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Is this battery reconditioned enough and ready for reinstallation?

Discussion in 'Gen 2 Prius Technical Discussion' started by bbellgrl, Jul 11, 2024.

  1. bbellgrl

    bbellgrl Junior Member

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    I've finally gotten my battery reconditioned after upgrading my wires and making a few change. My previous challenges are outlined in this thread.

    After 2 weeks of reconditioning with the EV-Peak BGUAD CQ3 Multi Charger (discharge/charge cycles with discharge at 1 amp/6v and charge at 3 amps with capacity cutoff set to 7500 mAh) I have hit charge capacity on 24 of my 28 cells. The remaining 4 are all above 7000. Most discharge capacities are in the 4000 range, with a couple over 5000. I've listed my results below with some color coding (red isn't bad, just lower than peak). Is this thing ready for rebalancing and reinstallation, or should I keep going unti i increase the discharge capacity on all of them? Is it okay if some of the cells don't hit charge capacity of 7500? Do they need to be replaced? Higher voltage cells are the ones that just finished a cycle. The others haven't been touched for a week as I was out of town.

    How is this looking to wrap things up and reinstall?

    Screen Shot 2024-07-11 at 11.04.22 AM.png
     
    #1 bbellgrl, Jul 11, 2024
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  2. BrokenPipe

    BrokenPipe Junior Member

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    Yes it should be good enough. However, hitting capacity cutoff during a charge doesn't tell anything about the module health. There are all sorts of reasons that could influence why a module might hit capacity cutoff such as temperature, pressure, internal resistance etc. The best indicator of module health is checking, how much current can be discharged from it. Also
    the above table shows "Max Dsc"(discharge). It's probably better to look at the most recent discharge, rather than max discharge. Rather look at the trend If a module keeps getting better or worse in terms of discharge as it's cycled on the hobby chager.

    Finally if you are going to the trouble of removing the battery from the car, and doing all this work testing, it makes more sense to get rid of atleast 5 to 10 of the worst ones and replace with better ones. Also clean or replace all the busbars and nuts while doing this.
     
    #2 BrokenPipe, Jul 13, 2024
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  3. dolj

    dolj Senior Member

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    The problem with using the capacity cutoff feature is you never top-balance the module.

    After you've achieved the capacity cutoff, you need to turn the capacity cutoff off and set the charger to charge infinitely at 325 mA while monitoring the voltage. Allow the voltage to increase until, over a period of 4 to 6 hours, the voltage no longer increases. To save time, you could connect two modules in series and charge two at a time.
     
    #3 dolj, Jul 14, 2024
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  4. bbellgrl

    bbellgrl Junior Member

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    Thanks everyone. I've finished reconditioning all the cells. Every cell discharged above 5,000 mAh except one subborn cell that cannot discharge above 4300 mAh, and has a slightly lower charge capacity. I'm looking at buying a few reconditioned cells, but even ones on eBay say they are guaranteed to have a capacity of at least 3.5 amp hours, but mine is better than that. how bad would it be if I just kept the lone under-performing (only slightly so) cell in the pack without replacing it?
     
    #4 bbellgrl, Jul 25, 2024
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