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Replacing hybrid battery with new OEM - transfer new cells to old batt?

Discussion in 'Gen 2 Prius Technical Discussion' started by odensc, Feb 15, 2023.

  1. odensc

    odensc Junior Member

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    My 2005 Prius battery is pretty much dead. I've spent $50 or so just replacing individual cells every few months but it keeps going out. I've decided to purchase a new OEM battery from a local dealer. I read that it doesn't come with the ECU or anything attached.

    Does anyone know if it's easier to just transfer the new cells to my existing battery housing, rather than transferring the ECU/relays to the new housing? I've replaced cells a few times now so I'm pretty comfortable with that process - but there aren't really any YouTube videos on how to transfer the ECU to a new OEM battery.
     
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  2. PriusCamper

    PriusCamper Senior Member

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    The modules, bus bars, wire frame, temp sensors and covers come fully assembled and already bolted down in an OEM pack. All you do is unbolt the part of the chassis that holds the relays, ECU and sensors and bolt it to the side of the new chassis that it comes assembled with, then plug everything in.

    Full install from start to finish takes about 2 hours, despite the liars at the stealership charging for 6 hours to do it. It's way easier than swapping out modules, like you've done in the past.
     
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  3. odensc

    odensc Junior Member

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    Thanks for that info. If it's easier than replacing modules then I would feel pretty confident. Even a local independent shop was quoting $650 for labor, so I figured I might as well do it myself if I've already done it before.

    Will report back once I do.
     
  4. PriusCamper

    PriusCamper Senior Member

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    Yeah... I installed a Nexcell pack for someone last week and charged $48 per hour for 3.5 hours of work and he paid me $400 and gave me a stern lecture about how I was highly skilled at this work and that I was making myself look sketchy and unprofessional by only charging $168 when most people charge more than $500 for an install. Lol...
     
  5. ColoradoCrow

    ColoradoCrow Active Member

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    @nancytheprius just did this on a blue Gen 2. not to long ago. She had some great pictures of the 2 units side by side. Maybe she has a few more?
     
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  6. TMR-JWAP

    TMR-JWAP Senior Member

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    How in the world have you replaced modules several times but have no understanding of swapping the electronics section of the old battery to the new battery? Maybe this is part of the problem why you have to do it every month? Can you describe how you're doing module swaps?
     
  7. odensc

    odensc Junior Member

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    Not sure where you read that I had no understanding. I'm sure I could probably do it, I'm just hesitant of working on my only car without having any tutorials/documentation on hand in case I get stuck or do something wrong.

    I've been doing it so frequently because I've just been replacing the modules from whichever block looks dead in Dr. Prius. Haven't been rebalancing the pack or anything because it's 17 years old and I'd rather just replace the whole thing with an OEM battery now to give it another 15 years of life.

    Just followed this video the first time but now I follow this one as he shows how to remove the battery without having to remove side trim.

    Perhaps I was asking a stupid question originally, but it seems like I got my answer: that it should be pretty straightforward to just swap the electronics. Thanks all!
     
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  8. ColoradoCrow

    ColoradoCrow Active Member

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    Thanks for the link to the second video. I used the older method.....before but had to since I was replacing the rear struts. Hardest part of that job is removing the body panels and brackets to get to the rear shock bolts. LOL. Thanks. Good luck with the swap. From what I can see in #Nancytheprius pictures the Ecu is pretty much unfasten move over and rebolt.
     
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  9. TMR-JWAP

    TMR-JWAP Senior Member

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    I guess what I'm saying is that if you're swapping modules in such a way that you haven't even experienced disassembling the battery or even just removing/reinstalling the electronics section, that is very likely the reason you have to keep doing it over and over.
     
  10. nancytheprius

    nancytheprius Active Member

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    I have not read all of the posts below, but I was originally under the impression that it would be. THEN the OEM battery came with the new modules already assembled in a new housing. so, I think transferring the ECU and other components is really the only way to go. I did this in November without any videos or material and was successful. If I can do it, so can you!
     
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  11. odensc

    odensc Junior Member

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    Update - got a new battery from the dealer for $1950 (after core return). Called 3 dealers near me and all had the same price.

    The install was indeed straightforward. Three 10mm bolts attaching the electronic stuff to the battery chassis, and then of course unplugging and reconnecting everything.

    The battery wasn't fully assembled, it had a few wires in a separate bag. I put them in place but didn't actually connect them to the battery until I was done transferring the electronics, for safety.

    Honestly, the hardest part was opening up the huge crate. :)

    PXL_20230301_055333860.jpg

    The difference in acceleration was immediately noticeable, even compared to when I first got the car and it had no battery issues. Brakes are also way more responsive, interestingly.

    Definitely glad I spent the extra few $$$ for a new OEM. Should outlive everything else on the car now.
     
    #11 odensc, Mar 1, 2023
    Last edited: Mar 1, 2023
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  12. Likeawind

    Likeawind Member

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    Is it hard to put together the electronics? I can get a brand new battery from a dealership for $1635 plus tax in Houston. How is your battery going so far?
     
  13. odensc

    odensc Junior Member

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    IMO it was easy. Nothing is really that complex, just takes some time to transfer everything, and it's a bit hard to work in the small space. Make sure to take a bunch of pictures for reference before you start disassembling the old one!

    Battery's still good, haven't had any issues since replacing. $1635 is a great deal; I'm jealous. Good luck, you should have no problems!