How to Drain the 12v

**TonyPSchaefer** · 09-30-2007, 07:55 PM

So I think I stumbled onto something this evening.

I have an air compressor that runs off a car's cigarette lighter outlet. To power the Prius' outlet, the car must be powered up. So this evening, while checking the tires, I powered up the car to [IG ON]. This is done by hitting the (POWER) button twice without your foot on the brake. This brings all the electrical systems online but does not engage the hybrid systems or start the ICE.

I did the driver's side first, passed the compressor through the front seats, shut the driver's door and did the passenger side. Due to the cord plugged in, I had to open the front passenger's door.

When all was said and done, I reached in through the passenger's door and pressed the (POWER) button to shut the car down. I shut the front passenger's door and walked into the garage. Realizing that I usually keep the compressor in the cargo area, turned around and walked back towards the Prius.

The lights were on.

You see, since the Prius doesn't have stock Daytime Running Lamps, I keep my headlights ON at all times. They come on when I power up the car and turn off when I open the driver's door. So why were they still on after I powered down?

I experimented:
1) Open the passenger door, power on the car to [IG ON], power the car off, lock the doors if you want, shut the passenger door. The lights stayed on.
2) Open the driver's door, power the car to [IG ON], power the car off. . . The lights immediately shut off.
3) Get in the driver's seat, shut the door, power the car to [IG ON], power the car off, open the driver's door. The lights immediately go off.

This says to me that the lights are triggered by the driver's door and only the driver's door.

Of course, the occasion is rare that you will not exit the car through the driver's door, but there are those times, few and far between, when you will find yourself reaching through the passenger's door to power down or parking close the on the driver's side and crawling across. For me, I used the same compressor last year to inflate my wife and my bike tires on the passenger side. Later that evening, my neighbor knocked on the door to let me know that the Prius was beeping and such; the 12v battery was drained.

Would someone go confirm that this is in fact a way in which a Prius owner might accidentally drain their 12v battery? I failed to check the dome light. If you don't have your headlights on, see if the dome light stays on.

seasalsa · 09-30-2007, 08:34 PM

Yes, that is how it works. Auot off only operates with the drivers door. This feature causing a dead 12v has been reported on several ocassions here on Priuschat

Earthling · 09-30-2007, 09:22 PM

And if you don't close the driver's or other door fully, the dome light will stay on all night. That won't help the SOC of the 12V battery.

Harry

qbee42 · 09-30-2007, 10:06 PM

Only the driver's door turns off the lights.

Tom

**TonyPSchaefer** · 09-30-2007, 10:22 PM

<div class='quotetop'>QUOTE(seasalsa @ Sep 30 2007, 07:34 PM) [snapback]519608[/snapback]</div>

Quote:

Yes, that is how it works. Auot off only operates with the drivers door. This feature causing a dead 12v has been reported on several ocassions here on Priuschat [/b]

Goes to show that I don't pay much attention.
Actually, I know there have been reports of drained battery, but I wasn't completely sure that there was a definitive explanation.

Neicy · 09-30-2007, 10:49 PM

How I killed my 12v: Had it in IG ON with fan on and didn't hear it + neighbor mowing lawn + bright sun shining on dash = didn't see dash lights or hear long beep when trying to lock car and left it ON! Lesson learned? Don't use ignition on unless you are sitting in the drivers seat the entire time.

09-30-2007, 07:55 PM	#1
TonyPSchaefer Your Friendly Moderator Join Date: May 2004 Location: Far-North Chicagoland Posts: 10,503 My Car: 2004 Prius Model: Package: #9 Thanks: 39 Thanked 165 Times in 106 Posts Friends: 23	So I think I stumbled onto something this evening. I have an air compressor that runs off a car's cigarette lighter outlet. To power the Prius' outlet, the car must be powered up. So this evening, while checking the tires, I powered up the car to [IG ON]. This is done by hitting the (POWER) button twice without your foot on the brake. This brings all the electrical systems online but does not engage the hybrid systems or start the ICE. I did the driver's side first, passed the compressor through the front seats, shut the driver's door and did the passenger side. Due to the cord plugged in, I had to open the front passenger's door. When all was said and done, I reached in through the passenger's door and pressed the (POWER) button to shut the car down. I shut the front passenger's door and walked into the garage. Realizing that I usually keep the compressor in the cargo area, turned around and walked back towards the Prius. The lights were on. You see, since the Prius doesn't have stock Daytime Running Lamps, I keep my headlights ON at all times. They come on when I power up the car and turn off when I open the driver's door. So why were they still on after I powered down? I experimented: 1) Open the passenger door, power on the car to [IG ON], power the car off, lock the doors if you want, shut the passenger door. The lights stayed on. 2) Open the driver's door, power the car to [IG ON], power the car off. . . The lights immediately shut off. 3) Get in the driver's seat, shut the door, power the car to [IG ON], power the car off, open the driver's door. The lights immediately go off. This says to me that the lights are triggered by the driver's door and only the driver's door. Of course, the occasion is rare that you will not exit the car through the driver's door, but there are those times, few and far between, when you will find yourself reaching through the passenger's door to power down or parking close the on the driver's side and crawling across. For me, I used the same compressor last year to inflate my wife and my bike tires on the passenger side. Later that evening, my neighbor knocked on the door to let me know that the Prius was beeping and such; the 12v battery was drained. Would someone go confirm that this is in fact a way in which a Prius owner might accidentally drain their 12v battery? I failed to check the dome light. If you don't have your headlights on, see if the dome light stays on. __________________ Proud father of Priapus: the '04 Tideland BC9 with an OEM EV button and sense of self-righteousness Current Mileage Chicago Prius Group Website Chicago Hybrid Group on FaceBook Find me on faceBook

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Which Oil Drain Plug To Buy	Smooth Operator	Gen II Prius Care, Maintenance and Troubleshooting	15	08-21-2009 11:38 PM
Drain valve...	ScottY	Gen II Prius Care, Maintenance and Troubleshooting	63	09-20-2006 10:10 PM
Why is there no drain in the windshield well?	PriusRos	Gen II Prius Main Forum	25	08-13-2006 08:12 PM
Battery Drain	skijapan	Gen II Prius Technical Discussion	1	08-03-2006 02:11 AM
HV Battery Drain	Tideland Prius	Gen II Prius Care, Maintenance and Troubleshooting	2	04-30-2005 09:46 PM

09-30-2007, 08:34 PM	#2
seasalsa Senior Member Join Date: Feb 2004 Location: Kent, WA Posts: 1,202 My Car: 2004 Prius Model: Package: #2 Thanks: 0 Thanked 1 Time in 1 Post Friends: 0	Yes, that is how it works. Auot off only operates with the drivers door. This feature causing a dead 12v has been reported on several ocassions here on Priuschat

09-30-2007, 09:22 PM	#3
Earthling Senior Member Join Date: Dec 2006 Location: Somewhere, NY Posts: 437 My Car: 2007 Prius Model: Package: #2 Thanks: 0 Thanked 1 Time in 1 Post Friends: 0	And if you don't close the driver's or other door fully, the dome light will stay on all night. That won't help the SOC of the 12V battery. Harry

09-30-2007, 10:06 PM	#4
qbee42 Senior Member Join Date: Mar 2006 Location: Northern Michigan Posts: 10,477 My Car: 2006 Prius Model: Package: #7 Thanks: 95 Thanked 391 Times in 290 Posts Friends: 10	Only the driver's door turns off the lights. Tom

09-30-2007, 10:49 PM	#6
Neicy Senior Member Join Date: Apr 2007 Location: Wakefield, MA. Posts: 804 My Car: 2009 Prius Model: Package: #2 Thanks: 5 Thanked 0 Times in 0 Posts Friends: 6	How I killed my 12v: Had it in IG ON with fan on and didn't hear it + neighbor mowing lawn + bright sun shining on dash = didn't see dash lights or hear long beep when trying to lock car and left it ON! Lesson learned? Don't use ignition on unless you are sitting in the drivers seat the entire time.