Multiple Short Stops - Power Off or Leave On?

If your battery's charged and you don't leave high drain stuff on, you'd have to be awhile before the engine kicks on. If your display is off, only the power button or key light maybe the only things to indicate it's on? At least the theif would have to walk next to the car, look inside, AND be knowledgeable about Toyota hybrids (assuing Lexus & HIghlander would have similar systems). Possible... I'd feel very unlucky if it happened to me!!

Not sure if I would leave on with the key inside, but with SES vehicle would be disabled once theif turns it off. Only way I've found (and seems confirmed by forum) to leave car on and lock door is with manual key, it REALLY doesn't want you to lock yourself out! For all the trouble of using the manual key to lock and unlock, its rare I'll be so motivated... prob only time I'll leave it on is when dog is in car and it's hot and I want AC to keep car comfy for him. The added deterrent of unknown big dog hopefuly would keep windows intact! I don't think pooch would be all that amused even if I was the one breaking the window!

 

I think it is good to leave the engine on if you are going somewhere for say 2-5 minutes. If I drive say 30 mins and completely warm up the engine, a quick power off then on will still result in that 10-15 sec warm up where the ICE runs regardless. I really dislike this so leaving the engine on to avoid this will definitely help no?

 

Why leave it on? I think the missing factor here is WHY you combine short trips: to avoid the several-minute engine-warming-up phase during which you get worse mileage. Simply leaving the car "on" won't necessarily avoid that.

EDIT: Evidently turning it off and right back on will cause a short (a few seconds) engine run, but really, if your mileage is ruined by 45 seconds of engine running over the course of 3 stops, I'm not sure what to say. At some point, you become a slave to your car/mileage.

 

I agree for very short periods, when I have the car in sight; slipping
into 7-11 for a coffee.

Again I agree, especilly on "...up to a point." I try to keep my SOC in
the sixth blue bar at all times. This may be a personal problem
(Below that the power split device diverts power to MG1 to recharge
the HV battery, resulting in higher revs at a given speed, lower MPG.)
Having the car sitting in READY for even a few minutes eats up SOC,
especially if the air cond or heat is on.

While I can't prove it, my non-scientific observation is that most often
the abbreviated re-warm up period is preferrable to recharging the HV
battery.

One Gen II Prianista's unsupported opinion.

 

On hot days I regularly leave the car parked with the A/C running. I've figured the price several times, and it came out to about ten cents for a half hour. It's really nice to return to a car that cools you off, rather than one that bakes you for several minutes.

I turn the MFD display OFF, radio OFF, and sometimes block the speedometer display with a pamphlet laid on the dash. Parking brake ON, shift to Park, and lock the door with a $2 mechanical key that I keep on the keychain with the keyfob. Three warning beeps signals that I'm leaving the car in Ready. A continuous beep means I left it in gear (and had better move it to Park pronto!).

My idea of a hot day is anything over 90, so you folks in Arizona would probably pay more than the dime that I pay for 30 minutes.

The battery display is always down to pink bars when I return. The ICE cycles ON maybe one minute out of 5 to keep the charge up. People are accustomed to fans still running after you turn a car off, but I've had several people ask what was going on with the engine cycling ON unattended. I explain that the electric A/C is running, and the engine has to cycle on every so often to keep the battery charge up. The reaction is usually a rather glazed acknowledgement that somehow or another I'm running the A/C. The idea that the engine can cycle ON and OFF by itself is not something people are ready for.

The 2010 solar ventilation system would save some gas for me. Still, it would take a lot of dimes to pay for it. My next car will certainly have it, but my 2006 will have to do for a number of years.

 

Excellent post Rob. The only thing I hate is seeing the MPG go down when I am not driving. I wish there was a way to turn off its monitoring when the car was not in drive, such as the situation you described. Sure it technically is lowering your MPG, but I consider the change in MPG only to occur when driving. And thanks for the tip about locking the doors with the cut key. I was trying to figure a way to lock the doors when the car was on, I guess the cut key is the only way.

On a side note, about the air conditioner, I have 3 questions.

1. If you have the AC button on, but turn the fan off, does this use up any extra energy? I tend to turn off the AC button then the fan to be on the safe side.

2. When should I use the circulation vs. outside air. I don't really understand what they are used for to tell you the truth. I would imagine that using the circulation with the AC is probably more of an energy saver since you don't have to cool down air from the outside. My thoughts on the outside air is to be used only when the circulation is causing your windows to fog up.

3. I also notice that when driving, air still comes out of the vent even when the fan is off. I don't mind as its nice to get blowing air at no cost, but what causes this?

 

+1 for confusing the hell out of people, hahaha.

It really tickles me that they must leave thinking something very mysterious is going on...

 

Agreed. It's just that a cool car is more important to me than having a maximum MPG reading. Even when I use the A/C as described, the Prius still gets double the mileage of our BMW 325i.

I gave up fiddling with the A/C controls. I just leave it on AUTO. If I feel too hot, then I adjust the target temperature down with the steering wheel button. If I feel too cold, then I use the temperature up button. I also turn off the passenger side dashboard vents when I'm in the car alone (a fact that my wife regularly points out when she discovers that she's not getting any air...). In cold weather I sometimes turn on the defrosters for a while.

The problem with manually adjusting the A/C is that the situation changes quickly, and then you have to fiddle again. The AUTO function isn't perfect, but it sure cuts down on the fiddling.

I suppose you would use recirculated rather than outside air to maximize heating/cooling. I think AUTO does that already, using recirculate when it has a lot of work to do, and switches to outside when the temperature has reached the target. Recirculate is also useful when you don't want to breathe the outside air, like when passing through smoke. It's a disaster when you pick up something like dead skunk, as the car is already full of the odor by the time you realize there's a problem. Full open windows...

Before there was A/C, people just opened the windows and let the air blow through. I suppose that's what happens with the fan turned off. In a hypermiler contest, you'd probably do best with the windows closed, the fan off, and the vent on full outside air.

 

Thanks Rob, that definitely sums it up. I guess the minor hit in gas used with the auto AC will pay off when I crash because I fiddle with the AC too much. I usually just leave it on MAX COLD and have it on the lowest fan setting. I'll try Auto though. Thanks for clearing up the circulation questions to.