Current State of the Art in Battery Balancers?

Discussion in 'Gen 3 Prius Main Forum' started by jimolson, Jun 21, 2025.

  1. Hayslayer

    Hayslayer Member

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    Just in case anyone is looking, the G9510-47063 hybrid battery (2010-2011 probably others gen3 prius) is now available for $1535 new. The 28 modules inside are 100% interchangeable with the Gen 2. You can essentially have a brand new Gen 2 battery, built with the latest Gen modules if you're able to DIY the module swap. You'd probably want to buy a new sensor harness also for about $60.
     
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  2. PriusTech

    PriusTech Member

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    I'm still learning how to identify bad modules.

    I cleared the P0A80 with a generic code reader and by disconnecting the 12V small battery, it keeps coming back

    The Delta SOC was 40

    All three cycles the battery was charged to 237V - 238V

    I had the metal cover off and a box house fan on top running on medium for the entire process

    The before charge-discharge-balance volt test showed a .05V difference between high and low modules. (Picture on my post #36 above)

    The after charge volt test also shows a .05V diff between high and low modules. (pic attached)

    Haven't done a volt test after discharge, will do so. So any module that is lower than .03V from the highest module is suspect bad?
     

    Attached Files:

  3. Brian1954

    Brian1954 Senior Member

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    How many hours did you charge the hybrid battery to achieve the 238v?

    I do not think you charged the battery long enough to top balance the complete battery pack. Try charging the battery for 24 hours. The battery voltage should go to 243v to 245v and then it will decrease a few volts. Then, you know you have achieved balancing of all the cells in the battery pack. If you do a top balance of the battery correctly, the DELTA SOC should come down.

    Read the online Prolong reconditioning instruction about top balancing the battery pack.
     
    #43 Brian1954, Jul 29, 2025 at 10:02 AM
    Last edited: Jul 29, 2025 at 10:08 AM
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  4. PriusTech

    PriusTech Member

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    I think you may be right, Prolong says for the last topping and balancing it's around 24 hrs and up to 48 hrs. So on the last cycle it was 24 hrs, and it went from 125V to 238V, but never got higher. Between that and not finding the bad cells to replace is probably the issue
     
  5. Hayslayer

    Hayslayer Member

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    The Prolong WILL NOT cure a failing module. It may hide it temporarily, but it will never cure it. Voltage readings, without a load test can be deceptive.
     
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  6. PriusTech

    PriusTech Member

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    Yeah, there is a couple of YouTube vids where they are taking timed voltage readings as they're doing a load test
     
  7. Carall

    Carall Member

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    You are in a situation that has already been discussed here on the forum years ego. The Hybrid Automotive's method of discharging the entire battery to 84 volts will not fix the P0A80 code. There are several weak cells in a few modules in your battery that won't recover until you discharge the whole battery below 84 volts. The battery with 125k miles is unlikely to have dead modules that can no longer be recovered. A situation with 3 bad modules, with code P0A80, occur closer to 200k miles on the 2010 prius.
    I would do one cycle by discharging the entire battery to 3-5 volts and then discharging it on the car to 40% and checking the voltage of each module after 10 minutes if the voltage does not vary more than 0.03 volts. The discharger can be assembled, as in my photo, from 40-watt light bulbs.

    20250719_231053.jpg
     
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  8. PriusTech

    PriusTech Member

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    Thanks for your help, I should be on Priuschat more often but my Prius hasn't had too many problems until now.

    So discharge to 3-5 volts total for the entire pack, using 2) 40 watt bulbs and a voltmeter, full charge/balance with the Prolong charger, then discharge it on the car, by driving it, and monitoring with the Dr Prius app to 40%, or using the Prolong discharger to 101V (which is about 40%?)

    Do you ever do the balance where all the modules are turned to face the same way and a wire is run across all the + and all the - terminals (in parallel) and let sit overnight? Or do you prefer the Prolong balance method?

    When this is all done I'm going to do a full right up on the process from start to finish, if I can't find that has already been done. There's so much conflicting information.
     
  9. Carall

    Carall Member

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    Just discharge to 40% with the Dr. prius app, as it is done during the battery test.

    Balancing modules by connecting them in parallel looks nice until you install them in the car. The Prolong balance method balances all modules by capacity when all modules are original.

    There are several processes. The process for this Frankenstein battery will require all existing methods to bring it back to life.
    Hybrid battery - how bout just changing bad cells without "reconditioning"? | Page 2 | PriusChat
     
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