EV Defeated in Cold Weather???

We've had a few days of pretty cold weather, close to zero F. a day or two ago, and I think it was around 10 degrees yesterday morning. My garage is not heated.

Halfway along my morning commute the battery has generally been at 6 bars for a few blocks, the ICE is warm, but lack of a 10-second stop leaves me still in S3. So I use EV for 2 or 3 blocks to draw it down and create headroom, then let the ICE start again.

But yesterday morning EV would not engage. I tried periodically for the rest of the trip, but no go. Always the three beeps. So the switch was functioning, but the car did not want to go electric. Feathering the pedal would not get into golf-cart mode either. -- A bit later in the day, it had warmed up a little, it still would not go into EV. Feathering the pedal would get it to go electric for about one second, but immediately the ICE started again.

The SOC went up to 7 bars (green). Finally, a bit later, it was willing to go into EV mode.

Will a cold battery prevent EV mode? Does anybody know? It's warmer today, and not forecast to get cold again until the weekend. I was hoping that my phenominally bad mpg last winter was at least partly due to the newness of the car. I got it smak-dab in the middle of winter, in our coldest weather, and now I'm concerned that that low mpg might have had more to do with the characteristics of a cold battery, and the HSD's refusal to go electric, than because of the operation of the cabin heater.

I was counting on the EV switch to help me counteract the cold-weather mileage hit, because up until now I've been able to go into EV mode even when the heater was on, and when the car would not go into S4 because I don't have the long stop unless I happen to hit a red light. I believe that a nearly-full battery reduces efficiency. Last winter my battery was always at 6 or 7 bars, because the car so seldom got to S4 operation. I can mimic S4 operatiion with the EV switch, but if the cold weather is going to defeat the EV switch, I won't be able to. This is not good.

 

Jim: Thanks for the link to Evan's post; and Evan, thanks for that. (I'm not in the habit of reading the MPG forum.)

Well, all I can say is, it's time for Toyota to start using capacitors, to eliminate or attenuate the effect of cold on the battery. Just as the battery provides added torque when the ICE would not have enough, capacitors could (?) provide current when the battery is too cold. And just as the ICE recharges the battery when battery power is not needed, the battery could slowly recharge the capacitors, even in cold weather.

My problem is that my commute is so short that I'm nearly there before the cabin is warm, so the battery never does get warm.

:x :x :x :x :x

 

Problems with an EV: The nuisance of having to charge it; my garage does not match my apartment, which is no problem for the electricity used by the light and the door opener, and even the air compressor, but would be a real issue if I was charging a car; I have room to park only one car, and for longer trips an EV does not have the range (with today's technology); nobody is currently selling EVs; there is no place to charge an EV except at home.

Problems with the Prius: The heater is too small; in winter it won't go into electric mode much, and so it is less "cool" than it is in summer; in winter it probably only gets 50% better mileage than a conventional car, instead of 100% better.

The Prius is definitely a success. It's got a ways to go yet. But I think we all agree that the Prius is an intermediate solution, a work in progress, not the final answer to everything ™. We just have to keep letting Toyota know where it falls short. They won't answer us. But I bet they've got their ear to the ground as they design future models.

 

In the U.S. model there is no message on the MFD when EV fails to engage. Just the three beeps.

Maximum speed for EV mode is between 33 and 34 mph. (It will generally run in electric mode up to 42 mph. But if electric is forced with the EV switch, it will cut out at the lower speed.)

Thanks for the info about the defroster. It's definitely more reluctant to shut off the ICE when the heater is on, but sometimes it will. I was not aware that the defroster would definitely prevent EV mode.