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What would happen if.....

Discussion in 'Gen 2 Prius Technical Discussion' started by FirstFlight, Jun 17, 2012.

  1. FirstFlight

    FirstFlight Member

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    ...I were to throw another 28 module OEM battery (Gen 2) in the trunk area and connect the two batteries in parallel? It's more of a hypothetical question and something I don't understand with a system like Enginer.

    If the battery is connected correctly, the computer (I assume the battery ECU) can keep track of the charging and discharging, and from what I understand the Enginer system doesn't work like that. It's an assist and when the add-on battery is dead, it's dead - the Prius won't charge it. The only problem I can imagine with two OEM batteries in parallel is that the computer is expecting to charge 182 Ah when in fact there is the capability of charging 364 Ah. Would it charge both batteries but only to 1/2 of the level it normally would?
     
    #1 FirstFlight, Jun 17, 2012
  2. Britprius

    Britprius Senior Member

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    The ah capacity of the hv battery in total is only 6.5ah of that only about 40% is used by the Prius.
     
    #2 Britprius, Jun 17, 2012
  3. FirstFlight

    FirstFlight Member

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    Each module is 6.5Ah so you're saying that since they are connected in series that it's still 6.5Ah, except it's not 6.5Ah at 7.2V, it's 6.5Ah at ~200V? I guess Ohm's law would apply here.

    But my other question wasn't answered. Would the Prius charge both to 50% of what it typically does?
     
    #3 FirstFlight, Jun 17, 2012
  4. Britprius

    Britprius Senior Member

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    The Prius basically does not charge the battery by checking the voltage, it counts coulombs in and out to stay within it's design capacity range so although putting two batteries in parallel will lower the internal resistance by half in theory making more current available (better acceleration) The batteries would not be charged to capacity and you would be carrying extra weight.

    When battery cells are in series the amp/hr capacity of the battery as a whole is that of the lowest capacity cell (or module), when they are in parallel the amp/hr capacity is the sum of the amp/hr capacity of all the cells.
     
    #4 Britprius, Jun 17, 2012
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