Burning smell on high current regen braking

Hi everyone. This morning I noticed a strong burning odor, like burning wax. It only seems to occur on high current regen events (eg coming off the freeway). It also happens to be raining, although I'm not sure if that's part of the issue or just a coincidence. Any ideas?

 

I'll definitely take a look if I can't rule out the problem in some other way. Someone in another thread mentioned another interesting idea, a plastic bag stuck to the exhaust pipe, which seems a lot more likely in the rain. In retrospect, that would explain why it only smelled on the freeway and didn't smell when I braked to a stop going downhill at 50mph. The peak current might be higher, but if there were connectin issues it should still show up if the current were say, 50% of that. I also think that the display would do all sorts of odd things/throw codes if there was that much arcing (to the point where we could smell it) going on with the pack connectors.

 

The battery SOC varied. After my girlfriend drove the car home I looked underneath and sure enough there was a big clump of shrink wrap.

Edit- The fun part is going to be trying to get the melted chunk of crap off of the cat/exhaust. Hopefully , brake/carb cleaner, acetone, and/or ammonia will work as per random google results.