Dead 12 V Battery

<div class='quotetop'>QUOTE(Rick Grahn @ Dec 28 2006, 06:55 PM) [snapback]367856[/snapback]</div>

Coupla things:

1. if the battery is going dead that quickly, you've got excess dark current somewhere; that is, even when the car is officially "powered off," something is drawing down the 12v battery when it shouldn't. Have you checked to see if the JBL audio system is malfunctioning?...this is known to cause problems similar to what you've described.

2. Don't know about the fob storage issue. I can tell you that the SKS looks for the presence of a fob every second or two...but what the innards of the car do after it finds it, I don't know. Normally, (as you know already) that the interior lights come on when the SKS transceiver senses the fob. But they go off, too, after a bit of time, if you don't enter...do you think something like this is happening, where the interior lights are somehow coming on periodically due to the presence of the fob...or, there's a fault somewhere and the interior lights stay on?

Other than that, I can't of anything that's powered up under these circumstances...but I could be mistaken.

Have you tried NOT storing the fob so close, or simply turning off the SKS for a while? Seems to me to be the logical thing to try next. But if you've been having this problem before storing the fob so close, it's definitely time to figure out what's 'on' when it shouldn't be.

 

If the car is locked with the fob remaining near the car, the car and fob will continually 'talk' for a while. The Prius is programmed to stop 'talking' after a while. I believe it is 10 minutes if the fob is near, and it will stop looking for the fob after 5 days.

I would go with Pinto Girl's suggestion in verifying the problem is/isn't SKS by turning it off for a bit. You could be getting an abnormal drain from somewhere else.
Also note, Headlights left in the ON position and relying on Auto-Off can also create an increased drain on the 12V battery.

The way all the electronics work, is all the components are provided with high current unswitched 12V, with switched low current 12V to turn on the devices. This is much like how modern aftermarket auto audio amps and radios work. So if an ECU/Electronics malfunctions, it could remain 'ON' and drain the battery even though the car is actually off.

 

See:

http://www.buchanan1.net/lead_acid.shtml

11.4 is definitely too low. Make sure no lights are on when you measure though. The car readout is not really directly at the battery.

 

<div class='quotetop'>QUOTE(Rick Grahn @ Jan 3 2007, 08:42 PM) [snapback]370495[/snapback]</div>

Had a very similiar experience with my first Miata in the early 90's. Added a Sears cruise control and added the hot wire to the radio fuse since the radio didn't work without the car running. Had two dead batteries and probably had one replaced under warranty before using a bigger flashlight and voltmeter to figure out that I had chose the radio fuse that also ran the clock so it was always on.

 

<div class='quotetop'>QUOTE(Rick Grahn @ Jan 3 2007, 09:42 PM) [snapback]370495[/snapback]</div>

Oh well, s*** happens.

When you consider the capacity of that little 12 vdc battery, yeah there you go. Make sure you fully charge the battery now that you've - hopefully - uncovered the problem.

 

Nice diagnosis...glad you found it.

I'm adding this to my mental list of 'what ifs.'

 

Rick,

Kudos to you for sharing the reason behind the battery drain - as embarrassing as it is (and it shouldn't be for you really, you left it in the hands of professionals) was, we all still learn from these experiences. I appreciate it, FWIW.

 

<div class='quotetop'>QUOTE(Rick Grahn @ Jan 3 2007, 11:42 PM) [snapback]370495[/snapback]</div>

Assuming it was even in "standby" mode while you car was off. If all you did was turn off the car, expecting the DVD player to turn off, then it might not have ever gone into standby.

 

<div class='quotetop'>QUOTE(Tideland Prius @ Jan 10 2007, 07:44 PM) [snapback]373870[/snapback]</div>

Could be if the battery is already in a partially discharged state, it wouldn't take much to drop below 10 volts.

 

<div class='quotetop'>QUOTE(Tideland Prius @ Jan 10 2007, 11:54 PM) [snapback]373981[/snapback]</div>

Well, the OP did state the person who installed his DVD player made a booboo with the wiring, so there was a constant drain on the battery. Like any lead acid battery, once you discharge it often enough, and leave it in a partially charged state, you will damage it. You will also experience sulfation.

So not only will the battery be only partially charged, it will also have much reduced capacity. If you catch the problem in time, and have access to a battery charger with built-in desulfation, you can usually save the battery.

 

<div class='quotetop'>QUOTE(Rick Grahn @ Jan 2 2007, 08:58 AM) [snapback]369530[/snapback]</div>

Rick:
I have 2005 prius also. What is the (diagnostic screen shows 12.4 Volts) that you refer to in this post?
Dick K :blink:

 

Rick, did the installers explain why they ignored your instructions?

Also, what is the intriguing ACC diagnostic screen you mentioned?