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Changing 12V battery

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by alfon, Oct 9, 2011.

  1. alfon

    alfon Senior Member

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    Has anyone replaced the 12 volt battery in their 2010 Prius yet?

    I am curious if it require much detail in removing and installing.

    Also I plan on keeping our Prius for a few more years and I have heard the 12 volt battery when it gets old will cause the car to use
    more fuel.

    Also my first choice for a battery would be the Optima battery that just came out for the Prius. Looks like that battery will last the remainder life of the car.

    alfon
     
  2. adamace1

    adamace1 Senior Member

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    It looks easy to me, you can go out to your car and remove the center cover in the hatch area then remove the little side cover on the right the 12v battery is right there. easy to get to.
     
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  3. alfon

    alfon Senior Member

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    Thanks, what happens to the computer system etc. when the 12 volt battery is removed, does the large traction battery than supply electricity to the computer system?
     
  4. Mendel Leisk

    Mendel Leisk Senior Member

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    You could hook up a low amp trickle charger at the under-hood fuse box before removing the 12 volt. I've got an old 1/2 amp motorcycle battery charger that works well, something like that should do.
     
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  5. alfon

    alfon Senior Member

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    thanks, good idea...
     
  6. duffasaurus

    duffasaurus Senior Member

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    I just installed the Optima Prius specific battery and it was a real piece of cake to install, truly plug & play. Inorder not to lose my presets, etc., I connected the new battery first to the battery connection points under the front fuse box cover. Removed the old battery & connected to the same connection points upfront. Then with the old battery still connected, I removed the new battery and installed it! You'll need two sets of jumper cables to do it this way!
     
  7. jdenenberg

    jdenenberg EE Professor

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    Just be sure to be careful with the positive lead since it will have live 12v on it if you attach a secondary source of 12v. Avoid the positive lead touching any metal parts.

    If your Prius loses 12v power the only impact is that you lose the radio presets, some computer data (your Prius will recover this in a couple of days) and the settings for the auto window open/close. It is easy to reset the windows by manually fully opening them and then fully closing them.

    Don't leave your Prius in READY as large sparks can fly if you allow the positive lead to touch metal and there is an expensive fuse that may open.

    JeffD
     
  8. alfon

    alfon Senior Member

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    Thanks for your info.

    I have a trolling motor 12 volt battery. So I can just connect up front to the the battery connection points under the hood fuse box.

    Than remove the old battery, install the new one. Than when the new one is installed I go up to the front of the car and disconnect
    the trolling motor battery from the fuse box points under the hood.

    Would that work as well?

    alfon
     
  9. Bill Collins

    Bill Collins Junior Member

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    would hooking up a Carry-Charge to the jumpstart points do the same . and then remove n replace the battery..
     
  10. almypal26

    almypal26 Member

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    :confused:How do you determine when it's time to replace the 12v battery? Time, miles driven or both?:confused:
     
  11. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    Here is a simple test, about 5/6 the way down this page

    Toyota Prius 12 Volt Auxiliary Battery with install kit for 2004 - 11

    If it is over 4 years old, if you totally discharged your factory battery, or if you start getting codes all over the car, you are a likely customer.
     
  12. Mendel Leisk

    Mendel Leisk Senior Member

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    I think any 12 volt source that's ok for hook up when the battery's in place would work. OTOH: the memory retentions don't need a large capacity, and I like to err on the side of caution: a small, low-amp trickle charger, the smaller the better, will do. They're pretty cheap to pick up too.

    There are some commercially available "Memory Savers" on the market, for this purpose. They're basically a 9 volt battery (the little rectangular one), and I believe they're intended to hook up to the 12 volt accessory outlet in the interior. Couple of issues: often these outlets are not hot unless the ignition is on, and sometimes the miniscule 9 volt isn't quite enough.

    The answer really depends:

    If environmental issue are your prime concern, you could drive use it till it fails. With this approach it helps to have a good digital multimeter, montitor it carefully, and hopefully catch it before it actually does leave you stuck.

    If you're an emergency response, do-or-die vehicle, then: every couple of years, or even yearly.

    Typical use, my 2 cents: I'd say every four years. Just a balance between reliability and environmental concerns. Couple this with periodic top-up with a smart charger, and checking it's state of charge with a digital voltmeter.