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Tell me if I’m doing this right. Or wrong!

Discussion in 'Gen 2 Prius Main Forum' started by HerbMPG, Sep 26, 2018.

  1. HerbMPG

    HerbMPG Junior Member

    Joined:
    Nov 14, 2017
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    Location:
    Decatur GA
    Vehicle:
    2016 Prius
    Model:
    Four
    After tinkering around with some other processes, I’m trying this to save time:

    Leave battery in clamp
    Discharge each battery to 6v using two 55w 12v bulbs (not sure but assume this is 5-10 amps)
    After cooling, charge each battery using Tenergy TB6B (5A)
    Each step note time and voltage. If any discharge/charge too fast, I’ll replace (with new modules?)
    When done, discharge each battery to 8(haven’t done this yet)

    Am I discharging too fast? Charging too fast? Can I safely use new modules (already purchased)

    2006 Prius, 125,000 miles. No codes, but Battery has been discharging very quickly, especially when cold
    There was corrosion on nuts, but not too bad
    Tried to follow guidelines (remove bus bars, etc)
    Preliminary tests did not reveal any big differences (<0.1v after 4 minute test)
    I tried using discharge function on tenergy, but it’s too slow
    Considered putting them in parallel, but have read this can be problematic
    Fast discharge requires constant attention. One module got down below 1v when I left it too long
    Also, I probably skewed my fast discharge times when tinkering on some of the modules

    Lastly, many of you have excellent information, but it doesn’t always agree. It really takes a lot of time to find the best info. And for me, who doesn’t want to buy $400+ of equipment, it’s harder. Oh well, it’s the nature of life...
     
    #1 HerbMPG, Sep 26, 2018
  2. PriusCamper

    PriusCamper Senior Member

    Joined:
    Mar 3, 2012
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    4,430
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    Location:
    Pacific Northwest, USA
    Vehicle:
    2007 Prius
    Model:
    Two
    Everything looks relatively good in what you're saying here... I'm not familiar with Tenergy TB6B but you need to make sure charge settings are specific to NiMH battery and that the amps on the charger are fluctuating based on how that battery is receiving the charge (smart charger).

    I usually charge at 4.4 amps and my friend doesn't ever charge more than 3 amps, but 5 amps or less is probably fine. The hybrid pack has a 120 amp fuse and 120 amps divided by 28 modules is 4.2 amps per module, but smart chargers dial back the amps based on how the battery is handling the charge so a tiny bit more amps won't be too big of a deal. Of course NiMH don't like fast charges in general, but if the charger setting is specific to NiMH that concern is probably accounted for.

    I'd recommend against replacing any module until you absolutely have to though. The longer you can keep complete set of 28 modules intact the less hassle. Matching random replacement modules to a pack is problematic and should be avoided.

    Another thought is once you get below 6 volts drop back to just using one headlight bulb instead of 2, so you don't have a problem with module falling off a cliff to 1 volt as fast. This is what Prolong does with their lowest priced discharge system where you change bulbs/ wattage as you get to lowest charge.

    Also to state the obvious, you do 3 or 4 rounds of discharge with each round discharging to a greater depth so as to allow the re-conditioning to happen gradually so you aren't degrading the number of charge cycles/lifespan of the battery. But yes, accidents happen and I've sprinted out the door to disconnect a module more than once when the light got super dim.
     
    #2 PriusCamper, Sep 26, 2018
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