2020 Prius Prime and Extreme Cold...

Several of us noticed the increased tendency for 2021 PP to start the engine. My own comparison is between 2017 and 2021, but it is possible that 2020 PP might have behaved similarly to my current 2021 PP as you are stating on your 2020 model. I just did not drive the 2020 PP often enough to make any observation.

My suspicion was that Toyota tweaked something on later models to make the engine fire more often than the earlier model.Your observation strengthens that theory.

@john1701a confirmed that the traction battery heater continue to turn on periodically while his 2017 PP was kept plugged in with L2 EVSE. Now, I don't know if this behavior also have changed in the 2020 or later models.

 

It was -20°F outside our garage this morning. Here's what the battery-warmer and pre-conditioning did in response to that.

 

I feel vindicated!

My 2022 PP has a definite bias to running the ICE in cold ambient temperatures.


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The question then becomes…why?

It’s largely academic to me (I enjoy the SIGNIFICANT fuel savings vs my previous daily driver—2013 Xterra—but I’m not dedicated enough to wring out the last bit of efficiency every single time I drive) but I’m always interested in understanding how and why things work.

 

Good question indeed.

I believe Toyota changed things a bit for the 2019-2020 model year as well as for every newer Prime since... which perhaps coincides with the increase in the battery pack warranty from 8 years to 10 years. Last year, I had a nice chat with my contact at TCI and he was unable to confirm any of my observations.

Still, I suspect quite a few parameters were adjusted for the newer Primes which clearly affect the behavior at least on the colder end of the performance envelope. The difference in cold weather behavior is pretty obvious to me and because of this, I have continued taking snapshots of the pack's module health every six months for both cars and comparing them as they age.

By the way, Toyota sent a survey to me 1 month or two ago asking me what my EV usage pattern looked like. It was very focused on EV range, cold weather operation, use of the cabin heater vs heated seats, etc. I was pleasantly surprised by it. Did anyone else in Canada recall receiving a similar survey?

Cheers

ms

 

Since you have both 2018 and 2020, I want to ask you this question. Have you noticed any difference in the total EV range from a full charge between those two model years, during the non-cold season?

I ask this because my new 2021 PP was showing noticeable improvement on the EV range over my previous 2017 PP in warmer months. Again, the change might have been seen on the 2020 model which I also owned. But I did not drive the 2020 PP long and often enough to know the difference. Before the cold weather started, I was easily getting 35 miles of EV range from my 2021 PP. For the similar condition and the same route, it was very difficult for me to get 35 miles of EV range from my 2017 PP. I have been checking the kWh from the wall to see if the kWh of battery used by EV mode has changed. There is a slightly more kWh from the wall for the 2021 PP compared to the 2017 PP, but the difference is not statistically significant since each full charge amount varies naturally.

 

I'm down in New York (from New Hampshire) for a few weeks and I'm noticing that with the even slightly warmer temps and having the car in an unheated, but not as cold as outside) garage, it definitely seems to be staying in EV mode on startup more often.

I'm wondering if it's not just ambient air temperature, but how cold the battery pack gets overnight up in NH that really impacts how much the 2021 PP will use EV mode. Even up in NH when it's colder, if I use the car a second time, after it's had a chance to warm up (and especially if it has been in the sun), it definites stays in EV more--guessing the battery, not just engine, is at a warmer temp.

 

Being able to get into EV may very well be associated with the battery temperature. One thing I am starting to notice on very cold days is if the PP is charged over night, it goes into EV mode more readily the following morning. Although I plug in when I arrive in the evening, the green charge light is on in the morning. I assume because the traction battery is being heated.


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As far as actual range and measured SoC goes, there no significant difference between these two.

However, the projected/estimated ranges do appear to differ.

For example, during the peak of the summer months the 2018 will easily estimate 63+ Kms of range often maxing out at 71-73 Kms.
The 2020 in the other hand never estimates that high. Almost appears the 2018 is more optimistic when guessing the remaining range on a full charge (83-84%).

Cheers

ms

 

Oh yes, another point I would like to make regarding the use of the block heater in very cold temps.

- The general idea with block heater use is that it is there to benefit the gasoline engine IF it needs to start. In other words, keeping the engine oil "warm" means reduced viscosity and greater lubricity on startup, which also reduces engine wear.

- However.... using the block heater in the Prime appears to offer an additional benefit as far as keeping the vehicle in EV during cold temps and when the battery heater also did its part.
From my measurements, using the block heater also warms up the MG1 & MG2 (duh!!!) which if used as inputs - as I think it does - may have an impact on whether the gas engine needs to start at all.

What I am trying to say is that during very cold days, I recommend that in addition to keeping the car plugged in to the L2, you also try using the block heater if you got one installed. This may help keep the car in EV for you as it does for me.

cheers

ms

 

I agree that anything the owner can think of to help keep the traction pack warmer in extreme cold temps will also help extend the life of the traction pack. Of course, if the car is left outside all day away from home and not plugged in, 8 or so hours of cold soak seeping into the traction pack compartment, that in my experience is going to bring the battery temps way down again. I've read other members might think it takes a lost longer for cold to soak the traction pack than what I've seen.
Being in a heated garage during the day like MSantos Prime is fairly unusual and I'd think would change the Prime cold weather behavior extensively. And although it's a Big variable, it's still only one of the variables in Primes programming that change as temps drop below freezing.
I've added an electric heater inside the Prime cabin while charging and for 20 minutes preconditioning in extreme cold and was really surprised that although the cabin was warm as toast the traction pack battery temps were not much higher ( way back there under the cargo area floor ) than they were without the heater running.
Still, I hope I'll be able to tweak the extra heating to get more heat way back there and around the battery to raise the battery temps a little more.

oh yeah, while looking up parts today and commenting in another thread about the price of Prime traction packs, I found 3 different part #'s for Prime traction packs. Two were from amayama and were for Prius PHV models with no guaranteed fitment for US Primes, and US Prime model years 17-18 have a different part # than Prime model years 19-21. The 17-18 traction pack part # was the same for the US Prime and one of the two PHV traction pack model #'s at amayama. So, it looks like the evidence of changes to the 2019 Prime is starting to add up.

 

Toyota is a master of continuous improvement... most if which is subtle and goes unnoticed.

 

I had two mornings in a row at -17C. This morning I only had the block heater plugged in the previous evening any I had no EV on my way to work this morning.

Yesterday morning, it occasionally went into EV. The previous evening the charge cord was plugged in.

This observation is aligned with the data presented above by John and that the charging must also be heating the traction battery if the option is selected, as it is on my 2022 PP.


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Mine is a 2022 prius prime, but I have noticed a couple times now even when in EV mode, the gas engine coming on & providing power. It's not EXTREME cold when this happens. Happened this morning at 24 deg F. Also when driving home the other day with snow coming down & similar temperatures. Why is it doing that? Any ideas?

 

I have a 2021 and it behaves similarly. Some posters with experience with earlier and newer versions have suggested/speculated changes in the battery management system have been made to engage the gas engine more frequently than before in temperatures a bit above previous model years. My totally amateur guess is it has something to do with keeping the battery warm at higher ambient temperatures than the earlier model years.

 

If you're using the heater, try turning down the heater temp. The ICE fires for odd reason (sometimes) with all Prius Primes.

 

If you ever see the green light staying ON where you plugin the EVSE and none of the 3 blue lights blinking on the dash, it's a good guess that the tiny traction pack heaters under the battery are working to keep the battery above freezing. I've only seen that once or twice this winter in below single digit/F temps for the first time.

DrPrius is currently showing the 3 battery temps in the mid to high 40/F ... I'd be happier reporting what techstream shows for the 5 traction pack banks, and a whole slue of other things too.

 

Very interesting on your consumption. Mine is a 22 and since I got it in November on board computer is saying just under 18kw/100kms. I have just under 10,000kms on it. Wonder if it’s just the winter that is making it so much worse or just needs to break in a bit more.

 

Sorry for the double message. However on you 2020 you said a trickle charger is on your block heater cord? I have tried to find info on my block heater and the sticker on it says is 1200watts which is the highest I’ve ever seen for a block heater and considering how small the engine is I thought 1200watts was rather odd