GII EV Mode, temp < 15F, WTH was going on today?

Ok well I made the ~3 mile trip to Chipotle and back for lunch today and had some strange happenings with the EV button. Unfortunately I did not have my CAN sniffer plugged in.

So start the car all normal, and let it warm up the engine as I can't make it there on electric only today (takes about 6 bars to get there on EV only, only had 4). When I get to the stop light right before the plaza, usually the engine is warmed up, so I press the EV button and kill the engine as I glide to a stop. Today I pressed the button, I felt the engine die, then within a second or two, it came back on. I did not get the double beep of denial, it just came back to life by itself. At the light and stopped and within a second or two it shut of normally like a "normal" GII Prius. Pull into the plaza, leave the car on while I grab my food to prevent another warmup cycle and keep my sirius tuner recording so I can skip forwards/back . While cruising through the parking lot to get out, I usually keep it in EV just to be cool lol, so I had stopped at the stop sign to turn out, and before I press the gas the engine came on again for a split second then killed itself almost instantly. My SOC was around 5 or 6 bars at this point. Outside air temp was reading around 15F.

I remember this briefly happening earlier this year when it was negative farenheit temperatures, but I shrugged it off since I was still a n00b. Now knowing a bit more about the warmup cycles and stages and having spent numerous days inside logging and cataloging network traffic I am confused as to what was going on.

If the engine was too cold, or the SOC was too low, then I should have received the double beep of denial when the EV button was pressed or when the planets aligned in such a way to force it out of EV. I can confirm the button was working properly as it definately killed the engine when pressed, it just didnt remain killed. I never drive with climate control on (air set to max cool, ac off, fans off, defroster off, completely dead) and was the same today as when the engine was off, it was entirely silent.

Ideas as to what she was thinking today?!

 

The heater was not on. I do not drive with climate controls on as explained above. Just wear a jacket and it is ok.

Offtopic: Are you in Trinidad, the island?

 

Not currently but I am building my own. I use the EV button currently to shutdown the engine when gliding to a stop or to cruise about parking lots mostly. There are times when I can get to the shopping plaza on EV alone and end up with the same bars as I started with since it is downhill mostly. But the beginning stretch is uphill and then level, so it takes some bars, drops to 3 then regens back to 6 or 7 by the time I am there.

 

Could be. I wish I had my breaboard hooked up and was looking at the max hv current draw sensor, that would show if it was indeed being current limited by the cold. I wouldn't count 15F as really cold, but I know NiMH does.

However, I would have assumed the Prius would have beeped to deny EV access or beeped to get out of EV mode once the ECU determined it needed more current than the battery was allowed to give for the current temp.

We have another day or two of this sort of weather so I will try to collect more data.