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Quantitative Results of Grid Charge/Discharge

Discussion in 'Gen 2 Prius Technical Discussion' started by S Keith, Dec 6, 2015.

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  1. theGlass

    theGlass Junior Member

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    Hey all,
    Finally reached the point with my 2005 prius that I'm commenting here. 20 months ago had the battery on my car run into trouble(239k miles and 9 years)- read around a bit and decided to go for a rebuilt battery from Greentec Auto. Swapped it out, it worked fine until this week, 2 months after the warranty expired, natch (33k miles on the battery). I'm in a tougher financial situation now so I spent yesterday reading up on stuff all over the web but mostly came here. Greatly enjoyed the analysis and comments of S Keith and jeff652, so I ordered a HA Prolong this morning. I'm sure I can handle the discharge stuff on my own. I'll report on how things go.

    The reason I'm broke at the moment is that I'm in the middle of starting my own lithium air battery company. What incredible irony!
     
    #81 theGlass, Apr 14, 2016
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  2. S Keith

    S Keith Senior Member

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    Before you embark on the full reconditioning process, I recommend you investigate the failure. Unfortunately, due to the fairly uniform deterioration of the prismatic modules, when they go, they go hard. Catching them at the first signs of trouble, like accelerated gauge activity or reduced mileage greatly improves the chances of avoiding module replacement.

    If you didn't order the discharger, you will need to cobble something together to either directly connect to the pack or to the connector. If you didn't order the discharge ready version, I don't believe you have the option of connecting to the harness as it has a diode in the harness to prevent backflow to the charger. If you intend to discharge, the perceived savings from not ordering the reconditioning package are false economy.

    Since accessing the battery for install fully exposes the pack, I vigorously recommend you remove the cover and record all the resting voltages of all modules at least 10 hours after they have been sitting. You should obviously exercise all safety precautions against high voltage exposure. Completely removing the bus bars on the front of the pack disarms it to the point of having 13 independent ~14.4V batteries and two 7.2V batteries (disconnected at the safety plug wires). This would also be a good time to inspect your sensing wires and bus bars for corrosion.

    I would also recommend a 24 hour rest between charging and discharging with additional voltage readings at the end. Waiting 24 hours can give some insight into bad modules as they will drop notably below the others.

    I think you need to adjust your expectations to where you will NEED to replace one or more modules, particularly in a Greentec pack. We don't know how much mixing and matching has been done. It would be a good idea to document the first four digits and last digit of each module serial number for comparison.

    The HA grid charger is an excellent tool for top balancing the pack after module replacement and for periodic battery maintenance.

    Good luck,

    Steve
     
    #82 S Keith, Apr 14, 2016
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  3. theGlass

    theGlass Junior Member

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    Hi Steve,
    Thanks for the advice. I'll check the module voltages and serial numbers. One thing I haven't come across in my readings yesterday is a best practice procedure for disconnecting the busbar, other than the obvious advice of using insulating gloves and taped up tools. I have another set of wheels, so I am not opposed to spending another week to make sure the job's done right (or better) than a quick fix.
     
    #83 theGlass, Apr 14, 2016
  4. S Keith

    S Keith Senior Member

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    1. Carefully remove the black protective covers with one hand. A small flat blade screwdriver can help you disengaged the few clips along the top.
    2. Spin off the nuts with a cordless impact driver, 8mm socket.
    3. Carefully slide the bus bars off the terminals.
    Until all nuts are removed AND all bus bars are off the terminals, a shock hazard exists. For me, I minimize risk by only touching the bus bars with 1 hand while removing them. This limits the total voltage to which I can be exposed to "painful" vs. lethal. :)

    The more time you spend on this, the better your results.
     
    #84 S Keith, Apr 14, 2016
  5. theGlass

    theGlass Junior Member

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    the numbers I got for the modules(measuring front of pack, passenger side to driver's): 16.12, 16.19, 16.17, 16.18, 16.16, 14.86, 16.16, 16.18, 16.17, 16.17, 16.18, 16.18, 16.19, 16.14V. Techstream said 6 and 7 were giving errors. 6 is clearly low. Battery in garage, 12 Celsius, after sitting overnight. Will get serial numbers next.

    Thanks again. I am trying to balance time vs results. I do not have a ton of time available, but I have more time than money at the moment. I would like to do a solid job on this but not spend 2 weeks on it. I would also like to not cut corners or time on a "partially assed" job.
     
    #85 theGlass, Apr 14, 2016
    Last edited by a moderator: Apr 15, 2016
  6. S Keith

    S Keith Senior Member

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    What you're measuring are block voltages, not individual modules, but that gives confirmation of the Techstream results. You will need to remove the plastic covers off the pack side of the pack. This is safest with the front bus bars removed, but if you're careful, you can safely measure all 28.

    The 1.3V disparity screams a failed cell in one module.

    If Techstream is showing issues with 7, it may be that it will whow good resting voltages, but it may have large swings due to reduced capacity or high internal resistance. I would encourage you to consider a load test to investigate. The $25 harbor freight 100A 12V load tester is an excellent option.

    Under a week and about 4-5 hours of touch time on your part is a rough estimate.
     
    #86 S Keith, Apr 14, 2016
  7. theGlass

    theGlass Junior Member

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    $25!?!?! Stop the madness! I don't think I could build one that cheap!

    module number, serial number (all started with 27XHEA), open circuit voltage. #11 is the only one (at the moment) that looks verklempt.
    1 03307Y 7.97
    2 03278Y 8.06
    3 03274Y 8.05
    4 03302Y 8.06
    5 03303Y 8.05
    6 03374Y 8.04
    7 03305Y 8.06
    8 03306Y 8.05
    9 03263Y 8.04
    10 03264Y 8.05
    11 03261Y 6.75
    12 03262Y 8.04
    13 03256Y 8.04
    14 03238Y 8.05
    15 03241Y 8.05
    16 03239Y 8.06
    17 03265Y 8.05
    18 03267Y 8.05
    19 03252Y 8.04
    20 03253Y 8.05
    21 03254Y 8.07
    22 03255Y 8.05
    23 03257Y 8.05
    24 03249Y 8.06
    25 03260Y 8.08
    26 03248Y 8.05
    27 03520Y 8.06
    28 03251Y 7.95

    Maybe I start with re-habilitating that one.
     
    #87 theGlass, Apr 14, 2016
  8. S Keith

    S Keith Senior Member

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    IMHO, #11 is a monumental waste of time. You will get nothing out of it. I have a several modules that started at < 7.2V, and not a single one was recoverable.

    Odd that you basically have a reconditioned pack filled with what appears to be the original modules all made on my wife's 36 birthday and the same batch.

    I would....
    1. Grid charge it for 24 hours
    2. wait 24 hours
    3. record resting voltages
    4. load test each module for 15 seconds recording voltage at 15 seconds immediately before terminating discharge.
    5. discharge pack to 84V w/2X 25W bulbs in series (optional to use up to 2X 200W above 185V).
    6. grid charge for 24 hours
    7. replace #11 and any modules that failed step 4 with fully charged good module(s)
    8. Maybe grid charge for 4 hours for good measure.. to make sure everything is fully topped off.
    9. Run discharge test in my sig logging with techstream for exact numbers.
     
    #88 S Keith, Apr 15, 2016
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  9. theGlass

    theGlass Junior Member

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    Thanks. Copy that. Only error I can see above is that clearly your wife is 29.
     
    #89 theGlass, Apr 15, 2016
  10. S Keith

    S Keith Senior Member

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    Good catch. You are correct.
     
    #90 S Keith, Apr 15, 2016
  11. MTL_hihy

    MTL_hihy Active Member

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    In case others find this later and want to build their own load tester this is how I did mine and it worked very well to find the bad one(s). Make sure to hook up both the high and low beams, use good connectors/wire and the longer you run the test the better (bigger voltage drop, 5 mins max)

    Gen II Prius Individual Battery Module Replacement | Page 13 | PriusChat

    Also as suggested above you need to have a mini VCI setup to be able to watch the voltages under load while driving the vehicle since bad modules will show up as the highest voltages when in charging mode (engine running) and then quickly drop to the lowest voltages when being discharged (EV mode).
     
    #91 MTL_hihy, Apr 18, 2016
  12. jeff652

    jeff652 Senior Member

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    Please do let us know how things turn out. We have hundreds of people who have gone through this process and been very pleased with the end results. I'm hoping you will end up as another :)
     
    #92 jeff652, Apr 18, 2016
  13. MTL_hihy

    MTL_hihy Active Member

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    Definitely will Jeff, very optimistic given the comments/results seen by others.

    So far will vouch for great service with HA on getting out the charger quickly, just need to get to the border to pick it up.
     
    #93 MTL_hihy, Apr 19, 2016
  14. snijd

    snijd DIY or die

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    Just completed two cycles with the HA charger and the light bulb discharger on our 2006 car, which has about 70,000 mi. I'm seeing mpg's similar to when we got the car, in 2008. Discharged a little farther than intended on the second discharge, but it charged right back up to 240v. Jeff has suggested a third cycle, but I ran out of time to continue, at the moment. Very pleased with the results, so far. BTW, there were no indications of any problems with the battery, so this is simply preventative/routine maintenance. It seemed prudent, with a 10-year-old battery.
     
    #94 snijd, Apr 21, 2016
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  15. Jimbo913

    Jimbo913 Junior Member

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    So how long did the entire process take for two discharge cycles and did you use the HA charge/discharge protocol or another?

    You mention that it was only routine or PM, but also mention that MPG's are back, so what were you getting MPG's before and then after?

    I am getting ready to order an HA kit, but trying to decide on the light bulb and intelligent charger. Looked around on here for a discount on the HA, but guessing there is none for members?

    BTW - I have a 2006 with 115K miles and getting 51 mpg consistently. The car is new to me, but it seems like the battery level drops fast on the info screen when headlights or A/C are on, but then it charges back to Green fast. I am pretty sure that the usable range is limited and can be improved. Hoping to get it done in the next couple months, but also want to avoid doing it the "hot" days of summer.
     
    #95 Jimbo913, Apr 25, 2016
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  16. S Keith

    S Keith Senior Member

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    This is not something to be rushed, and subsequent cycles can be done at other times. You realistically need up to 72 hours to thoroughly charge/discharge/charge in a conservative fashion. I have several shortcuts depending on circumstances that can expedite without compromising safety. I recently outlined one in the discharge test thread (in my sig), were you can confirm your state of health. Ambient temperature needs to be above 70°F to be effective.

    IMHO, grid charging without discharging is only useful for packs being nursed to their end. You need the ability to discharge to conduct maintenance on a healthy pack.
     
    #96 S Keith, Apr 25, 2016
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  17. jeff652

    jeff652 Senior Member

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    Two cycles can be done in a single weekend, if started Friday evening and finished early Monday morning. Three cycles take three days, etc. Give us a call and Carl can talk you through the process. (800) 589-0730. Tell him Jeff said you can have free shipping since you are a PriusChat member ;-)
     
    #97 jeff652, Apr 25, 2016
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  18. Jimbo913

    Jimbo913 Junior Member

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    I agree on the grid charging without discharging and I wont try to rush it I am just making sure what I am getting into. I guess the discharge is the tough one which you would ideally want to occur during awake hours so it is easier to monitor. I guess you can stop and resume though - correct?

    Waiting patiently for the 4/28 update
    : ) and really appreciate you sharing your knowledge.
     
    #98 Jimbo913, Apr 27, 2016
  19. S Keith

    S Keith Senior Member

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    To be frank, I have unintentionally run packs down to 1.2-10.0V w/25W bulbs with no measurable issues. I'm of the opinion that once the minimum wattage bulbs are in, one is extracting so little capacity at such low current, the potential for damage is extremely low. I like to do the switch over from the highest watt bulbs to the 25W right before bed. Sometimes I overshoot a little by morning, sometimes I still need more time. I really don't sweat it if I go too far.

    For testing/reporting purposes, I make the extra effort to hit the target voltages. For personal use or more casual efforts, I have a pretty wide "good enough" zone for the 25W discharge endpoint.

    And yes, you can stop and resume. NOTE: voltage will frequently rebound significantly if left for a significant period of time. Don't worry about this, and don't repeatedly discharge down to the target voltage. There is no value in doing so.

    I have confirmed the re-test appointment for tomorrow. I will post results tomorrow evening.

    Steve
     
    #99 S Keith, Apr 27, 2016
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  20. MTL_hihy

    MTL_hihy Active Member

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    Steve, much appreciated.

    So if I understand right there's no harm in overshooting the voltage drawdown when using the lowest value load (ie 25W)? So for instance let's say it wasn't quite done in morning and I went to work then came back at night and had overshot that would be fine? Batteries are working fine now so just don't want to cause any damage by accident.
     
    #100 MTL_hihy, Apr 28, 2016
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