Best new (2016) charger/ballancer for reconditioning the hybrid battery

Discussion in 'Gen 2 Prius Technical Discussion' started by romanlutsk, Dec 12, 2016.

  1. romanlutsk

    romanlutsk Junior Member

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    Originally I posted this as a comment in an old thread (Best Charger/Conditioner for Balancing Traction Battery | PriusChat), but nobody seems to have noticed, so here we go:

    I ended up with a bunch of 2001 and 2004 battery modules and would like to test/recondition them to see which can still be used.

    Any suggestions on some good chargers for this purpose (the modules are loose outside of battery pack, so I'll have to do them one by one)? I've seen some suggestions from 2012-2013, but nothing more modern/recent, taking into account new chargers that became available in late 2016.

    My understanding is that the charger has to be capable to doing at least 6.4A with NiMH peak charge feature and cycle through deep discharge/charge 3-5 times.

    So far I've found these (in the order my preference):

    Ultra Power UP120AC Duo Dual Port Charger ($80, two 12A ports, built-in AC power supply)

    Eachine Touch T100, 7A, 100W (touch screen, AC in, $65)

    HiTec 44167 X4 AC Plus 4-Port AC/DC Multi-Charger (4 ports, $200)

    IMAX X350 More Power 350W 15A Intelligent Touch Screen Charger ($80, single channel).

    Thoughts, comments ? (which one is the best? Any other chargers worth considering (my budget is around $70-100)). Thanks!
     
  2. John Valkenburg

    John Valkenburg Junior Member

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    There are two issues that I consider after purchasing multiple chargers:the discharge time and the feedback data from the charger.
    The cell packs are 7.2 V at 6.5 amps = 46.8 watts. the toal charge time is governed by the charge power and discharge circuit power rating.
    Many chargers will charge at 50 watts,but only discharge at 5 watts.
    many chargers do not record the result of all the charge/discharge cycles, but only display the final discharge current.

    Some chargers have a 5 watt discharge rating, which takes 10 hours to discharge. A charge cycle of .33C or 2 amps requires 6.5 / (1.2 x 2) = 2.7 hours to charge (Panasonic battery info indicates 20% loss of current during charging cycle: hence x 1.2). Discharge time for a 5 watt discharge circuit is 5/7.2 = .7 amps; 6.5 / .7 = 9.2hours (for a new cell). The total cycle time for the 5 watt discharge and 2 amp charge is 2.7 + 9.2 = 12 hours.
    The actual time will be closer to ten hours since the cell pack capacities will be anywhere from 3.5 to 6 amp-hours.

    A good cell pack will probably require 3 cycles, while a stubborn cell pack may require 15 cycles. It makes sense to charge and discharge at at least the same rate, although the discharging could be closer to 2.5 amps since during discharging, the voltage is also lower and the power dissipation in the cell pack would be lower at the same current. Therefore, for 2.5 amps, the discharge circuit power should be 7.2 x 2.5 = 18 watts. The total cycle time for the 2-amp charge/2.5 amp discharge - charger would be 2.7 + 6.5 /2.5 = 5.3 hours per cycle.

    If 20 cell-packs require 3 cycles, 8 cell packs require 15 cycles, the total charger time is 20 x 3 + 8 x 15 = 180 hours.
    Since charger switching is manual as most of us have a daytime job, add an additional 80 hours wasted since these will terminate during the night etc.
    This is why re-balancing can end up taking a month. A dual charger with 10 watts per channel discharge is not much slower than a quad charger with a 5 watt per channel discharge current.
    My suggestion is to consider the feedback provided and the discharge rates when considering which charger to purchase.
     
    kdfchannel and SFO like this.
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