Battery sag + full throttle = burnt smell?

[jdss13]

I've been doing some mods on my rig which added some extra weight. Yesterday I was testing the rig and tried full throttle against the wall but the motor didn't have enough torque so nothing happened. I immediately noticed a burnt smell but I'm not sure where it came from. Today I tested a new Lipo, again full throttle against a wall and got the wheels to spin, no apparent sag at all. Now I'm wondering where the burnt smell came from, I thought it was the motor but now that it appears that the problem was battery sag (btw it's the original nihm), I'm confused where the burnt smell came from. Would drawing too much amps from a bad battery cause your esc to burn? Or was the smell coming from the motor struggling to keep up with the lack of amps provided? I have no clue really

[QuesoDelDiablo]

First off, testing against a wall like that seems like a really bad idea. Like, a really really bad idea. I'd recommend not doing that ever again..

The smell was most likely the brushes in motor burning.

My guesstimate of what you've seen is that with your NiMH pack there wasn't enough amps available to get the comm spinning but you were still pushing a large quantity of power through the brushes which then started to burn because the amps had nowhere to go and turned into heat. And then when you did the same thing with the LiPo, it had more amps available so it was able to get the comm spinning and then not burn the brushes because the amps were flowing.

[jdss13]

That seems to make sense QuesoDelDiablo, I'll make sure never to stress test a rig like that again. Thanks!!