Two Traction Batteries in Parallel?

Discussion in 'Gen 3 Prius Accessories and Modifications' started by Bill the Engineer, Jun 30, 2014.

  1. Bill the Engineer

    Bill the Engineer Senior Member

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    Disregarding the space it would take (since I am working toward Frankenstein"s hybrid anyway,) what challenges would I face in connecting two traction battery packs in parallel to get the added EV power? I know I would need twice the cooling equipment, but electrically are there any pitfalls?

    Bill the Engineer
     
  2. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    You are going to need twice the number of inverters, and possibly, twice the number of radiators. (and a lot of new software)

    When you put electrical items in parallel, they have one half the resistance and twice the power. Your inverter is not going to know what to do with either.

    I know this is a crazy idea, but if someone made a Prius PHV available for retails sale, perhaps you should trade your currently undamaged Prius in for one. (Since Toyota does not know how to get that much power from it's inverter, they cheat and use external plug in electrical sources)

    There are (were) a ton of aftermarket ploys to add batteries, to my knowledge they all needed a plug in charger.
     
  3. jdenenberg

    jdenenberg EE Professor

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    One way would be to repackage the two HV batteries so that each monitored pair of modules would now consist of two module pairs in parallel so that the battery ECU could track the SOC of all of the modules (now as 14 quadruples). The rest of the system would then operate normally.

    JeffD
     
  4. GrumpyCabbie

    GrumpyCabbie Senior Member

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  5. Easy Rider

    Easy Rider Active Member

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    Doesn't ANYBODY ever read other active threads before they post a redundant question ??

    The simple answer is: Unless you have, or create, a plug-in hybrid in the process, simply putting in more battery capacity will NOT gain you anything useful. Since ALL of the energy used comes from the gas engine anyway.......and there are losses involved with charging and discharging the battery, you might actually end up worse off.

    And as mentioned already, the extra equipment and programming changes would make the change cost prohibitive anyway.

    Do you NOT think that the Toyota engineers did extensive testing before deciding on the proper capacity for the battery ??
     
  6. mrbigh

    mrbigh Prius Absolutum Dominium

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    I think someone tried this a number of years ago and the pack blew up;

    Aminorjourney.com | Life is one little trip… | Page 5


    That was an unsupervised daily recharge and with a lack of charging monitoring equipment.
    I ran up to 4 OEM packs in parallel for several years, with the right gear and electronic interfaces.
    Today days, this type of equipment is not longer available from the manufacturer due to lack of sales and crowd interest
     
  7. GrumpyCabbie

    GrumpyCabbie Senior Member

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    It was, but it answered the ops question. What challenges and pitfalls would he face.
     
  8. bisco

    bisco cookie crumbler

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    but it was just a short.:eek:
     
  9. Bill the Engineer

    Bill the Engineer Senior Member

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    I got the information that I wanted, a summary of the pros and cons. As usual, I had a good reason for asking. One of the uses of my "Convertible Hybrid Project" vehicle when it isn't good weather outside will be as a power back-up for the house I plan to build near the beach when I retire. I plan to install a power-out module from Converdant to power essential items like the refrigerator and freezer in the house during severe weather power outages. The question was based on the premise that the extra storage capacity of two traction batteries would cause the IC engine of the car to cycle on less often during these times. However, I see from the above that it is probably wiser to stick with the one traction battery and let it cycle as needed. The power tap can also power a small exhaust system attached to the tailpipe during these times. The garage that I plan to build will have an additional internal roll door to isolate the car two garage rooms away from the living space in the house at these times to prevent exhaust fumes from entering the living area.
    [​IMG]

    I have lived in a mid-Atlantic shore town before in my college days. There is no question that occasionally the power WILL go down, and usually at the most inconvenient times.

    Bill the Engineer
     
  10. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    I have read write ups on PriusChat about using your big battery to fool a UPS into having a never ending battery, that the Prius keeps charged. Such a rig could have the battery it came with, that it charged; and the Prius Battery charged by the car. I do not think you could have both batteries online at once as they would not be balanced. But the UPS battery could be instant on, and the Prius battery be 'never ending'.
    Introduction to the PriUPS Concept
     
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