In cold temps, ICE turns on at the begining of a trip when I have plenty EV. Why?

It was probably around 25 mph. And most likely never going over about 1/3 of the HSI bar.

 

Giora, with the European model my experience so far is that engaging EV City is enough to prevent any problems of turning on the ICE unless you really push it into the power zone. The only other time I did get caught out was going down a hill too fast and braking within a couple of hundred yards of my home - couldn't work out why the ICE came on until I realised I had left fully charged, so there was no headroom for the regen, and the ICE came on to waste it.

 

In the post you are referring to I was speaking about ICE triggering due to demand for cabin heating. EV city will not prevent this, on the contrary, demand for cabin heat will cancel EV city (and unlike regular EV mode it will not resume automatically).

 

Ah, I thought you meant heating the battery, as per the posts above you. No, agreed, EV City makes no difference when heating the cabin, and I also find it odd that EV City doesn't resume automatically.

But my experience is that if the fan is off, the heating system is off, so that's not what is kicking the ICE on for the OP.

 

what happened to jimbo?

 

Good question, we are talking to ourselves again.

 

good thing we have us!

 

john1701a: I tried your timer theory, I set timer to finish a 8:00 am , Drove to work going 35 MPH, Engine came on dash board temp: 34 degrees.

 

i think there is a thread on this from last year. i don't think any conclusions were reached. seems like ymmv.

 

more like yevmv

 

35° here in the Finger Lakes today... Got in my PiP to drive across town to a doctors appointment. All proper things were turned off! Auto on the climate control, is off, fans are off, temperature set to lo, lights are off, windshield wipers are off. Only thing on was the car and my seat heater set to low (I like a warm tush...). Ice was run just a couple days ago and the car has only 15 or so miles on it since it ran. Pushed the on icon and the system came up. Drove 300' and the Ice fires up! I pulled over and shut down. Grrrr........! Started up again and it was fine on EV for the rest of the 1.2 mile trip. I do not know!

I do wish Toyota would explain why the thing appears to have a mind of its own. Nothing seems to work perfectly to keep the ICE from firing when it is cold out. That said I have driven when the temperature was under 10°F and not had the ICE come on.

 

One of the triggers is regen potential based on speed.
If the battery can only take 95% charge at 32 deg- and you're currently at 93% SOC and the PIP is traveling at 25 mph- there is a regen potential to overcharge the HV batt if you brake hard- so the PIP starts the ICE to "burn off" some batt power in case you do actually need to brake hard.

 

That has been my experience. It has been the stop a few blocks down the street when my ICE starts in the winter. When the charge is burned off enough to hold the regen this no longer happens.

 

I'm still of the thought process to always let the car finish whatever engine cycle it is on before shutting it down. (in other words, I must see a lit up EV light before I shut down)

 

You may be right, but to do that I would have had to sit and let the car idle for 5 minutes or so when I got to where I was going.... When it does that and I'm on my way to my son's house (8 miles), I will just let it run. This is the one thing that really irritates me about the PiP! If Toyota would state that there is an absolute reason why the car does this and a way to work around it starting randomly just because it is below 70°F I would like that. I really don't like getting 15 or so mpg out of a car like this just so the ICE can warm up! BTW, this is not because of braking. It doesn't happen when I am braking, it happens for no particular reason just when I am steadily going down the street using a modest amount of electric. If braking is the reason Toyota should just have the regular brakes come on instead of wasting gasoline!

 

Totally agree with your last sentence.

It's so weird that it's starting up. Have yet to have mine come on where I didn't know why. And I've had plenty of sub-50 temps.

 

I agree, it's not regen/braking. In my case I found by driving down the side streets at no more than 25 MPH ICE doesn't come on. I drove down theses side streets all last winter and only when the EV miles reached the 124 mile limit did ICE come on.

 

​

A side note: if you use the climate control "Off" button, there seems to be no need to set the temp to 'Low." You can leave it where you want it when the heat is on, and just use the "off" and fan 'Up' buttons to switch it off and on. You also don't need to turn the fan off yourself - it goes to off when you turn the CC off.​

 

Would be nice for the PiP to show the reason on the display whenever the ICE engages. Something like "abrupt acceleration" or "aggressive acceleration" or "125 EV miles reached" or "cabin heater activated" etc...

I too am sometimes affected by the mystery ICE start-ups. It hasn't happened since last winter, probably because it has not been cold enough. But last winter, sometimes on my 1.5 mile morning commute it would. The circumstances seem to be only in sub 40˚F temperatures, about 0.1-0.3 miles from my house. It could happen when braking, coasting, or even very gently accelerating. It always happened on a gentle downslope when I was near full charge, but always when the estimated EV range was less than when I started the car from - I have to go up a small hill first when I leave my house. I always charge the PiP to full overnight, but complete the charge about 6-8 hours before I go out in the mornings, so these are sorta cold starts. But my car is always garaged, where it is never less 50˚ F, and never less than mid to low 20s outside for a couple hours during the coldest mornings before dawn when I take off for work.

If this happens again, I plan to do some below capacity charges to see what happens.

 

just remember the faster you go the more current is drawn from the battery

The way I figure......when there is current draw from the battery, there is a corresponding voltage drop, when this voltage drop reaches a critical level, the engine kicks in which is probably Toyota software programming. Battery voltage drops are more pronounced the colder the battery is thus that is why the engine kicks in at 40 or 35 or lower degrees.