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    Bob the Builder Junior Member

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    Hi all I am new to the forum. I have the part number for the battery. It is a series D51 Optima # N9951 YEL ( Napa auto parts )$149.00. You need a new positive post bracket with stud attached(standard post size, since the old one is smaller than normal) and a universal ground bracket with the clamp for a wire install. Cut off the ground clamp ( old one) and install the wire to new one. Look at the positive post ( old one ) and get a new one with the same configuration with the post bolt. Unbolt the positive unit from the old bracket and install new one. The Optima is the same size as the old one so everything goes back under the cover. It is a non vented battery so you do not need the hose hooked up to it. I tried to get one everywhere and after visiting your site I found a web sight that showed the right part number. Most sights want to sell you their kit. If you are not good with electrical connections get the terminal kit from the web sight. Then it is just a matter of unbolting the battery and replacing the cables ,connectors and your done. Thanks for the advice on this sight guys.
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    bisco cookie crumbler

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    thank you bob and :welcome: to p/c!
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    David Beale Senior Member

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    It IS a vented battery, and you SHOULD connect the vent tube. It only vents in case of a problem, but that would be enough to fill your hatch area with not so nice gas'. Look around the side of the top and you'll find a vent hole. That's where elearnaid have you plug in their vent adapter.
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    kohnen Grumpy, Cranky Senior Member

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    Or, you can buy a kit that is specifically made for this conversion:

    Toyota Prius 12 Volt Auxiliary Battery with install kit for 2004 - 10
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    BROOK SIDE New Member

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    GuamKelly Member

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    III
    I can't think of a single reason not to buy the battery and complete kit from here:

    Toyota Prius 12 Volt Auxiliary Battery with install kit for 2004 - 10

    Their customer service was superb, the shipping was extremely fast, the item was beautifully packaged, and everything I needed, including directions, was right there.

    BTW, you are badly mistaken about not needing to vent the battery -- under certain conditions it could emit enough hydrogen gas DIRECTLY INTO THE CABIN to ruin your whole day. Vent it properly. If you can't figure out how and have already done everything else, call the nice people at elearnaid.com and I'm sure they'll sell you that bit all by itself.
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    Hal W New Member

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    How much extra for the Kit? Do they sell the vent fitting only? It is not a difficult thing to replace a battery clamp! Hal
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    jdenenberg EE Professor

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    $20 - It includes Cables with connectors, a vent tube adapter and instructions.

    Installation Kit for Optima battery in Prius

    JeffD
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    David Beale Senior Member

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    I bought the kit late last year. It's sitting on a table in the basement waiting for the original battery to die. Looks like that may happen this year, as Pearl is now running at 13.9V instead of 13.8, but time will tell.
    Yes, you could save about $10 by buying the battery terminals and cable locally. I just got the kit. It was worth the $10 to have them do the research and shopping for me. I'll get the battery from Battery World here in Edmonton when I need it.
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    Hal W New Member

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    Are you on the original battery David? Probably just as well off with the OE replacement? Hal
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    mikepaul Senior Member

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    So, is 7 years 2 months on the original battery exceptional or just pretty good?

    I keep thinking about it (mostly the cost) just like I think about the HID headlights that HAVE to be close to retirement...
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    Octane Proud Member of 100 MPG Club

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    I needed a battery for my 2007 and was impatient so I bought an OEM battery. Dealer wanted $190. I asked for wholesale price and he sold it for $125. Car has 90K so this battery should last life. Why not go OEM?
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    Bob the Builder Junior Member

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    Thanks for the feedback. The battery dealer said it was not a vented battery. I am sure Optima has a vent tube for their batteries, as the hole is in the side of the top. You guys are great. I will let you know if the mileage goes up as I have heard. Bob
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    Hal W New Member

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    Hey Bob
    Apparently there is a fitting in the kit so you can vent the YT battery the same as OEM battery. Did your kit not come with this? Hal
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    jdenenberg EE Professor

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    Bob,

    The MPG only goes up if the old 12v battery was continuosly asking for excessive charging current (as in a shorted cell). Otherwise you will see no change (except that your Prius is more likely to start :) ).

    JeffD
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    BROOK SIDE New Member

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    Had no effect on mileage when i installed it in my prius, however i do feel it is a more reliable battery.
  17. Online

    Mendel Leisk Senior Member

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    It's a good run. My approach: just replace the OE battery, with an new OE battery, every 4 years, regardless of it's behaviour/condition.

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