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Prius motive batteries for other uses?

Discussion in 'Gen 2 Prius Main Forum' started by caffeinekid, Nov 25, 2010.

  1. caffeinekid

    caffeinekid Duct Tape Extraordinaire

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    I am apologizing now if this has already been asked and answered, but is anyone aware of any projects consisting of using used Prius traction batteries for other applications...like backup home power storage, particularly with solar charging?
     
    #1 caffeinekid, Nov 25, 2010
  2. David Beale

    David Beale Senior Member

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    Some have used the Prius as a home power backup, but the battery has such low capacity that using it alone wouldn't help much. It's a 6.5 A-Hr 200V battery.
     
    #2 David Beale, Nov 26, 2010
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  3. caffeinekid

    caffeinekid Duct Tape Extraordinaire

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    Well, depending on usage time, that would be plenty for running a light circuit with several 14W 0.2A VFLs. Add another module and you could have fans and relatively efficient small appliances used intermittently.

    I haven't really compared them price-wise based on specific energy with what is typically available for backup storage, but I suspect that they can be picked up (used) for a lot less. I am thinking in terms of both individual cells and complete modules.

    I am hoping to get some pointers from anyone in the know. Maybe there is a flaw in my thinking on this?
     
    #3 caffeinekid, Nov 26, 2010
  4. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Suppose that you can buy a used 2G traction battery for $500. Also suppose that you can get 5 Ah out of the battery at 220VDC. This amounts to 1.1 kWh. Now you have to figure out how to convert 220VDC to 120VAC. You also have to figure out how to recharge the battery without blowing it up.

    Compare to buying 4 12V deep discharge batteries from Costco for $80-90 each. Suppose those batteries are rated at 50 Ah each. 600 Wh per battery x 4 = 2.4 kWh or more than 2x the capacity.

    With this back of the envelope analysis, it looks to me that you would be better off buying some 12V deep discharge lead acid batteries, connecting them in parallel, and attaching to a 12VDC to 110VAC inverter and a 110VAC to 12VDC charger, both of which are plentiful and relatively inexpensive.
     
    #4 Patrick Wong, Nov 26, 2010
  5. David Beale

    David Beale Senior Member

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    Add to what Patrick posted, if you attempt to use them after taking them apart, be very careful. The voltage is the least of your worries. If you attempt to charge them when they are apart they expand like an accordion! There's a picture of this somewhere on this forum.

    The 12V battery route is a much less expensive and easier to do way to go. There are almost unlimited options re equipment you can use, such as inverters, motors, fans, whatever at 12V. You can even get Optima deep discharge batteries (65 A-Hr) that can be used indoors and that don't leak or emit vapours.
     
    #5 David Beale, Nov 26, 2010
  6. bwilson4web

    bwilson4web BMW i3 and Model 3

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    #6 bwilson4web, Nov 27, 2010
  7. kenmce

    kenmce High Voltage Member

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    here you go, $ 10/module.
     
    #7 kenmce, Nov 27, 2010
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  8. caffeinekid

    caffeinekid Duct Tape Extraordinaire

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    Thanks a lot for the responses. I have negotiated a barter deal where I could take three GenII modules in exchange for $1800.00 worth of equipment that at my cost is ~ $200.00. There is a slight gamble as to whether or not the modules have been depleted, but it is worth it IMO considering the paperwork on the VINs does not show any lengthy storage time. I would just like to have a use for the modules if I do this and would not be interested in the deal if I had to resell them. Seems like the perfect opportunity to do a little experimenting. :)
     
    #8 caffeinekid, Nov 27, 2010
  9. David Beale

    David Beale Senior Member

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    Even if the modules are "fully depleted" they are NiMH cells and can be recharged. If they have failed due to internal shorts or electrolyte depletion then they are paperweights (though electrolyte depletion may be fixable by adding Potassium Hydroxide solution - concentration you will have to look up yourself). Do note you should put them in a mechanically restricted housing -before- attempting to use them. See the original packaging Toyota uses for hints.
     
    #9 David Beale, Nov 28, 2010
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