Worried sick about coming of winter

No need to worry. Just start the car and press the HV/EV to start the engine. It will warm the battery. My car was in EV mode after sitting out all night at 25 degrees Fahrenheit last weekend and the engine started automatically. The battery must have been cold as I had 95% charge. Then after a few minutes at 60 mph it went back to EV. Car is smart and will protect the battery.

 

At -40C (which is -40F), you probably do not want car plugged in anyway. I have read/heard that charging Li battery at extreme low temperature can cause damage. I don't get to see -40F (which is -40C) in our neck of woods. Our coldest winter temp is more like -20F (which is about -30C). For two winters now, I have parked my car outside, either plugged in or not plugged in (whole month of Feb), with no problem. Even with plugged in, when the temp is that low, the car will start ICE immediately. You can drive off with ICE on then it will switch to EV when battery warms up.

 

i'm worried too, but for me, not my car.

 

Tesla vehicles are designed to, if necessary, heat the battery pack prior to charging. I would expect most other cars with Li battery packs do the same. This, no damage will occur from plugging in a car when it is cold out.

 

because li-on does not perform as well as nimh in the cold, toyota stuck with nimh for the new awd prius

 

Heating batteries is rather consuming, so if left unplugged I imagine in extreme cold the battery depletes in just few days; after that it remains cold and loses a big chunk of capacity untill warmed back. I doubt it has catastrophic effect, but probably reduces longevity somewhat if repeated often.

 

Yes, that is also true for PRIME. However, there is an operator option to turn off the "Traction Battery Heater" function. I don't know how the car behaves if it is turned off and someone try to charge the battery in extreme cold.

 

Interesting!
I wonder why that is a user facing option?

Even if off, I would be shocked if Toyota allowed charging at a rate that would damage the battery.

 

I sure hope so. But I am not going to test that on my car. LOL

I have never experienced this situation, nor have I ever read here in PC who has reported this. But Toyota does warn about PRIME not being able to start in extreme cold below -22F (or -30C).

 

If you're planning on starting in hybrid mode, look into block heater?

 

OP said "the electricity outlet is too far away to allow me to keep car plugged during all night".

 

I have never kept fully charged car very long. But for example, during winter, if I charge over night and I don't drive the car next day for some reason, I don't think I have ever seen any loss of charge as far as SOC % or GOM EV miles on the dash goes. Also, as I said, I did not charge my PRIME whole month of Feb when it was the coldest in my area. I did this, because the car would start ICE anyway, and I needed ICE to heat the cabin most of the time. Plus in my area, electricity cost more than gas to drive PRIME on EV. After doing this, I have not noticed any ill effect on the battery capacity or EV range whatsoever. But that's after only two years of ownership. Any long term effect for longevity of the battery is not known.

 

It sounds like a lot of people are confused in this thread. The Prime has a battery heater, but as far as we know it only runs when the car is plugged in. The heater runs on 12V, so it could run any time, but my understanding is that it does not. It's not like Tesla where it will heat the battery with stored energy.

Lithium ion batteries will be damaged if they are charged too quickly when they are below freezing. But they can be charged slowly. The car will either wait for the battery heater to work, or charge more slowly, if the battery is frozen. It will not damage the battery to plug in the car, and it should only help since the battery heater can run.

While driving, even HV mode usually seems to discharge and charge the battery a little bit, because of the way the transmission works. The car can control the transmission so that all of the energy comes from the engine with zero charge or discharge current, but I'm not sure if that works for all driving scenarios. I'm not going to let my battery freeze to find out. Even if the engine is going to run anyway, I think it's better to plug in so the battery can stay warm, so that it can work more effectively.

Toyota must have designed the car to work if it's parked overnight in a cold place with no ability to charge. And the standard Prius uses a lithium battery, so it must also be able to handle the cold. Does it have any kind of battery heater?

I wonder if it would work to set the charge schedule so it doesn't charge, but plug in so that the battery heater can run if needed? That might require an experiment to test if it works.

The owner's manual has a couple notes about charging at low temperatures.

 

A couple things that will help:
The car doesn't care about wind chill, only air temperature. For example the lowest temperature recorded in Montreal is -37.8C, and it's usually warmer than that. For example the 99.6% design temperature is -26.7C, or in other words, on average, 99.6% of the year it's warmer than that (all but 35 hours per year). It's not too unusual for the wind chill to be -40 or lower, but inanimate objects are not affected by wind chill. Wind will make things cool off faster, but an object will rarely be able to get colder than the ambient temperature (it's possible by radiation on a clear night, but not really relevant here). Maybe you're in a colder part of Quebec than Montreal, but I'm just pointing out it might not be as bad as you think.

Also, the battery has a lot of mass, and it takes a while to heat up or cool down. It will heat up as you drive it and during the day, and it will slowly cool off at night. If you drive it everyday, the battery might still be 10 degrees or more above the ambient temperature the next morning.

A block heater would help the engine run more efficiently and get heat blowing sooner. You could run a block heater and the charger on the same circuit if you limit charging to 8A (a setting in the menu). A typical block heater is 400W, and it's not good to exceed around 1440W (12A or 80%) on a typical 15A circuit. My understanding is that a lot of parking lots have block heater plugs, is that still a thing? Are you allowed to plug an EV charger into one of those plugs?

 

With the block heater, you definitely do not want the cord to be capable of dangling to the ground, cus sooner or later you WILL forget to unplug. If you're bring it out through the front grill (watch out for grill shutters on 4th gen), secure it well, at two points close together, with zip ties. Also, use an extension cord that'll pull straight out, and without too much effort. And anchor that extension cord to something solid: I loop ours around a barbecue leg. That's pretty much the sole use for that barbecue, and it works excellent.

Those are just for block heaters as far as I know. If I'm not mistaken they cycle on/off alternate half hours. I noticed them when we were up in Williams Lake in the interior, the spring after we got our 2010. I got some puzzled looks, plugging in that time of year...

I just replaced ours, after about 9 years pretty heavy use, it shorted out, just at the connection to the heater element. DIY'd the replacement, a little difficult, mainly the struggle to get to the spot, and get all the existing cables and brackets out of the way enough:

Block heater failed | PriusChat

 

The charger would still work if it cycled on and off. Would the parking lot owner complain if you plugged in a charger? Would the larger load trip the circuit breaker?

Also, do you notice any improvement in efficiency using a block heater? I put one in my Toyota 4runner. I set it to run for about 4 hours in the mornings, and the change in fuel used was not even measurable compared to the amount of electricity used. And the faster warm-up to defrost the windshield was also barely noticeable. It has a V8 engine, so it uses an immersion heater (installing it was terrible). Maybe the engine is just too big and loses heat too quickly for a 400W heater to make much difference.