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Aux battery discharged

Discussion in 'Gen 2 Prius Technical Discussion' started by Kurtp2, Aug 25, 2015.

  1. Kurtp2

    Kurtp2 Junior Member

    Joined:
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    Vehicle:
    2005 Prius
    Model:
    Three
    My auxiliary Optima battery somehow mysteriously discharged to 5.6 volts after working fine the day before, and after a rainstorm. It is now trickle charging. I need to travel in 2 days and don't want to be stranded. Any idea on what caused this? Can I use an off-shelf replacement as back-up?
     
    #1 Kurtp2, Aug 25, 2015
  2. bisco

    bisco cookie crumbler

    Joined:
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    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
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    Plug-in Base
    hopefully, you left a door/light on. yes you can, but the optima should be ready for your trip. that's one of it's strong points, the ability to deep discharge without much degradation.
     
    #2 bisco, Aug 25, 2015
  3. CooCooCaChoo

    CooCooCaChoo Senior Member

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    LE
    Yeah, the Optima Yellow top is an AGM battery that is more tolerant of deep cycle charging, but I would be weary of what caused it to discharge in the first place.
     
    #3 CooCooCaChoo, Aug 26, 2015
    bisco likes this.
  4. RobH

    RobH Senior Member

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    Sunnyvale, California
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    2006 Prius
    I had a dead battery after leaving an interior light on for two weeks. The fun part was that I recharged it with one of these modern chargers that automatically switches between 6 and 12 volts. When it got the dead battery up to something like 7 volts, it said "done". I guess a fully charged 6 volt battery reads about 7 volts. In order to get past 7 volts, I had to connect it to a 12 volt battery for a while. That was enough to switch back to the 6/12 volt charger and let it go the rest of the way up to 12+ volts. What ever happened to switches?
     
    #4 RobH, Aug 27, 2015
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