“Unfortunately your file was cut by Toyota Canada at this time”

With PP, anything below -10C, the engine will start automatically if the heat is on. And even if the EV can operate without turning on the heat, the range is reduced by half compared to the warm season. I have not had a day PP did not start because of cold, but the manual warns that at about -30C, the hybrid system becomes unavailable, meaning the car would not start. I am sure BEV with better thermal management will have no problem starting and running the car very cold. I am curious to find out how the cold temperature affects the EV range, especially in short daily commuting.

 

I can live with a vehicle using a lot of fuel on cold days, but simply not starting below -30 is a major drawback. I wonder if this actually happens, or if it is more like when you get to -40 you might have problems.

I have started my gen2 and gen3 prius a handful times where the dash computer read -36, -32, or -34 degrees celcius and I remember these instances in particular due to how extreme the weather was. In all of these cases I did not have the car plugged into the block heater overnight and it coped with it just fine, except for a nasty squealing of the cabin fan in my gen 2 for a few seconds, and the touch screen being slow to react.

But outside of that starting my car after it has been sitting in the -20c to -29c range is so common for me it is not even memorable.

 

Although Toyota, Chevy and others figure you don’t need to drive at cold temperatures, perhaps Hondas original solution is still prudent.

have an aux 12v starter.

It’s too bad the big companies don’t care about cold weather.

Even Tesla will terminate your warranty if your car sits below a certain temp more than a certain time period without being plugged in.

There are a variety of scenarios that can’t be met.

Lots of bad design decisions being made these days

 

The warning says "below approximately -22F (-30F)", but the actual mechanism for shutting down the car is likely linked to the temperature sensor of the traction battery, not of the cabin or outside temperature. Due to its thermal mass, the battery tends to keep the heat longer than cabin air. In my experience, the temperature measured at the casing of the traction battery is usually warmer than the cabin air which is warmer than the outside ambient temperature. Around where I live, the coldest temp rarely goes below -14F (-25C). We have had a historical record of colder days, but so far, I have not experienced it with my PP.

Then there is the chemistry difference between Gen2, Gen3 NiMH vs Gen4, PP Li-Ion. I don't know if a similar warning existed for Gen2 and Gen3? For that, does the regular Gen4 has a similar warning as PP? I don't know. But got me curious.

 

That warning is for the Prius Prime, which has a Li-ion battery. There is risk of damage to it when charged at below freezing. It has a heater, which is why it can be used down to -30C. The rest of the drive train just suffers from the usual performance reduction with extreme cold, it just can't go without the battery, and the system takes care to protect the battery.

The NiMH in your current and past hybrids has very good cold performance. When the large format patent expired, BASF announced the potential for improving NiMH. Maybe NiMH packs for EVs will happen for markets with extreme cold. Energy density and range will still be worse than Li-ion, though. There are also lithium chemistries that can handle cold better, and some research going on with internal heaters, but with increased cost.

The Li-ion and freezing issue is with charging. It will be at reduced performance, like all cold batteries, but there isn't that damage risk when discharging a Li-ion at freezing temps. So a Li-ion hybrid could start up, and run majority on the engine until the battery warms up. Which would be faster because of the smaller mass.

Honda's original solution was in case of battery failure. As a mild parallel hybrid, the car didn't need the hybrid system to move. A power-split hybrid like the Prius isn't going anywhere without a battery, even if the engine can be started.

Didn't it take some intervention to get an IMA hybrid to use the 12V starter? It wasn't something the car did automatically.

There are solutions for these cars in extreme cold. It just is an added cost, that reduces profits. Right now, the companies have more than enough customers outside those extreme cold areas. Not saying it's right, just not likely to change without outside intervention.

 

All non-AWD 4th gen Prius except base level are lithium Ion IIRC.

 

Owning a Volt I can definitely attest to a situation where the hybrid battery is locked out.

When I have had to park in temps below -25F for work and couldn’t plug in the car engine would instantly start, the energy meter would be blank a bit, using dash daq the car will draw small amounts of energy from the battery but regen is off and acceleration lags a lot as the engine revs up for series operations.

Chevy already had a frozen battery mode, unfortunate they didn’t include an aux starter.

I have an old insight it will crank the 12 volt battery when it’s below -20F or so

It will also crank off the 12 volt if the big battery is dead.

Takes a good 20 seconds of holding the key in start when the large battery is dead.

 

Well, I just checked the 2021 Prius Owner's Manual. The same warning about the "extremely cold environment" exists in the Owner's Manual for the regular Gen4 Prius as well. However, looking at the 2015 regular Gen3 Prius (NiMH battery) and 2015 Pip (Li-Ion battery), I did not find the warning on "starting the hybrid system in an extremely cold environment". So, the warning is specific to the Gen4 Prius (including PP and Prius AWD). As I understand, Prius AWD is equipped with a NiMH battery, and so is the base ECO model regular Prius. Therefore, this warning is not specific to the Li-Ion traction battery nor to the wall-charging PHEV.

It may be another lawyer injected over-cautionary warning inserted into the manual to avoid possible litigation? Have there been any reports of Prius Prime or Gen4 not starting due to extreme cold? I have not seen one yet.

Toyota 2021 Prius Owner's Manual (OM47E09U)

View PDF

 

Again IIRC, there's a "base" level with Nimh, then the higher level Eco (which oddly strips the spare and rear wiper ) has the lith ion? Oh, but you do get more air pressure in the tires, lol.

 

I thought the ECO model was the "base" model with a NiMH battery... but you may be correct on this. I wasn't sure. In any case, the "extremely cold environment" warning applies to both NiMH-equipped and Li-Ion-equipped Gen4 Prius including Prius Prime PHEV, but not to the NiMH-equipped Gen3 Prius nor to the Li-Ion-equipped Gen3 Pip PHEV. So, the notion that the warning only applies to Li-Ion battery charging needs to be re-evaluated.

 

Think we're both kinda right. When you're trying to find out how the goal posts shifted over the model years, this site is great:

Auto-Brochures | Toyota Car PDF Sales Brochure/Catalog/Flyer/Info 4Runner 86 Avalon Camry Celica CH-R Corolla Corolla Cross Corolla iM Corona
Echo FJ Cruiser Highlander Land Cruiser Mark II Matrix Mirai MR2 Prius RAV4 Sequoia Sienna Solara Supra Tacoma Tundra Venza Yaris

I only checked 2016 and 2019, suspect the restructure of the levels in 2019, the mid-gen facelift year.

US 2016 Prius:





US 2019 Prius:

 

The true base L isn't available at retail in the US anymore. The L Eco is our base, and has been for most of the gen4's run. The L, along with the plain white paint, was likely always available for fleet sales. It was briefly available at retail. IIRC, as a response to the Ioniq's arrival. I think the equipment(no rear wiper) between the two trims was mostly the same. Aside from the battery. On the L, it was for lower cost. For the L Eco, the lower curb weight meant more favorable conditions for official efficiency testing.

edit: For those familiar with the one number system for Prius trims, the L is equal to the One, which only went on sale to the general public with the arrival of the Insight2.

I'd expect similar behavior from the Prius. Putting in to a 'frozen' Li-ion leads to lithium plating at one of the electrodes. Aside form the general performance reduction from the temperature, pulling energy out isn't a problem. Doing so will actually help it warm up. The cars avoid charging the packs, and the packs are too cold to give much help, let alone support EV mode. So you end up running the engine more.

The frozen battery mode is what you described above?

Did you actually have need for an aux starter? I don't see why a Volt or Prius would need one. Assuming no other problems, there would be enough charge in the battery to spin up the engine. If there is another issue, it is something major enough that driving the car isn't a good idea.

If an aux starter was needed, a true starter 12V battery would be needed, and the starter itself would likely need to be more powerful than would an engine of that size would normally have. On a Prius, it will also be spinning M/G1. Which is two to three times the power rating of the motor on the Insight.

Okay. Poster at another forum mentioned having to do something first. But the traction battery was actually dead, and he needed to get the car into a non-hybrid mode.

With the early IMAs, Honda was, um, aggressive with the battery management. NiMH has one of the highest self discharge rates for a chemistry. That combined with the car letting the SOC getting low, could add up to the pack not having enough energy to start. NiMH might be better at working in extreme cold than lead-acid though.

For the Li-ion cars, the warning is more about charging the battery than starting the car. Regular operation of these hybrids means charging the battery during the trip.

This is likely. Simpler to write up a warning for worse case to a specific equipment set, and paste it to similar models, than go into all the exceptions.