Prime EV mode in very hot climates

Does your car actually say that it's to hot to use EV mode? Does the battery not charge enough in 100°F weather? I would say that the Prius Prime would handle that temp. The new lithium ion battery pack in my gen 4 is a lot more powerful than my gen 2 nickel metal hydride battery. I can drive in EV mode in 100°F weather in my gen 4.

 

I think that more than outside temp alone, it's important factor if the car is on the sun or not. Prime could come with cabin pre-cooling, battery is cooling with cabin air.

 

My Plug in Prius drives in EV when temperatures exceed 100 degrees. It is my understanding that battery degradation is greater if the battery is full and the car is parked in the sun when the temperature is high. For this reason, I would expect the Prime to use up its EV portion of the battery as soon as possible in hot weather. The default mode of my Plug in Prius always does that unless I operate it in such a way as to cause it to start the gas engine.

 

In that climate I would make generous use of the Remote A/C function. I have the base PiP so it's only available from my key fob. The Advanced PiPs have remote A/C available via their cell phone I believe. This will use up some EV but will save your battery especially when parked in the sun for a bit with EV left. But back to your question. Once in EV mode it will stay in EV mode unless it drops to about 15F which I assume that won't be a problem.

If you would like to know more about Remote A/C and how it can use house current instead of EV range, I can explain its function in a bit more detail.


Unsupervised!

 

because the prime has pure ev function, it will be much better than the lift back. but that doesn't mean there won't be limitations. i don't recall reading anything yet, and it may be too early for a specification like that to be revealed.
keep in mind, ambient air temp and battery temp may be two different things. toyota is more likely to reduce out put at battery temps exceeding certain parameters. but you will be able to find some of this info before purchasing, although, it may not be comprehensive enough for your satisfaction.
a lot of good engineering data come from users, not toyota.

 

The Prius has a much smaller battery pack than the PiP and Prime. For cooling, this means more surface area to the volume of the pack, and thus the ability to shed heat faster. The big advantage of the prismatic NiMH cells versus the standard cylindrical ones was that they shed heat faster. The Escape hybrid, and maybe the Honda ones had an A/C loop to cool the pack, where Toyota was fine with just a fan.

All we know about the Prime's battery cooling is that it doesn't use a liquid system like the Volt. The Energi's are air cooled, and will reduce EV use when the battery gets too hot. The specifics on the Prime battery and cooling aren't out yet though. Newer chemistry could be more tolerable of heat, and there could be a supplemental cooling loop off the A/C for the battery. We just don't know at this point.

As for the OP's PiP, are you able to monitor the battery's temperature? How cold do you have the A/C? Check to make sure that the battery vent isn't blocked or clogged. Try to listen for that fan. You might want to consider having the battery and it's cooling system checked out.

 

That type of information on operation hasn't been release yet.

I can tell you that the Ford Energi series, which also use air cooling like the Prime, have an upper battery temp threshold of 113f when it will do the same thing as you described with your G3 and only drive in regular hybrid mode. NOTE: this is the pack temp not ambient outside temps. Level II charging outside in the afternoon sun and then using the pack hard (high speed driving) is a common way to trip this mode.

The highest I've ever seen is 108f but I don't operate my vehicle in the above manner. Charging overnight and parking in the shade go along way to keep temps in check.

 

i don't think the o/p has a pip, just trying to put his nimh lift back into ev mode.

 

Prius Prime EV does not equal Prius in EV mode. For example, Prius EV mode only goes up to 42-46 mph. Both PiP and Prime goes faster. EV mode on a Prius is not the same thing as EV mode on Prime. How many will buy a plug in that has to warm up the engine before EV mode is available like on a regular Prius? Very few.

There's no reason to believe 100F will be an issue as my PiP operates at triple digits without issue as does my friends C-max Energi.

 

In that case...
EV mode on a non-plug in hybrid is a convenience function that many use as gimmick. Toyota's intended use for it was for shifting the car a short distance, like moving it out of the garage to reach the lawnmover, without the ICE turning on, or to keep the ICE off when leaving early in the morning or return late at night in order to not disturb your neighbors. I believe those examples where in the Japanese owner's manual.

There is a list of a nearly a dozen conditions that will keep EV mode from operating in the manual. I believe Toyota didn't have EV mode available in the US at first, because they didn't want their dealers fielding calls from owners that didn't read the manual complaining about it not working.

Using EV mode at the right time might improve overall fuel economy. It is easier to over use it and impair that economy.

 

heck, even pip has a list as long as your arm. some run into them more than others, for whatever reason. can't say i've had the opportunity to try ev in 100+ weather, thankfully.
but i also think conditions before driving the car matter a great deal.

 

The EV mode in my Plug-in Prius (PiP) is the default mode if there is EV left. So if you start it up and there are EV miles left you stay in EV mode. When I want to precool my PIP while its plugged into the charger in my garage, I hit the A/C button on my key fob. The Remote A/C ALWAYS uses the battery but since my charger is 240V, it draws house current to replace what is being used by the battery and can keep up with the drain on the battery. If you plug into a 110V line the A/C will draw more than what is being replaced. And yes you have to be fairly close. Those with the Advanced model of the PiP can use their cell phone app to turn their A/C on. I'm assuming the Prime will have the same capabilities (Base - key fob, Advanced - cell phone app) except it will use a heat pump to help with cooling, much more efficient than just the A/C compressor. Supposedly the Toyota engineers made the Prime battery even more heat tolerant than the current PiP battery but that being said I have no idea what the upper limit is. The temps here only went above 100 once while I've had the car and after sitting in the hot sun for 10 hours it still stayed in EV and the A/C worked as expected. I would definitely take the Prime for a test drive but you might have to wait until next summer.

 

IMHO, the liquid battery cooling system in the Volt seems way more efficient than the air cooled system in most hybrids. Use the water that cools the car to keep the battery cool to the touch.

 

Water has greater heat capacity than air, so it will always be more efficient cooling. Also for heating, as the plug ins with it will heat the battery when it is too cold out. This reduces losses when charging and discharging the battery.

The down sides to using it is that it adds cost and weight. For the shorter range PHEVs, air cooling should be fine. the Enrgi's have been on the road for a few years already without reports of mass battery problems from heat.