I know this has been discussed many times in other threads. But, I havent found simple answers to my questions I have a 06 package7 with 38,000 miles and want to replace the 12 volt battery. I did the various battery tests as mentioned in other threads and my battery is failing and low on voltage. I forgot exactly what it measured, but it was lower than where it should be. My questions are as follows: 1) can I just simply disconnect the current 12 volt battery and replace it without having to do any kind of powering down? 2) if I wanted to keep all my current convienance settings(radio settings etc) how and where do I connect a aux. 12 volt battery? I read hobbits sp? page and couldn't identify where to hook it up. 3) if there is anything else I should be aware of, please advise. Thanks in advance for your time. Larry
You can hook up a spare 12 source like you hook up jumper cables to jump the car. Its under the hood.
Yes, you could replace the 12V battery without bothering to hook up a backup power source, you'll just have to reset the driver's side window auto up/down and your radio station presets. You'll also lose your trip odometer readings and the fuel gauge will take a few minutes to show the correct reading. Not a big deal. When disconnecting the terminal connectors, remove the negative side first, you'll probably find it is easier to disconnect the cable where it connects to the body. The main issue to be aware of is to make sure you observe the correct battery polarity when reinstalling the battery terminal connectors.
I own a 08 group 6 Prius that I am very happy with, I have had no real issues other than tire punctures that no one is willing to repair, I have had to replace 2 in 2 years, Not cheep. My other issue I have had twice is dead 12 V battery. Both times were my fault as I did not get the hatch closed both times, jumoed started both times and no other issues sense then, My question on the 12v battery is a selly one. Where is it? I have looked almost everywhere but have not seen any thing that even resembels a normal 12v battery. Paul
Hi Paul, Open the hatch. Find a triangle-shaped piece in the hatch floor in the right-rear corner. Remove that piece (you probably have to remove the folding hatch floor and the black plastic tray over the spare tire first), and you will see the 12V battery.
Accessible via the hatch, your 12 volt battery is in the right rear corner of the car under the small panel level with the hatch floor on the right side. See here for some pictures: http://techno-fandom.org/~hobbit/cars/prius-12V/
I've seen a lot of mechanics use a cigarette lighter adapter hooked up to a small 9v battery and plug it into the cigarette lighter socket. It will put forth enough current to keep your radio presets and such current.
Unfortunately that won't help with Prius because the 12V auxiliary power sockets are not connected when the car is IG-OFF.
Darn! I forgot about that. I assume everyone has the Coastal mod. I have not tried it but it would work then yeah?
Thanks guys, I will end up just attaching a 12 volt battery to the jump terminals under the hood while I change the prius 12v battery!
In that case, when you are removing the positive battery terminal connector, you should exercise extreme caution. If your wrench touches the car body while in contact with the positive battery terminal, you will short the 12V battery in front of the car, via the Prius battery cable. Depending upon the capacity of that battery and the resistance in the wiring, in a worst-case scenario that could pop the 120A MAIN fuse in the terminal fuse block, cause a big spark (which is always an unsafe thing to do around a car battery), or at minimum scare you to death. When I replaced the 12V battery on my 2004 a few months ago, I used a lab power supply attached to the positive jump start terminal and one of the nuts that secures the top of the driver's side strut mount. The lab power supply is current-limited to delivering 2A current, so it's not a big deal if the positive terminal is inadvertently shorted to ground.
I plan on using a 12 volt lithium polymer battey for the back up power. Its one of those small rc helicopter batteries. To be exact its a 2100 mah 12.3 volt battery. Also, I called the dealer and the cost for a replacement 12v prius battery is 117.00 plus tax. That is expensive, but in my opinion not too horrible of a price for a factory replacement.
OK, the backup battery sounds like a good choice: not too big, not too small. Also, your dealer's price is excellent. Usually the price is more like $130-$140 at the parts counter.
The price at the dealer was 137.00 I simply asked for a discount and the parts guy said "sure no problem, if it gives me the sale I'll do it" He gave me 20 bucks off I was actually surprised!
