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DIY cell replacement

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by shonna, Sep 27, 2020.

  1. shonna

    shonna Junior Member

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    I have a 05 prius. Had error code stating issue with hybrid battery. All cells were charged to 7.7 with the exception of two that are at 6.5. Can I recharge those two or what is the best place to get the two cells that need to be replaced. Thank you.

    Posted via the PriusChat mobile app.
     
  2. dolj

    dolj Senior Member

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    No, you can't, those two modules are done and need to be replaced. They cannot be charged, as at least one cell inside the module (there are six cells in total) has failed.

    If you want to change the two modules yourself, contact @ericbecky or Hybrid Automotive and they should be able to supply you with good replacements at a reasonable price. Beware of random online sellers of used modules.

    There are also a few members of PriusChat who might be able to also help. If they can they will maybe PM you directly.
     
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  3. bisco

    bisco cookie crumbler

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    where are you located?
     
  4. shonna

    shonna Junior Member

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  5. Isaac Zachary

    Isaac Zachary Senior Member

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    I had a similar problem. I did what everyone told me not to do and ordered some Gen3 modules and replaced the bad ones. So far it works pretty well.

    All the modules have 6 cells in them, and each cell is usually around 1.2 volts or more. 1.2 x 6 = 7.2 volts, so anything above that is good. But if one cell dies in a module it's voltage is lost. 7.2 - 1.2 = 6 volts. So between 6 and 7 volts means it has a dead cell.

    Another thing I did was test the capacity of all the modules. A couple were noticeably lower than the rest, so I replaced those too.
     
  6. shonna

    shonna Junior Member

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    Where did you get the new cells from? I'm in California.
    Posted via the PriusChat mobile app.
     
  7. Isaac Zachary

    Isaac Zachary Senior Member

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    On eBay. I got 3 for around $100 total with shipping.

    Of the three two had better capacity than the rest of my pack. But one was about the same as my pack.
     
  8. drewbabich

    drewbabich Junior Member

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    Isaac, What method did you use to test your capacity? And more importantly give us an update on how long your rebuild effort lasted in years and miles before you had to repeat the process?

    I have replaced one cell so far and my situation has improved but i have some little trickster cells that were reading 8.05 static volts that must still be junk cause i'm still getting replace hybrid batter error code.

    Shame on me for being lazy and just replacing one cell that was reading 6.73 volts.
     
  9. Isaac Zachary

    Isaac Zachary Senior Member

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    Note: sadly I haven't ever driven my Prius after rebuilding the battery. It needs an engine, it needs a California compliant catalyitc converter (about $2,000 just for the part) and it needs a wheel bearing and windshield. And those are just the parts I know of that it needs. I'm going to sell it as is and forget about getting another car for the moment.

    I used this tester or one just like it: https://www.ebay.com/itm/294924202249?mkevt=1&mkcid=1&mkrid=711-53200-19255-0&campid=5338765313&toolid=20006&customid=16288dbac8f02ebfada9a6d951521953

    And I got a bigger, more powerful resistor to handle the voltage and slow the current to about an hour or two per module (which does mean it will take time to test all. I can't remember exactly the one I got.

    I also got a Tenergy 6 cell NiMH charger. Only charge the cells while they are sandwiched in the battery pack with those long bars. I avoid problems I flipped every other module so all the positive posts and negative posts were on the same side.

    So basically I would charge a module, test it down to the preset voltage of the tester, then charge it back up and move on to the next module. I also did the same with the new modules.

    Once I got all the modules tested I wired them all up in parallel, which was easy to do because I had all the positive posts on one side and all the negative posts on the other. So I took some bare solid wire and just clamped it down across all the positive posts, and did the same with another wire across all the negative posts. Then I put the charger on those and left it for quite a while to balance all the voltages.

    Then I took the best modules and put them in the middle and put them in order so the worst modules were at the ends. I of course flipped the modules back they way they should be and put the bus bars back on and such to put the battery back the way it was suppsed to be.

    I hope that helps!
     
  10. drewbabich

    drewbabich Junior Member

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    Wow that is a lot of work to do to a battery for a car that needs an engine and catalytic converter. Thanks for the link

    You are my hero!