1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Voltage float.

Discussion in 'Gen 2 Prius Main Forum' started by Prius92, Aug 12, 2022.

  1. Prius92

    Prius92 Member

    Joined:
    Sep 14, 2019
    376
    95
    0
    Location:
    Iowa
    Vehicle:
    2008 Prius
    Model:
    II
    Ok, if you apply a load to any module, once the load is removed, the voltage will float back up.
    Usually a discharge to 6V will float back up to around 7.2-7.4V after a few hours.

    I am reading to balance modules before installation, as modules have to be within a certain voltage range of each other to prevent error codes, to use a light bulb to put each module at 7.2 or 7.4V.

    But...if one was to remove the load, I imagine the voltage will float back up, but I doubt this float up would be the same voltage for each module?
     
    #1 Prius92, Aug 12, 2022
  2. tracy ing

    tracy ing Active Member

    Joined:
    Dec 22, 2017
    384
    167
    0
    Location:
    wash dc
    Vehicle:
    2005 Prius
    Model:
    N/A
    Voltage alone cant be used to manage lithium nicad nimh, or else industry would use voltage.

    You CAN use voltage where it DEVIATES the most, thats when the cell is NEAR EMPTY or NEAR FULL.

    Thats why I recommend you discharge to some lower voltage, like 7 volts, or 6 if you can, then insert a MEASURABLE AMP HOUR into each module. By that i do not mean 1 amp hour, thats up to you, You can probably just insert 1/2 amp hour and that would be enough to have the car operate and charge the pack itself.

    You are interested in the pack being installed with all the modules having NEAR the same capacity, not voltage. If you had a grid charger, took them all to 6 volts, then grid charged them up, that would be ideal. Lacking that, discharge them, and charge each module at the same RATE and for the same TIME. They still wont be perfect due to self discharge.

    If you spend a month testing and rating for that (self discharge), then do the math, you can insert a different amount in each one to achieve near perfect balance (because you lack a grid charger) but, even I would not attempt to do it that way lol.

    NOTE I HIGHLY recommend you final balance using the LOW end and do not simply charge the modules to 100% and insert them in the pack, If you charge to 100%, the pack will go out of balance sooner, this is based on my PROVEN EXPERIENCE doing this.
     
    #2 tracy ing, Aug 13, 2022
(You must log in or sign up to post here.)