Shut the A/C off?

Walker1 · 03-04-2006, 02:52 PM

I was told by a friend that if you shut off a Prius with the A/C and or fan motor running it can drain the car's 12 volt battery, the hybrid batteries, and possibly affect the MPG. Does anyone know if there is any truth to this? I personally leave the A/C and fan on when I shut the car off so I don't have to reset them again when I start the Prius again. Thanks.

Betelgeuse · 03-04-2006, 03:00 PM

Quote:

Originally posted by Walker1@Mar 4 2006, 03:52 PM
I was told by a friend that if you shut off a Prius with the A/C and or fan motor running it can drain the car's 12 volt battery, the hybrid batteries, and possibly affect the MPG. Does anyone know if there is any truth to this? I personally leave the A/C and fan on when I shut the car off so I don't have to reset them again when I start the Prius again. Thanks.

[snapback]220247[/snapback]

Well, it doesn't seem to me that it could drain either battery, but it certainly can't affect the hybrid battery. There's a relay that disconnects the hybrid battery when you shut down the car; there's no path for the current to flow, so you can't drain the battery.

galaxee · 03-04-2006, 03:00 PM

um, when you shut off the car the AC shuts off too.

not to mention even if it did stay on the HV battery is disconnected from the car upon shutdown. that's why you hear the relays clicking on startup.

i'd ask your friend where he got to be such an "expert"

Thomas Brock · 03-04-2006, 03:06 PM

I have noticed no problems with any of my batteries discharging after leaving the AC/ other stuff on when I turn off the car.

xbdude · 03-04-2006, 05:28 PM

I leave my AC on also (Florida, of course) and haven't had any problems.

keydiver · 03-04-2006, 06:59 PM

Quote:

Originally posted by Walker1@Mar 4 2006, 03:52 PM
I was told by a friend that if you shut off a Prius with the A/C and or fan motor running it can drain the car's 12 volt battery, the hybrid batteries, and possibly affect the MPG.
[snapback]220247[/snapback]

Maybe he's confusing it with leaving the car in neutral? That can run the battery down, but shutting the car off shuts the fans and A/C off too.

aaf709 · 03-04-2006, 07:27 PM

Quote:

Originally posted by galaxee@Mar 4 2006, 12:00 PM
um, when you shut off the car the AC shuts off too.

[snapback]220251[/snapback]

Also, if you have the AC on when you just hit the Power button (no foot on brake for ACC position), only the fans run, not the entire AC system.

nwprius · 03-04-2006, 07:36 PM

Keydiver:
You can not leave the Prius in neutral and shut it down. It goes into park automatically on shut down. No need to ever put it into park first. Of course you can leave it in neutral and walk away, with it yelling (long beeeeeeep) and of course it will run the 12volt battery down only; no HV battery involved.

darelldd · 03-04-2006, 08:18 PM

Start shopping for a new friend!

lwillis · 03-04-2006, 09:23 PM

I leave the HVAC system in Auto, but as it is winter time, I keep the AC on off. I've noticed about 2 mpg difference.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Do you shut the A/C when powering down the car?	Marvinh	Prius Main Forum	7	07-23-2007 03:56 PM
ICE Wouldn't shut off - 20-30 MPH	bigmahma	Fuel Economy	20	07-11-2007 12:29 AM
Proper way to shut down	splashback	Prius Main Forum	11	05-15-2007 12:36 AM
Shut down!!	treehuger	Prius Technical Discussion	11	03-06-2007 04:18 PM
My headlights don't shut off	AlphaTeam	Care, Maintenance and Troubleshooting	13	08-30-2006 06:25 AM

03-04-2006, 02:52 PM	#1
Walker1 Senior Member Join Date: Jan 2006 Location: FL Posts: 882 My Car: 2008 Prius Package: #2 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	I was told by a friend that if you shut off a Prius with the A/C and or fan motor running it can drain the car's 12 volt battery, the hybrid batteries, and possibly affect the MPG. Does anyone know if there is any truth to this? I personally leave the A/C and fan on when I shut the car off so I don't have to reset them again when I start the Prius again. Thanks.

03-04-2006, 03:00 PM	#3
galaxee running WOT until out of fuel Join Date: Mar 2005 Location: central NC/ western WI Posts: 9,066 My Car: 2005 Prius Package: #5 Nominated 5 Times in 3 Posts TOTM Awards: 0 Friends: 21	um, when you shut off the car the AC shuts off too. not to mention even if it did stay on the HV battery is disconnected from the car upon shutdown. that's why you hear the relays clicking on startup. i'd ask your friend where he got to be such an "expert"

03-04-2006, 03:06 PM	#4
Thomas Brock Join Date: Feb 2006 Posts: 87 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	I have noticed no problems with any of my batteries discharging after leaving the AC/ other stuff on when I turn off the car.

03-04-2006, 05:28 PM	#5
xbdude xbdude Join Date: Oct 2005 Location: North Central Florida Posts: 131 My Car: 2006 Prius Package: #3 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	I leave my AC on also (Florida, of course) and haven't had any problems.

03-04-2006, 07:36 PM	#8
nwprius Senior Member Join Date: Feb 2004 Location: Roy, Washington and Nanaimo, Canada Posts: 130 My Car: 2006 Prius Package: #4 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Keydiver: You can not leave the Prius in neutral and shut it down. It goes into park automatically on shut down. No need to ever put it into park first. Of course you can leave it in neutral and walk away, with it yelling (long beeeeeeep) and of course it will run the 12volt battery down only; no HV battery involved.

03-04-2006, 08:18 PM	#9
darelldd Prius is our Gas Guzzler Join Date: Jan 2006 Location: Northern CA Posts: 4,480 My Car: 2006 Prius Package: #6 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 10	Start shopping for a new friend!

03-04-2006, 09:23 PM	#10
lwillis Join Date: Sep 2005 Location: Russiaville, Indiana Posts: 37 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	I leave the HVAC system in Auto, but as it is winter time, I keep the AC on off. I've noticed about 2 mpg difference.