did you even read what i wrote?

Yes, you talk about blown caps due to over voltage, I talk about a dem-magged motor due to excessive heat, that then causes massive current draw trying to get the motor spinning; that much current will cook the fets.

Blown caps due to over voltage seems unlikely as:

A) Its a 25v esc, the caps are spec'd for 35v- I dont know where you're getting 40v from, but it aint happening. The voltage being put back into the batts as a result of regenerative braking is no more than a few mV, as proven by a nice eagletree graph someone did back along as a practicle test.

B) I dont need a B as my A was so great

The hot lipo packs would seem to support the 'massive current draw as a result of trying to turn over a dead motor theory'. Could be something else that is going pop though, but aparently castle (and HPI...) can access some sort of data recording chip inside the esc to do an autopsy....

[BrianG]

Originally Posted by suicideneil

...but aparently castle (and HPI...) can access some sort of data recording chip inside the esc to do an autopsy....

lol, an ESC "black box" (like they have in airplanes).