Prolong balancing - have only 40 hours.

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Joeman200, Apr 12, 2019.

  1. Joeman200

    Joeman200 New Member

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    Hi all, I just installed my prolong harness and am ready to begin balancing. I work shifts and only have about 40 hours of time off.

    I'm wondering what y'alls opinion was on the idea of charging, discharging to the stage 1 volts, charging again, working my shift, discharge 2, charge, working my shift, discharge 3, charge, done. (Compared to having it all done at once)(driving a different car to work and having it sit those 24 hours fully charge)

    Hope this makes sense. Thanks.
     
  2. srellim234

    srellim234 Senior Member

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    I think if you're careful you can probably work out some kind of schedule. Consider using your first 40 free hours to charge and balance the cells with a long "soak" session. Work your shift, making sure the battery remains somewhat full when you get home. Recharge, but not "long soak" it again to top it then perform the first discharge. That will allow you to put the charger back on for 12-18 hours before your next shift. Repeat the process on subsequent free days. As long as you don't allow too much driving between sessions the charge/discharge sessions can be disrupted a little.

    Most important is to make sure you allow enough time after charges to let the batteries cool some before you start the car. Otherwise the battery can overload and fail. I'd plan a 2-3 hour window before starting the car.

    Before you do anything, call Hybrid Automotive and ask for their advice. I'm sure you're not the first customer to face such a time constraint and they are much more knowledgeable than I am.
     
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  3. Raytheeagle

    Raytheeagle Senior Member

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    It isn’t a good idea to interupt the 2 cycle reconditioning process as you won’t see all the complete benefits as you’ll be working the cells out in between;).

    I’d find access to a second car and leave the Prius in the same state so that the process completes uninterrupted.

    Good luck and keep us posted (y).
     
  4. srellim234

    srellim234 Senior Member

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    I agree. It's not a good idea to interrupt things but Joeman200 was looking for a way to fit it into his schedule without using a second car. I was trying to suggest something that might work but I wouldn't try it unless Hybrid Automotive was ok with it.
     
  5. Raytheeagle

    Raytheeagle Senior Member

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    I’d just do a top end balance as that is the only thing that will fit in the window;).

    Unless there is another car, it’s pressing your luck :cool:.

    No whammies hopefully (y).
     
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  6. Joeman200

    Joeman200 New Member

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    To clarify (Sorry I don't type well from my phone), I do have access to a second car, its more of do I need to do each step of the process immediately one after the other, or can the battery sit for 24 hours after each stage?
     
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  7. Raytheeagle

    Raytheeagle Senior Member

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    Sitting is ok:).

    Second cars help a lot ;).

    Recondition away(y).
     
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  8. mjoo

    mjoo Senior Member

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    When I'm doing a Prolong session I'll take the bus to work. Albeit it's only a 4 mile trip. Is Uber/wife available?

    Pixel XL ?
     
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  9. edthefox5

    edthefox5 Senior Member

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    Just do a 30-40 hour unattended charge like Ray said to start off. Let it run. See how it likes it.

    See what that does on my battery it really wakes it up. That will hold you until you can spend a few days to do a full discharge. You did the hard part which is bolting in the harness its not that hard but a pain to get too now time to put it to work.

    Good luck!
     
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  10. srellim234

    srellim234 Senior Member

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    The others are right. Use the second car and let the Prius sit until you can get back and do the next step of the process.

    Another issue to take a look at. Since the Prius is not going to be running and will instead be sitting for an extended period of time, consider putting a battery tender on it to keep the 12v battery in good shape and charged. It would be really frustrating to spend a week+ juggling this process only to find you have a dead 12v when you eventually do get ready to start it again.
     
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  11. edthefox5

    edthefox5 Senior Member

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    Yes good one I do the same charge all battery’s at the same time. Just let them run. Leave them both on
    For 30 hours.
    I recently bought a new 12 volt battery charger with recondition mode I really like it. Citek MUS 4.3
     
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  12. srellim234

    srellim234 Senior Member

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    Deltran 3 amp Battery Tender here. Picked it up at a Costco outlet store for $29.99.
     
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  13. dolj

    dolj Senior Member

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    You can let it sit after each charge stage, but you should put it on to charge immediately after each discharge.
     
  14. Raytheeagle

    Raytheeagle Senior Member

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    I’ll be in this boat next week as I prepare to sell our 2010;).

    So I’ll be discharging when I get home and charging up while away at work:cool:.

    But the next owner will have a fully reconditioned battery along with all the other preventative maintenance performed (y).
     
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  15. Joeman200

    Joeman200 New Member

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    Wanted to post an update. After using the prolong charger/discharger, my battery bars generally stay in the top purple section, I can sit in traffic longer without it draining as fast, and I have noticed a 2mpg improvement (going from a 47.5 to 49.5 average). I was able to do the whole process even with my weird schedule (although I did have to stay up to 3am one night). On that note, that is one hard thing about this process, the time it took to discharge/charge didn't follow the same pattern. What took hours to do one time (say discharging at 75w) took only an hour the next time. Heaven forbid they are left unattended though, once the wattage drops, boy it drops fast!
     
  16. TMR-JWAP

    TMR-JWAP Senior Member

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    Here's how I look at it. If you're limited on time, I feel your better off doing multiple discharge/charge cycles using the first voltage setpoint (134v iirc). Here's why IMHO:

    I believe we have proven over and over that deep cycling an NiMH battery will restore lost capacity. I've put plenty of postings up related to that.

    Some easy to work with numbers:
    A standard D cell battery is 1.5 volts and 8000 mAh capacity.
    A standard C cell battery is 1.5 volts and 4000 mAh capacity
    A standard AA cell battery is 1.5 volts and 2000 mAh capacity
    A standard AAA cell battery is 1.5 volts and 1000 mAh capacity

    Lets pretend all these batteries are 7.2 volts instead of 1.5, but everything else is the same.

    To make this easy to understand, think of a BRAND NEW HV battery as 28 "D" cell batteries connected in series (@ 7.2 volts each = 202 volts). Your HV battery, after many years of successful service, is no longer 28 "D" cell batteries, but now more similar to being 5 ""D" cells, 5 "C" cells, 9 "AA" cells and 9 "AAA" cells. All these are still equal voltage so overall we're still at 202 volts.

    The performance of your HV battery is now completely limited by the individual battery module that has the lowest mAh capacity. That would be one of the AAA batteries.

    When the prolong is connected, and the discharge starts, it has no idea of voltages or capacities of individual modules. It only knows the overall combined voltage. So we start our discharge with a target value of 134 volts. Let's assume the discharge rate starts at 1 amp. That's 1000 mA.

    Are all 28 modules going to deplete at the same rate? ABSOLUTELY. They're connected in series. So after 1 hour at 1000mA, we've removed 1000mAh from EACH module. Guess what? Those 9 AAA capacity modules have given it all they have and their voltage drops rapidly toward 0, the other 19 modules may drop a couple tenths of a volt each and we hit the 134 volt setpoint. Where are the other 19 modules? The others are still at the 7.2 plateau or higher. This discharge has done nothing for them in terms of deep cycling, especially the D cell modules, but it doesn't matter. Those 19 modules were having no effect on how limited your HV battery was. It was the 9 AAA modules that were ruining your day.

    Now you do charge cycle. By the time it's finished, all 28 modules actually get overcharged to the point where the energy is converted into heat instead of being stored. All 28 modules are fully charged to what each can handle now, but they're still not equal. If all goes as planned, those 9 AAA modules have become closer to AA modules in capacity, so overall HV Battery performance goes up. Doing the 134 volt setpoint will work fine for bringing the weakest, most limiting modules closer to the good AA modules. That's the end goal, to have them all close in capacity.

    Each time you go to a lower voltage setpoint (134, 84 and 17 I believe), you're getting more and more of the modules to that "fully depleted zero voltage" condition. So at the 84v setpoint, all the modules that were originally AAA and AA are now the ones to get to a deep discharge state and the C and D modules are still at the 7.2 v plateau. When charged, now those 18 are closer to the C capacity. and so on and so on...obviously, the 28 modules are not going to fall into neat little AAA, AA, C, D values, but hopefully it helped explain everything.

    So, when you really think about it, the Prolong sequence really focuses all it's energy into improving the capacity of weakest modules and potentially does nothing for the strongest modules. And that makes sense, since it's the weakest modules that are the limiting factor for HV battery performance.
     
    #16 TMR-JWAP, May 23, 2019
    Last edited: May 24, 2019
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