MMM v3 up in flames!!!

[BrianG]

Quick electronics lesson:

Caps have two functions: To pass/block certain AC frequencies (like in audio crossovers, oscillator tank circuits, timing, etc) and storage (like filtering power supply output). ESCs are using the main low-ESR caps (Equivalent Series Resistance) in "storage mode".

All caps have a "resistance" and when you quickly charge/discharge a cap at high current (due to the motor), the resulting high charge/discharge currents ("ripple current") along with the caps resistance creates heat. Lower resistance means less heat.

Lower quality batteries will drop voltage under load more, causing the caps to charge/discharge deeper which increases the current flow (and heat) in the cap. But, even low-ESR caps have limits and if they have too much ripple current, they will overheat and not do their jobs. Component failure and circuit instability can result.

So, you can either add in a bunch of extra low-ESR caps to help compensate, or just use a better quality battery that drops less under load.

EDIT: All that and JRH answers the question in less than two lines.

[lutach]

I find it strange that only the Mamba Monster is having this problem. This might also have been the cause of the Schulze ESCs to go up in flames as well. I haven't heard this happening to any other brand of ESC (I might be wrong). There's got to be something else causing this problems. You can't just blame the batteries. I had my Schulze go up in flames, but with the same set up no other ESC has done that. Even though the Zippys might use lower grade lipos they are still better then NiXX, so will the Mamba Monster fail all the time because the NiXX can't supply enough current?

I'm just curious as I still haven't used my Mamba Monster, but I would like to know if something else is causing the problems.

[johnrobholmes]

I like your explanation better Brian :D More informative. If we really wanted to get into it, we could explain how switching frequency affects ripple current, along with wire lengths and battery quality. I don't have a silly scope to make those measurements with though. Easy way to explain it is that ESCs get hotter under partial throttle, and ESCs run cooler under full throttle.

I have seen plenty of mamba's and sidewinders go up in flames too. The only way to REALLy figure out what is going on would be to hook his setup onto a scope and run the rig under load.