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.
Daniel, See Evan's post Here From what I have read here I definitely think that there is a temp sensor on the battery that affects the HSD operation.
Yup, I'm almost positive that a cold battery functions poorly and thus Toyota built in safeguards to reduce/prevent it's use.
I've noted this in hot temps here in AZ summer as well - but probably due to full load A/C trying to run at the same time.
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
I do believe that there is 4 temp sensors in the physical battery pack as well as a temp sensor in the battery housing to measure the internal temp and send the data to the computer and the software in the computer probably has upper and lower operating limits. In the Classic you'll get the "turtle" if the HV battery is cold which mean it has less capacity till it gets warm. A really cold battery will probably force the ICE to run so that the battery gets some warm air into it to get the battery to a temp were the charging and discharging capabilities are in the "normal" range. That is probably one of the reasons that the ICE runs so much longer in the winter. The other is that i've noticed is the ICE cools very fast, you can loose 6 degrees C in a matter of 3-4 minutes and that was in weather of about freezing not minus 5. Just think if you had a Hemi what your mileage would be! The Prius is trying hard to be enviromentaly efficient as well so these are some of the tradeoffs. Next spring your mileage will be way up and the Hemi will still be the same.
I have not noticed any consistent reason yet. But with the cold snap the last few days, I noticed that the ICE would start immediately after pushing the power button.
<div class='quotetop'>QUOTE(drew\";p=\"60006)</div> I think the country and technology have 'been there, done that'...the concept is nice, but for the cost, space, resources used to produce, and small amount of money saved it's not worth it unless ALL your driving is short commutes. Otherwise you need a second vehicle. I know of very few people for whom that would be convenient. Also, the EV button isn't for commuting.
pure electric vehicles are not very efficient in really cold climates either. Take electric forklifts used in cold storage plants. They use the same battery technology as EV cars, large LA batterys and when in use they only make about 40% duration that the same battery in non-cold storage applications make. Most as an example are able to do about 1/2 a shift without changing over to another battery in a charging station, read this as swapped out the dead for a charged one, where as in normal warehousing applications the same truck battery combination will do a full shift. Batterys don't like cold weather, man made or mother nature. The efficiency drops right off and if you let a LA get low on charge when it's cold it'll freeze and possible damage the cell separators and the plates. When that happens you have to thaw it out completely and then recharge it. Any idea how long it takes to thaw out a battery that weights 4000 lbs, about a week at 50 degrees F. I'm not sure how much the battery in the EV1 weighed but it was a lot more than the one in a Prius. The EV1 was a partial success in California but I doubt it'd be in Fargo N.D. in the winter. Then there is the electricity bill to run the charger. If you ask Daniel I think he'll tell you the Prius is more than a partial success.
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.
I just put in the Coastal Tech EV switch yesterday. Haven't had a chance to do other than test it yet. In the knowledge base Evan posted the UK owner's manual instructions for the EV. Including: In the following conditions, the "EV" drive mode may not be turned on. In this case, the message appears on the multi-information display and a beep sounds. -The hybrid system gets hot. (after the vehicle is left in hot weather, after driving on the slopes or high speed driving etc.) -The hybrid system gets cold. (After the vehicle has long been left below 0oC (32oF).) -During gasoline engine warm up -The hybrid vehicle battery assembly charging level is 3 or lower. -The vehicle speed is about 45 km/h (28 mph) or over -The accelerator pedal is depressed strongly or on the slopes. -The defroster is in use So it could be either because of the cold, or because you were using the defroster.
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.
I've used my EV switch 2 days now. Interesting note: I don't get the '1 beep' engage notice if the MFD is already on the battery screen. Thus, when I try to set it, not knowing if the engine temp is up enough yet, I have no idea if it worked or not until I have passed a point I KNOW I must be in EV or when the engine kicks in. Maybe the beep is the screen switch and there isn't a specific audible notification when EV engages? I know the European cars have a dash light to tell them it is engaged.
