Looking for basic load-testing of prizmatic cells.

Discussion in 'Gen 2 Prius Main Forum' started by George W, Nov 7, 2019.

  1. George W

    George W Active Member

    Joined:
    Mar 12, 2018
    547
    292
    1
    Location:
    San Antonio
    Vehicle:
    2008 Prius
    Model:
    Touring
    I switched over my 2008 Touring from OEM cells to Cylinder cells, marketed by NewPriusBatteries . Since the prizmatic batteries are nominal 7.2 Volts, I was curious what the best 'load' would be for the reconditioning process.

    Headlight lamps don't make sense to me, since they are a higher voltage than the source battery. Does anyone think that a 6V 'Lantern' type bulb would make a reliable, steady resistance for a 7 V source? Thank you.
     
  2. PriusCamper

    PriusCamper Senior Member

    Joined:
    Mar 3, 2012
    3,586
    1,305
    0
    Location:
    Pacific Northwest, USA
    Vehicle:
    2007 Prius
    Model:
    Two
    Well, these batteries are still so new the reconditioning conversation hasn't really even begun... But in general when I've done reconditioning on Prius batteries 6v is the behavior of the batteries once most of the discharge is done. Even after draining them down to 0.6v they will quickly bounce back into the 6v range. Because of this I thought about buying 6v bulbs for a more thorough discharge, but unlike 12v bulbs, 6v are very rare these days and way, way more expensive than 12v bulbs, which can be found for $2 each.

    Main problem with using bulbs is there resistance isn't fixed and depends on the temperature of the filament. I use them to get the bulk of the charge out of a module, then I use the 10w resister in the charger to do the last bit of it. @Britprius and others say that this method is a good cheat to speed things up, but in general, best results come from a stable discharge of 250ma, which can take an eternity.

    Lastly, the prizmatic batteries are of an identical charge and capacity as standard Prius packs, just configured differently, so I'm not sure why you're saying 7.2v instead of 8.2v?
     
    NortTexSalv04Prius likes this.
  3. Skibob

    Skibob Senior Member

    Joined:
    Sep 14, 2018
    2,715
    1,385
    0
    Location:
    Northern California
    Vehicle:
    2006 Prius
    Model:
    N/A
    Your talking about rejuvenating your old batteries to resell they, right?
     
  4. George W

    George W Active Member

    Joined:
    Mar 12, 2018
    547
    292
    1
    Location:
    San Antonio
    Vehicle:
    2008 Prius
    Model:
    Touring
    Not necessarily to resell. If I can recondition my old Prius batteries, it raises the possibility of getting another Gen 2 cheap.
     
  5. George W

    George W Active Member

    Joined:
    Mar 12, 2018
    547
    292
    1
    Location:
    San Antonio
    Vehicle:
    2008 Prius
    Model:
    Touring
    Sorry, that was a finger-slip. In solar power renewables, a common practice is to use a calibrated shunt in series with the meter to get a highly accurate power measurement. 100mA and 500mA shunts are typical. It sounds like your 10W is the best method for these low voltages. Thank you.
     
  6. PriusCamper

    PriusCamper Senior Member

    Joined:
    Mar 3, 2012
    3,586
    1,305
    0
    Location:
    Pacific Northwest, USA
    Vehicle:
    2007 Prius
    Model:
    Two
    When you say "shunt" is that the same thing as a resistor, just more precise?
     
  7. George W

    George W Active Member

    Joined:
    Mar 12, 2018
    547
    292
    1
    Location:
    San Antonio
    Vehicle:
    2008 Prius
    Model:
    Touring
    Yes, in a very specific mppt charging for 12V, 24V, or 48V solar renewables. allows that fixed resistance to track real power in and out of a battery bank.
     
    PriusCamper likes this.
  8. Skibob

    Skibob Senior Member

    Joined:
    Sep 14, 2018
    2,715
    1,385
    0
    Location:
    Northern California
    Vehicle:
    2006 Prius
    Model:
    N/A
    Wouldn’t you be better off getting a hobby charger and doing it that way? Then you could match outputs.

    Gen II Prius Individual Battery Module Replacement | PriusChat
     
  9. George W

    George W Active Member

    Joined:
    Mar 12, 2018
    547
    292
    1
    Location:
    San Antonio
    Vehicle:
    2008 Prius
    Model:
    Touring
    Maybe, but I don't know enough about hobby chargers. I'm not getting into the business of reconditioning modules, I just want to revive the weak modules from my old pack. If a hobby charger will help me do that then I'd like to know which one has a charge / discharge cycle to accomplish this.

    Quite frankly I'm excited about the prospect. After getting ripped off by a hybrid repair shop to the tune of $2,600, I wouldn't mind finding a second Prius for cheap and putting a good pack in it
     
  10. Skibob

    Skibob Senior Member

    Joined:
    Sep 14, 2018
    2,715
    1,385
    0
    Location:
    Northern California
    Vehicle:
    2006 Prius
    Model:
    N/A
  11. PriusCamper

    PriusCamper Senior Member

    Joined:
    Mar 3, 2012
    3,586
    1,305
    0
    Location:
    Pacific Northwest, USA
    Vehicle:
    2007 Prius
    Model:
    Two
    When many of us first get started that's a common thought... However, when you replace a bad module in a pack the module you replace it with if you by it from a quality supplier is going to be thoroughly tested, as well as reconditioned. That means the reconditioned module won't match the rest of the pack. I had to learn this the hard way and the hassle of red triangles coming back a day or two after putting the car back together is something you may want to avoid. :)

    As for a hobby charger, I recommend the "HTRC T240" Duo which is the highest quality for the lowest price. It has both DC and AC inputs, so you can plug your solar system into it and fill your battery pack up with sunshine.
     
  12. PriusCamper

    PriusCamper Senior Member

    Joined:
    Mar 3, 2012
    3,586
    1,305
    0
    Location:
    Pacific Northwest, USA
    Vehicle:
    2007 Prius
    Model:
    Two
    That's the hardest part about working on battery packs... Super precise gear that can accurately track and graph power going into and out of the modules is how you can find good, bad and very best modules. Light bulbs, load tests and hobby chargers come no where near that, which is frustrating!
     
  13. George W

    George W Active Member

    Joined:
    Mar 12, 2018
    547
    292
    1
    Location:
    San Antonio
    Vehicle:
    2008 Prius
    Model:
    Touring
    Thank you for that recommendation. I would prefer to do all the balancing myself, instead of purchasing one that is pre-reconditioned. I don't mind taking the time. If I'm able to recover the weak modules for use in my next Prius that's a bonus.

    If I can pick up a dead Prius for little money, then maybe I'll buy another cylinder pack from 2K1Toaster. A Gen 2 in good condition with new pack for under 3K, still worth it to me. Again, thank you for that recommendation. Going to do a little price comparison before I purchase.
     
Loading...