The issue has not come back. Meanwhile I did replace the 12 V battery. As someone suggested, I had the shop do a load test on it: It could not complete the test (the last reading was down to about 7.5V before it could no longer even power the test instrumentation itself).

It is true that in both cases I was using a lot of battery assist deliberately. Since then I have avoided riding the pack that hard for any reason.

Bottom line, I'm guessing the combination of low SoC, high EV assist, cool temperatures, and weak 12V battery was deadly to the computer.

I stand by my assertion that this is a foreseeable use-case scenario, and a well-engineered design should be able to survive such a condition without putting the user's life at risk.

I'll file a report at the NHTSA safercars.gov site just to be thorough, but for now I'll consider this more or less "resolved".

 

Good idea. Hope you get down to the cause! I would ask for a replacement. Honda should be able to pin point, what is causing this failure. A good tech. should anyway.H