PHEV Thermal Efficiency

[falkin42]

Hi, I've been reading for a while without an account but I thought I'd ask a question. I'll probably introduce myself in the appropriate area now that I think about it but back to this thread (I'm very bad at forums, sorry). I've tried searching but I couldn't find anything or don't know the right words.
How does a PHEV work in regards to (what I've been calling in my head) thermal efficiency? Since the combustion engine needs to reach its operating temperature to be most efficient, would not running all the time interfere with maintaining heat in the block? If the car runs in EV mode long enough, would the combustion engine cool too much?
It occurred to me that I might be making too much of it, and that the engine will probably be running or not, and that there wouldn't be that much on and off but I'm curious what y'all have to say.
If there's a thread I should read then by all means direct me to it. You seem like nice people for the most part so I'm hoping I won't regret opening my mouth.

[ksa8907]

Once the ev portion is exhausted, the vehicle will switch over to normal hybrid function. So, once the engine comes on it typically won't be off long enough to cool down.

[redpoint5]

Prius has tried 2 strategies for that problem. One was to use the exhaust gas to warm up the engine coolant quicker, and the other was an insulated reservoir to store coolant.

[serialk11r]

AFAIK engine efficiency isn't *horrible* as long as it's sort of warm, since the main problem with a stone cold engine is fuel not mixing with air and burning, perhaps sticking to the walls. The combustion chamber walls are extremely cold compared to the actual gases even at full operating temp. At say 160F instead of 200F, your engine clearances are okay and the fuel vapor pressure is high enough to burn effectively.

But yea having a water cooled exhaust manifold to transfer more heat to coolant also helps. It's a pretty standard design feature nowadays, since it simplifies the exhaust and reduces warmup time.

[Hersbird]

On our van most days the engine never starts at all. Then on the days when it does it warms up once like any other gas motor and then holds the heat fine for any times it shuts down. It's only off for a few minutes here and there like downhills or stopped at a light, not long enough to get cold again. For us using the gas motor is only about once a week or every two weeks.
We bought it 2.5 months ago and still have over 1/4 tank that the dealer put in. I think 200 gas miles and over 1000 electric. In a few weeks we go to Seattle and back so will get probably almost exactly the opposite over 4 days.

We just got off a different 1300 mile vacation zig zagging Montana and Wyoming in a Hemi Jeep pulling a teardrop camper getting 12.5 mpg so it will be nice to do the same miles on maybe 2 tanks in the van.

[jakobnev]

Hersbird -

What kind of van is this?

[redpoint5]

Originally Posted by jakobnev

Hersbird -

What kind of van is this?

Pacifica Hybrid. It's the only plug-in minivan, and might be the only hybrid minivan.

[S Keith]

Originally Posted by redpoint5

Pacifica Hybrid. It's the only plug-in minivan, and might be the only hybrid minivan.

Not anymore.

2021 Toyota Sienna is only available as a hybrid.

CORRECTION: Pacifica IS the only PHEV minivan.

[Hersbird]

Yeah, a 2021 Pacifica Hybrid. We looked at the Toyota but between the basic model the Pacifica had on the lot, the $7500 tax credit the Toyota doesn't get, and the $5000 Chrysler rebate vs $1500 on the Toyota the price difference was huge. Ultimately we will be about $30,000 into our Chrysler which I think it just might still be worth at the 1 year point in which case we will do it all over again next year but maybe with a different PHEV. Not that the Chrysler is bad but we ended up keeping our old van so a Rav 4 Prime or a Jeep 4XE would really suit us better.

I did finally put some gas in the Pacifica, filled it to check mpg. It went 304 miles gas and took 12.0 gallons so 25.3 mpg. Not as good as I hoped considering most of that 304 would be highway but one trip, about 100 miles of that we did have 2 kayaks on the roof. It also is trying to charge the battery off and on when in hybrid mode so some is going to later add to the electic miles. The computer said we were getting 48.9 mpg but I don't know how it calculates mpge. A total of 941 EV miles and 304 gas on 12 gallons is pretty sweet IMO. For a long time I was over 90% EV but vacation started and we started on longer trips. That's pretty much what makes it work for us vs a pure EV, that or we would have had to use one of our other older cars. Oh and there aren't many new EVs worth buying at $30,000. The base Volt would get there if they got back the fex tax rebates.

[redpoint5]

The Volt was discontinued. I don't think they have any PHEVs anymore. The RAV4 Prime is what I'd be tempted to get, if you could find one available. For some reason Toyota is severely limiting production, and it might only be available in CARB states.