Ok to let Prius idle multiple times of the day?

I don't think there is any issue doing that, it was designed to be able sit in traffic which would be the same.

 

If by "sit idling" you mean remain parked in "READY" mode with the engine automatically stopped, and the transmission in "P," or with your foot on the brake and transmission in "D," neither of the motor-generators in the drive system are "on." No harm can come of that. Some electrical power is being consumed then, so if you're stopped long enough, the engine will eventually start to recharge the battery.

 

It may consume more electricity (and so eventually more gas) but it will not hurt anything but MPG.

 

no harm, no foul.

 

People use the Prius as an RV to camp where they leave it on all night. The only thing you do is use some battery power and the engine has to run periodically to recharge it. That takes gas, but it's not enough to worry about for a few minutes, even several times a day. There are others who use it as a backup generator when power fails to run refrigerators, etc., in their house.

 

It will tank your mpg, if you care about that. There is no free lunch: you run the hybrid battery charge down, eventually the engine wakes up. In some areas prolonged idling is actually illegal, mainly to cut pollution. Is there any reason you NEED to do this?

 

Unless your traction battery has a low charge the engine won't spin up.

 

In my experience if you idle for 10 minutes or less & the A/C is off you use less fuel compared to powering down & restarting.

 

That can't be right. You don't use electricity when the car is off, so for that small time-period (in which the ICE will not cool down enough) it can not be more fuel efficient to leave the car on.
And even when you leave the car on: if the ICE cools too much, it will start running.

 

Hey you can't argue with experience.

 

Actually you CAN use more fuel by shutting it off for 5 min then restarting rather than just leaving it in "ready" (sitting inside with A/C off etc). The reason is when you restart Prius goes into "cat warmup mode", where it runs the engine for no real reason, other than to satisfy the US EPA.

And, as they say in govt., YMMV!

 

I wouldn't say "no real reason", if it's in fact reducing pollution, by warming up the catalytic converter.

Guess I'm old-school: get where I'm going, shut it down.

 

Precisely my experience.

And in a 95F(35C) ambient weather with the car turned off for 5 minutes there is no way that anything has cooled off enough to require the 1-2 min of engine idling other than to satisfy some EPA emission mandate that is ironically actually increasing emissions. Heck there's traffic light & fast food drive-thru waits that equal or exceed those engine off(cooling) periods that doesn't require the engine to idle for so long yet it does when you re-start the car.

Just because it's required doesn't mean it's the best or most efficient way.

@Mendel: My most common scenario is I'm stopped at my storage until to load parts/tools for my business so I'm literally next to the car so leaving it "running" isn't a security concern.

 

Yeah I understand your aim is to preserve a cool cabin. We typically run windows down in nice weather. Then again the sun's on a bit more of a slant up here.

 

I do that when we go to the commissary. When I finish putting all the groceries on the conveyer, I go out to pull the car up to the curb so the bagger can load them. I leave the car running because the ICE is already running and if I turn it off, it'll just go through start-up again when things are loaded. I also like to cool the car for my wife and listen to the radio while I'm waiting for things to be loaded.

 

Ah you guys are all hellbound.

 

I leave my car running while I stay in the car while my wife shops. I suppose a very few Prius owners could be concerned with "cycles" on the traction battery and heat soaking it in very hot weather. That is, if it's left idling for longer than a few short minutes.

About a month ago I sat in the car in 105 F heat while my wife shopped. The inverter was charging the TP at 165 F and the battery was slowly going up in temperature. It got to 47 C. I didn't sit long enough to see where it would stop. At 50 C the ICE will run all the time to protect the battery. I was up to 52 C two days ago after the car sat in the sun all day at work. That was with front and rear window shades and side window deflectors (windows down 1 inch).

 

TB2 is the middle sensor on hybrid battery. Funny it alone is in centigrade, just oversight?

Nermind, see there's both units.

 

Right. It seems incredibly stupid to assume the "cat" will require warming after brief engine-off time parked with the car fully shut down, but not after a similar engine-off time parked in "READY" state, or after coasting down a long hill with engine off just as long.

It might still be more efficient to shut it down for a stop of a few minutes, if the engine will need to be running continuously after the restart anyway.