Prius hybrid battery reconditioning

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by zeno, Nov 28, 2021.

  1. zeno

    zeno New Member

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    Hello guys,
    Regarding prius g2 battery reconditioning... maybe you can make me understand:
    if you follow the Prolong instructions for descharging and if you use a grid charger, you should descharge the entire battery (all 28 modules at a time) to 134/101/84V, meaning 4.8V/3.6V/3V per module (0.8V/0.6V/0.5V per Cell).
    If you are discharging individual modules with kind of iMax, the discharge voltage should be 6V per module, meaning 1V per Cell.
    Some posts says that you should never discharge a NiMh cell under 0.8V.
    Can you please advice which is correct?
    Many thanks
     
  2. nancytheprius

    nancytheprius Active Member

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    prolong seems to be pretty successful in restoring some lost capacity. There are a variety of different settings and methods to do the reconditioning, and many posts are contradictory like you noticed. Some people are not comfortable going all the way down to the 84 V. If you are worried about it then maybe play it safe and go down to 134 V each time, but you should be fine to go lower if you have the time.
     
  3. nancytheprius

    nancytheprius Active Member

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    The posting below may help you in deciding what is successful. (I just learned if you hit the little arrow at the top of the quote next to who said it that it will take you to that thread)
     
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  4. nancytheprius

    nancytheprius Active Member

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  5. zeno

    zeno New Member

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    Thx a lot!
     
  6. dolj

    dolj Senior Member

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    ryousideways did a lot of good work and successfully r&r'd his battery (maybe more than once), but since the time he did his work it has been determined that the following:
    ... is not balancing and provides no beneficial purpose, especially for the time you are supposed to take to do it properly. Just forget about this equalizing procedure. You just need to use your charger to charge each module to be +/- 0.1V of each other if they are not. Further, if any particular module will not hold its voltage and diverges from the rest over a period of days, or a week, you need to replace it.
     
  7. Gino Veltri

    Gino Veltri Member

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    Im confused, so many places here say not to discharge below 6 volts per modules. But then i see some other people discharging eventually down to 3 volts. How can this be right? Is that 3 volts per cell?
    I also have 3 different hobby chargers, the cheap imax knockoff is garbage, but this dual port one has preset discharge voltages such that S6 is 4.8 volts. Am i damaging my modules going this low? Its actually produced some good maH numbers but im super confused by this.

    If i want to discharge to 6 volts its listed as S8, but i know there are only 6 cells in each module to Im afraid to use that setting.
    Also what should my capacity cutoff be? Im going with 6.5 just because thats the factory spec for a brand new battery. In theory this shouldnt matter because my modules are older than dirt, right? Theyll never reach close to 6.5 Ah again, correct?
     
  8. Gino Veltri

    Gino Veltri Member

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    Will someone just answer this question? Threads veer off topic faster than my attentio....

    n span
     
  9. dolj

    dolj Senior Member

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    No, 3 V/module or 0.5 V/cell.
    The answer to your question is, 'it depends.'

    It depends on the current used to both charge and discharge. Discharging below 7.2 V per module (1.2 V per cell) and charging above 8.4 V per module (1.4 V per cell) the discharge and charge current should be limited to 0.05C (which is 325 mA (for a 6500 mAh Prius module).

    Secondly, it depends on how bad the module is in the first place as to how high of a current will damage the module. It could be argued that this second consideration is not that important given that if the module is so bad that it will be damaged by charging or discharging, you don't want it anyway and it should be replaced.
     
  10. Gino Veltri

    Gino Veltri Member

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    Welp. I screwed up then, as I discharged as high as 5 amps, down to 4.8 as that what my charger preset as 6S, and charged at 2 amps, up to whatever the charger would go to because there isn’t a clear voltage cutoff for charging on the hobby charger. Many went as high as 9 volts.

    but the numbers I got were promising, increasing capacity with each discharge. I’ve reassembled and haven’t gotten another red triangle but now my voltage differences are as high as .8 sometimes.But this essentially is the difference in final voltages I ended with before having to throw it back in the car for an emergency. I used a 16 (x2) hobby chargers and a multimeter (which weren’t exactly calibrated with one another). I should also add that I never pinpointed the failed module and replaced it. I just cycled each module and was satisfied with the numbers I eventually got back.
    …half assed, I know. So I’m going to keep at it.
    No more red triangle though!

    …voltages in series won’t “balance out” the way they do in parallel, correct? How do you recommend I get all modules to within .05 v of each other?

    how important is the 48 lbs of torque ? A connection is a connection , right?
     
  11. Gino Veltri

    Gino Veltri Member

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  12. Gino Veltri

    Gino Veltri Member

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  13. dolj

    dolj Senior Member

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    Very important and NO. If they are too loose and you might have high resistance, and/or arching, and/or fires. Too tight and you risk breaking off a terminal stud. The trouble is, if you're inexperienced, you cannot know what 48 in-lbs is unless you have used a torque wrench to set that and then use your regular wrench to 'feel' what that torque is.
    Not necessarily. This falls in that 'it depends' category. Seeing as you got your battery together and are driving the car without codes, you got lucky. Your modules were probably not too bad from the outset.
    You use the "Report" button at the bottom left of your post and report the post asking if the moderator would kindly delete it for you.
     
    #13 dolj, Dec 8, 2021
    Last edited: Dec 8, 2021
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  14. Raytheeagle

    Raytheeagle Senior Member

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    Make sure it is 48 INCH lbs of torque too;).
     
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  15. Gino Veltri

    Gino Veltri Member

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    Lol. No torque wrench but I understand 48 INCHES is not a lot and those bolts are fragile
     
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  16. Gino Veltri

    Gino Veltri Member

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    gotcha. And I have experience snapping off the terminal studs so I think I must have a good understanding of the torque needed.
     
  17. Gino Veltri

    Gino Veltri Member

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    Also, how are my voltage differences (1.2 v sometimes) not setting off a red triangle warning? I thought differences that high for a period of time would upset the computer…
    Or did I just get lucky again, my Prius is extremely tolerant of my abuse so I wouldn’t doubt it. Seriously, do these cars ever “die” ? Or is it just one too many high dollar repairs that cause people to scrap the whole car? *knocking on wooden ashtray*
     

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  18. dolj

    dolj Senior Member

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    Check the car while it is running, the voltage delta is probably not that high or for that long a period of time. Just remember, static voltages are not that useful for the most part.
     
  19. Gino Veltri

    Gino Veltri Member

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    I’m only using dr.Prius, so no voltage delta, whatever that is. Isn’t the delta peak the drop in voltage when a battery is full that tells a charger to stop charging?
    Anyway I pulled that battery, as it was my incomplete first attempt at reconditioning, and replaced it with a random donor battery that some kid tried to sell me for 400$, after I reconditioned it and got the voltages within .1 of each other.
     
  20. edthefox5

    edthefox5 Senior Member

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    Delta is the difference in voltage between the packs. Very important. You will get the RTOD on a big delta from an offending module.

    To future lurkers if your not really experienced on cranking down bolts and no torque wrench it may help on this battery to use a 1/4 inch Ratchet. Little harder to mungo a bolt with that wrench.

    If you are inexperienced using a torque wrench practice on tire lugs to hear and feel the tick. .Set it to 48 inch lbs and practice on the tire lug.
    48 ip is not much.
     
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