12 volt battery dead when parked 1 week

I've parked my 2006 Prius a few times for 3 weeks. It started up, no problem.

 

I parked my 2009 for 3 weeks because of the snow. It didn't start up, so I charged it with my Battery Tender. Left it on for a day charging. After that it started right up.

 

Did this problem always exist? If not, then odds are you did something to drain it the first time. Once that happens they're never the same again.

In any case you can test it without tools using the procedure here:
http://priuschat.com/forums/newbie-forum/73400-weird-stuff-happening-mpgs-dropping-test-battery.html

 

GD,You have a drain on your battery. Some small drain, such as a light in the glove compartment is staying energized. These things can be difficult to locate. If your under warranty bring it back to your dealer. If not under warranty find a good local garage specializing in auto wiring and lighting. Best of Luck

 

The fact is once a car battery goes dead it immed. starts to sulfate. Depending on how long it sat dead (sulfating) determines its future road worthiness or ability to just sit and keep a charge.
My personal experience is once a car battery goes dead and needs a charge its done. Once it starts to sulfate it does not stop.

Use that jump start to drive to dealer and buy a new battery or buy a yellowtop Optima which many posters seem to like as a replacement. Search.

That battery will now get you everytime. And also exposes you the worst of achilles heels on this car. The foolish reverse polarity ooops I made a mistake jump start. That usually will total our cars. For that reason alone a suspect battery on my Prius is replaced.

I will never jump start my car. So many posters on here reporting they correctly jumped there cars and now have $$$ thousands of dollars of damage.
I have AAA and it gets towed home and a new battery installed. But really don't have to worry as I always beep the car even in the garage.
Always.

Then I shut the lights off in the garage and take 2 seconds and look at the car in the dark and make sure no lights are on inside the car. That hatch ajar will get you.

And I have stored my car for 6 days with SKS on before and no problem started right up.

Did you kill the battery before with a light and now it won't stay charged at the airport?

They make battery disconnects but you'd have to go into the back well to the battery itself to get at it. A hassle at the airport but may be worth it to you.

6 seconds of Google reveals:

Here's a cheapie:
http://www.amazon.com/HF-Tools-Battery-Terminal-Disconnect/dp/B001S0EIK4

Here's real nice one:
http://www.amazon.com/Moroso-74101-Heavy-Duty-Battery-Disconnect/dp/B000CON4MA

BTW, always disconnect or switch the negative side of the battery.

Good Luck!

 

+1. Well, not 3 weeks; but certainly for 2 weeks at a time (business travel). The car has started right up with no long cranks. Maybe there is something wrong with the electrical system (as CarGuy posted in #5 above)?

 

There wouldn't be any long cranks because the power to crank the gasoline engine comes from the HV (traction) battery (201.6v nominal). When powering on the Prius, the little Aux 12v battery only has to start up the computers (ECUs) and switch a few relays to connect the HV battery.

 

Wow, what a common thread theme. It gets rehashed over and over. Maybe someone (I nominate Richard!) should write up an authoritative 12V battery guide to become a sticky?

- D

 

How 'bout if I add a few lines to
http://priuschat.com/forums/newbie-forum/73400-weird-stuff-happening-mpgs-dropping-test-battery.html

I should have posted that to the Gen II maintenance & troubleshooting forum, not the newbie forum.

 

i use to experience that problem, but no more...
1) purchase an Optima Yellow Top (which i did)
2) make sure that smart key is OFF
3) make sure that the vehicle is in total OFF mode (no beeps with door open) and no lights on

i just returned from an 8 day trip, my '06 started right up.

 

Nope. Not normal. I've never had my 12V battery die once in my 4 years of ownership yet.

Last year, I left the country for an 11 day trip w/my Prius parked (nobody else drives/shares my car) and the battery was fine when I returned. I'm pretty sure I disabled SKS. Within a month, I took advantage of the one week test drive of a Lexus HS 250h so my Prius was sat not driven for a week w/o issue.

 

You won't get "long cranks" a Prius due to a low 12V battery. The ICE in the Prius isn't and can't be started by the 12V, unlike on conventional cars. It's started by the big HV battery.

The Prius also has no separate starter motor.

 

Nice, sure that could work. Maybe it just needs to be in several forums.

- D

 

Nice, sure that could work. Maybe it just needs to be in several forums.

- D

 

I went to Costa Rica for 3 months, and my PRIUS started right up.
No battery problems here!!!!

 

The Prius 12V battery is like the Prius fuel tank in the following ways:

The maximum capacity of each is variable. In the case of the battery, the capacity depends on age and the extent to which the battery has deteriorated as it remains discharged for a prolonged period of time due to lack of driving time or leaving a cabin light on. In the case of the fuel tank, the bladder.

The available amount of Ah (in the case of the battery) or gallons (in the case of the fuel tank) can only be guessed. In the case of the battery, if the car is used only occasionally and for short trips, the battery may well be operating at only 25% - 50% charge over an extended period. The accuracy of the Prius fuel gauge has been commented on repeatedly, no need to rehash here.

Hence, no surprise that there is a wide range of experience regarding leaving the Prius for one or two weeks and then coming back to find the battery either dead or else willing to make your car READY.