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Q: Why does decreasing load matter during discharge?

Discussion in 'Gen 2 Prius Technical Discussion' started by jeff652, Oct 25, 2014.

  1. jeff652

    jeff652 Senior Member

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    II
    A: We are often asked why lower wattage bulbs should be used with our Simple Discharger as the battery pack is drained. The lower wattage bulb allows the battery to do more "work", taking a much longer time period to drain the battery. Because the pack can support the lower load for this longer period of time, more energy is able to be extracted from the battery pack.

    Here is a comparison of an Insight IMA battery that is already "empty", i.e. drained to the bottom of its normal operating range. It is only able to support the load of a 200W bulbs for a couple minutes, but is able to carry the 15W bulbs load for almost an hour.

    200w 15w discharge comparison.PNG

    I'm planning to add a current logger as well to compare the amount of Ah extracted from the pack in each scenario as well. Stay tuned :)
     
    #1 jeff652, Oct 25, 2014
  2. Britprius

    Britprius Senior Member

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    The pack when being discharged at the higher rate has more internal losses "heat" than at the lower rate. This is due to the current flow through the batteries internal resistance. Another thing that affects all batteries to some degree is the "Peukert effect" of different discharge rates.

    John (Britprius)
     
    #2 Britprius, Oct 26, 2014
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