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Charging profile difference, Lead Acid vs. NiMH?

Discussion in 'Gen 2 Prius Main Forum' started by George W, Feb 7, 2020.

  1. George W

    George W Active Member

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    I was wondering if anyone knew what the difference is, in the charging profiles from standard AGM batts, to NiMH ?

    In shopping for a charger to recondition my modules, the products advertise multiple charging modes. Are the battery chemistries so different that selecting the wrong type would damage the module being charged? Thanks.
     
    #1 George W, Feb 7, 2020
  2. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    In a nutshell, yes. You can cause problems ranging from reduced battery life to outright fire and explosion risk if you don't match your charger to your battery chemistry.

    You can get away with a bit here and there, but if you don't really, REALLY know what you're doing? Get the right charger and sleep well at night.
     
    #2 Leadfoot J. McCoalroller, Feb 7, 2020
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  3. PriusCamper

    PriusCamper Senior Member

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    I've not seen any tests regarding damage caused using the wrong charging algorithm... And if you stay under the 1/4 amp charge rate like some of the cheapest grid chargers without specific algorithm included you should be ok. But if you want to charge as quickly and efficiently as possible, it's definitely something you don't wan to to overlook.
     
    #3 PriusCamper, Feb 7, 2020
  4. George W

    George W Active Member

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    I see videos of Prius owners charging with right and wrong equipment. It made me wonder if the charging profile really mattered.

    I have only a ctek 12V (4 amp) charger. It's not quite a match for reconditioning 2 modules tied together. I do have a calibrated, 200mA shunt from a solar circuit I could use for s-l-o-w discharge purposes.

    I'm not interested in fast-charge conditioning. I will do 1 or 2 modules at a time until I find that dead Prius for cheap.

    Thank you, and take care
     
    #4 George W, Feb 7, 2020
  5. PriusCamper

    PriusCamper Senior Member

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    While that might work, the consequences of it becoming a problem could get really expensive and make it seem like an unwarranted risk... And it's going to take a really long time with even the fastest Hobby charger. Here's the best price for one on ebay that's only $33: SkyRC iMAX B6DC V2 Battery Balance Charger Discharger Dual Power DC/DC LiPo pb | eBay
     
    #5 PriusCamper, Feb 7, 2020
  6. George W

    George W Active Member

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    Thank you for that purchase reference. That looks like a good solution. Being that curious individual that I am. I'm going to run a test on one pair of modules with what I have.

    In Reading other YouTuber suggestions. I've learned individual prizmatics shouldn't be discharged any lower than 6 volts. I connected 2 in series, and loaded them with my solar shunt (200mA). I'm monitoring the voltage drop every 15 minutes until I figured out a general rate of discharge. . After almost eight hours the 2 modules were reading 11 volts. I disconnected them. After 3 hours of rest, the final voltage on each Prismatic was 5.9V.

    I connected the CTEK(MUS 4.3) selecting Recondition mode. After about 10 hours the green light came on, and I let the batteries rest for 3 hours.

    The series-connected voltage was 15.6V. I compared this to the voltage of the cylindrical modules I received from 2K 1 toaster. All of his measured around 15. 8 to 15.9V out of the box.

    Individually each Prismatic read exactly the same, 7.78V. I don't think this is a bad initial result, So I'm going to repeat the cycle 3 more times.

    For the second go-around. I'm actually timing the discharge / charge so I can verify (with Math) the values my HFT meter is showing.
     
    #6 George W, Feb 8, 2020
  7. PriusCamper

    PriusCamper Senior Member

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    For starters, you aren't giving these batteries anything near a full charge with the system you're using, so there's no way you're going to get accurate self-discharge and load test data, nor will you be able to charge each cell in a module to the point that all cells are balanced / of an equal voltage. ----> You have to give the batteries a full charge to do that <-----

    As for discharging, only person I know who only goes down to 6volts when testing and reconditioning has $30K in lab grade testing equipment and can make highly precise charge and discharge measurements to be certain reconditioning is completed thoroughly enough... The rest of us need to do three discharges after full recharges, with each discharge going lower and lower. Both myself and Hybrid Automotive do it as (5.5v, 3.5v, 1.5v) and only recently did Hybrid Automotive decide 1v discharge safer than a 0.6v discharge.

    But these batteries are tough, I've seen them discharge down to 0v for long per and bounce back up to almost 6v in a matter of minutes, so I think that's where all the confusion is about discharge voltages.

    Let me know if I can hep you further...
     
    #7 PriusCamper, Feb 8, 2020
    Last edited: Feb 8, 2020
  8. George W

    George W Active Member

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    My goal here is to try and locate the modules which created the red triangle. Because I don't have the necessary equipment for proper reconditioning, I thought comparing cycling times might weed them out. In the meantime, I'm recording the numbers while waiting for the charger to arrive.
     
    #8 George W, Feb 9, 2020
  9. PriusCamper

    PriusCamper Senior Member

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    Load testing is the easiest and least expensive way to do that... If you have regular halogen headlight bulbs, you want to hook up one of those bulbs to a module for two minutes and watch how much the voltage drops. The bad module will lose more voltage than the other modules. Hybrid Automotive sells load testing equipment, which is overpriced and not needed. But their instructions on how to do it are very thorough: Prolong® Battery Module Load Tester User Guide
     
    #9 PriusCamper, Feb 9, 2020
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  10. George W

    George W Active Member

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    The item arrived yesterday, and then I discovered the DC power supply is not included. When I wanted to contact the seller to purchase one, eBay says their server is down-no communicating with the seller just yet I guess this is why the price was good.

    Then I went on Amazon, and see the dual-power version of this item for $50, and it comers with a power cord and battery adapters.

    Frustrating.
     
    #10 George W, Feb 14, 2020
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