Is it bad to turn off the Prius Prime just after it loses EV charge and goes into HV engine warm up (before it has finished its warm up cycle? For example, a few times I thought I had just enough EV charge to make it home before the EV battery ran out and went into HV mode. But the EV charge ran out just before I got home so the engine kicked in and started its warm up cycle. My husband said its bad to turn off a car before its finished warming up. But the problem is, I just arrived at my destination when the engine started. So I'd have to sit in the car waiting for it to finish its warm up cycle before turning it off and going inside my house....or else drive around the neighborhood in circles until it finally finishes. I just don't feel like doing that, I'm home....I want to go inside my home! But I don't want to damage the car by shutting it off just after the engine starts. Any thoughts?
it is bad on gen 3, but we have no known issue with gen 4. i would just shut it off, but try to learn to anticipate whether you can make it in all ev or not, and hit hv earlier if not. this takes practice.
My Prime hasn't done that but my Gen 3 did it a lot. I hope the prime doesn't do it too, but I really don't get into the same situation that caused it in the 3.
Yeah with my gen 3 if I wind up with it still in warm up mode I don't turn it off until the engine shuts down. That seems to prevent the cold start knock. Can be a bit of a pain, but the cold start knock makes it seem like the car is literally falling apart when it happens. I would have freaked out the first time if I hadn't read about it here first. I'm glad they have fixed it in gen 4 if they indeed have.
I read about it here in priuschat before I experienced in a Gen 3, so it didn't scare me too much. I agree that it sounds like something was drastically wrong!
Short drives were always hard on a car. The reason was primarily not getting a chance to clear out the exhaust system. It will deteriorate faster is water vapor isn't flushed out. That same situation applies to Prius. So, it's not necessarily bad, but isn't really good either. Avoid it when you can. If you know you aren't going to quite make it home on EV, might as well fire up the engine. Fortunately, you'll get really good at estimating distance after awhile. So, avoiding it may simply be running an errand sooner, rather than later.
or push the secret button that allows you to dig a little deeper into the battery and make it to your destination on ev.
Well, I try to let the ICE finish its warm up cycle before shutting down in both my Gen 3 and Gen 4. I've never experienced the knocking on cold start, but I don't want to either. One thing that does speed up the process is shutting off the climate control so that it does not keep the ICE running longer trying to warm the cabin. If you don't want to sit in your car when getting home, isn't there a "mode" that forces running the ICE to charge the traction battery? Can you switch to that mode as you approach your destination so that your ICE is warm when you want to shut down.
HV/EV button. You just push it to toggle modes. This is how you save EV for use later. That would help deal with the wait-for-warmup situation too. It makes the engine start, which results in a small addition to the EV range. Holding it for more than 3 seconds will engage CHARGE mode. So, if there's an opportunity of engine running for sake of EV benefit later, you have that option too.
True warm-up cycle of internal combustion engine actually takes a long time and is measured by oil operating temperature, not coolant / antifreeze temperature. Hence, short trip driving, especially in colder climate, is considered "extreme operating condition" by automotive engineers. Oxidation will eventually occur inside the engine block if a gas engine doesn't regularly go through complete heat cycles. If you want water and moisture to evaporate from the exhaust system and the engine block, oil must reach its normal operating range.... 190-210*F. For my cars, this takes about 15 minutes of freeway / highway driving in California's mild weather. If it was my Prime, I would run it in Hybrid mode through a complete cycle at least once a week. I would rather use some gasoline than have oxidation build up inside the engine.
Warm-up is far faster for the hybrid system, which is optimized for exactly that. 130°F is the usual engine-off threshold.
On Gen 3/4 Prius, there is an coolant loop to the exhaust system, to make the coolant warm up very quickly. How this effects the oil temperature, I don't know.
