Hybrid system appears to protect cold engine

[theorist]

One of the benefits of the hybrid system that I appreciate is that it seems to protect the internal combustion engine when cold. That the more powerful traction battery is able to crank the engine at higher speeds and the thermos (in the American version) can sometimes help a parked engine conserve a little heat have been well covered. I'm thinking of how the Prius seems to place very small demands on the engine when it's cold.

In the winters here, I would often get a little too worried or frustrated asking my wife to drive her old Civic very slowly till the engine warmed up. I could feel the engine struggling when well below freezing, even with 0w-30 Mobil 1. I was worried about altered clearances or gaps between parts due to thermal contraction and expansion. Perhaps I was being too anal to worry about this. I would cringe when she would start up in the morning and being late to work, head out with a firm foot on the throttle.

I haven't driven the Prius in the winter yet, but from spring and summer use it seems that this may become a non-issue with the Prius. It seems that when the engine is cold the hybrid system places very low demands on the engine. It runs the engine or ICE but also pulls from the battery for anything beyond very gentle acceleration.

I haven't driven a Prius for more than a few days in the winter and don't have CAN-view. Can others with more data verify my conclusions?

For years Toyota and other manufacturers have advised drivers to warm up an engine by driving the car gently. The hybrid system seems to use the battery to substitute for engine power when cold, enabling the driver to drive normally while the engine warms up gently. I hope that this is one more way in which the hybrid system will improve the longevity of the car.

[john1701a]

After *SIX* winters driving a Prius in Minnesota, I can most definitely confirm that the system is more protective of the engine than anything else you have ever encountered... including a Prius in the warm season.

Look at it this way, the battery-pack prefers the cold. It doesn't have to worry about getting too hot then. So more generous use of electricity in the winter is no big deal.

[Frank Hudon]

on my Classic the first 3 minutes or so will draw up to about 60 amps and the ICE will hardly rev up, most I see is about 1600 RPM. Once past that threshold the ICE will rev as normal but the first bit it's the cat coming up to temp and the retarded cam timing the sends a warm rich mixture in to the cat. I see a simular effect with the wifes 2k4 and CAN-view but the effect seems to me to be limited unlike the Classic. I'm sure those that drive a G2 with CAN-view will give more information on cold current draw till warm. Don't worry about a Prius in the cold it will prevent you from causing damage.

[hdrygas]

I was going to start a new thread on this but I think the Thermos is truly amazing!! Before this last 10 days I thought it was a "nice" after thought, but now I know better. I let my car sit for 10 days. I would guess that the thermos was at ambient temp for the night. I came home late in the day and the temps were in the mid to high 80's and started "Belle" up. The engine temp was low and after the dump from the thermos even lower. The really amazing thing is that it took me nearly half the route I usually go to work etc to get the car up to 161 degrees F. During the summer with or without the block heater this is unheard of. Last summer with the temps in late afternoon at 86-88, I was above 161 before I got out of my development (.3 mi) It took me almost 1.3 mi to get "Belle" up to operating temp. I will never discount the thermos again!! It works, it is valuable and not a minor contribution to the efficiency of the Prius!

[Frank Hudon]

as I don't have a thermos on the Classic I'm still using the umbilicle cord and this morning with 2 1/2 hours it had the ICE at 130F+ 56C for those that can convert and I was in S4 6 blocks from home. I doubt that the 2k4 with the thermos would do a lot better. If she could park it so that we could plug it in I'd install a block heater in it.

[ScottY]

I see this every morning with CAN-View. When I just start driving, it's putting up to 80amps and never rev above 2000 rmp during warmup. To be fair, I never try to floor it when it's warming up.

[nerfer]

<div class='quotetop'>QUOTE(hdrygas @ Jul 10 2006, 09:52 PM) [snapback]284235[/snapback]</div>

I was going to start a new thread on this but I think the Thermos is truly amazing!! Before this last 10 days I thought it was a "nice" after thought, but now I know better. I let my car sit for 10 days. I would guess that the thermos was at ambient temp for the night. I came home late in the day and the temps were in the mid to high 80's and started "Belle" up. The engine temp was low and after the dump from the thermos even lower. The really amazing thing is that it took me nearly half the route I usually go to work etc to get the car up to 161 degrees F. During the summer with or without the block heater this is unheard of. Last summer with the temps in late afternoon at 86-88, I was above 161 before I got out of my development (.3 mi) It took me almost 1.3 mi to get "Belle" up to operating temp. I will never discount the thermos again!! It works, it is valuable and not a minor contribution to the efficiency of the Prius!
[/b]

Are you saying your commute is under 3 miles? (~1.3 * 2) Why not ride a bike? Disregarding that, how do you get such good mileage numbers on such a short commute?

I'll agree though, the thermos is a good idea, one I didn't know about until I had the car.

[jayman]

<div class='quotetop'>QUOTE(Frank Hudon @ Jul 10 2006, 10:21 PM) [snapback]284258[/snapback]</div>

as I don't have a thermos on the Classic I'm still using the umbilicle cord and this morning with 2 1/2 hours it had the ICE at 130F+ 56C for those that can convert and I was in S4 6 blocks from home. I doubt that the 2k4 with the thermos would do a lot better. If she could park it so that we could plug it in I'd install a block heater in it.
[/b]

Frank:

With your record-setting heat wave, I bet you really scare the neighbors by still plugging in your car.

The first winter I had the car, before I made the winter front, at -40 I can confirm the Prius is VERY eager to use the electric motor. True I have underground heated parking at my condo, but after parking for a few hours outside at a mall, I could easily dust other cars that were barely moving.

Actually, at temps much below -20 C, there is always excess SOC. I really wish Toyota had used that charge to run supplementary high voltage heaters. Before the winter front I just about froze some parts off.

jay

[hobbit]

It's been amply documented over in the prius_technical_stuff
yahoogroup that startup behavior does indeed propel you *solely*
on battery for the first 30 seconds or so, while the retarded spark
and richer mixture causes, as a listmember so aptly put it, huge
flames roaring down the exhaust manifold to get the cats warm. Then
things level out and become sane and allows the engine to start
contributing useful propulsion. If you start up and immediately
ream it, however, the engine *will* get a higher load placed on it
right then, from stone cold, and that's probably a bad idea.
.
So when you start cold [or as cold as the thermos-pumping cycle
leaves the block] you can go immediately but try to be gentle and
NOT let the engine RPM increase at all for the first minute or so.
It's not ready yet. If you listen carefully, you can hear a subtle
shift in the running sound -- less of that metallic sort of noise
in the exhaust that comes from spark retardation, perhaps replaced
by a little bit of inverter whine as MG1 starts receiving a load.
.
_H*

[jayman]

<div class='quotetop'>QUOTE(hobbit @ Jul 12 2006, 09:59 AM) [snapback]284940[/snapback]</div>

If you start up and immediately
ream it, however, the engine *will* get a higher load placed on it
right then, from stone cold, and that's probably a bad idea.
[/b]

H

That's a bad idea with any vehicle, not just the Prius

j