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Should I be worried about electrolyte loss?

Discussion in 'Gen II Prius Technical Discussion' started by bredekamp, Mar 11, 2009.

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  1. bredekamp

    bredekamp New Member

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    Hi all. Does living in a hot climate reduce the lifespan of the HV battery at all. Someone once mentioned electrolyte loss, but the batteries are sealed are they not? As far I know, batteries enjoy a bit of warmth. It increases their power handling ability.

    Also, I've had my Prius for two years now. In that time I cannot positively recall hearing the battery cooling fan from the vent in the backseat. Will my Prius warn me of a potential battery temp problem?

    By the way, the battery in my car is functioning normally.State of charge is reasonable steady during driving...mostly blue. It does drop kinda quickly with the AC on, but then again it's been 38/39C here!


    Update: These taxis in Australia have batteries that are doing just fine. Oz has the same climate as South Africa....

    http://www.caradvice.com.au/14639/toyota-prius-the-taxi-champion/
  2. magruder

    magruder Average Member

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    I thought the HV battery was dry?
  3. qbee42

    qbee42 My other car is a boat

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    Heat will hurt the life span of NiMH batteries, but not because of electrolyte loss. The HV battery is cooled by cabin air, so use your air conditioning during hot weather to keep the battery cool.

    Tom
  4. bredekamp

    bredekamp New Member

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    Oh yeah. The AC goes on first thing...Was making a video to demo voice command system just now. I decided to switch aircon off and hold my nose and lips by the battery air vent inside. There's a definite flow of air. It's amazing how quiet that radial blower is.
  5. Patrick Wong

    Patrick Wong DIY Enthusiast

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    No point in worrying, since there's really nothing practical that you can do about your traction battery's life. A reasonable number of Classic batteries have failed, in some cases apparently due to electrolyte loss from bad module sealing. It appears that 2G battery modules are more robust and should have a longer life.

    Southern California has relatively moderate climate with summer temperatures into the 90 degree F range. In that season I frequently hear the battery cooling fan running.
  6. bredekamp

    bredekamp New Member

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    Actually, now that you mention it Southern California has the same climate we do. I should have realized....You're right though. No point worrying about something I have very little control over. I'm a slave to AC so the battery should enjoy a cool life too.

    90F is 32C. That is normal but it can go to 102F in February.
  7. bwilson4web

    bwilson4web 03 and 10 Prius

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    You can minimize the heat stress by:

    1. parking in shade - no reason to solar heat the interior.
    2. use "B" when descending large hills (+160 M. hills) - once is not too bad but on a long trip through a lot of hills and mountains, the repeated charging can heat up the traction battery.
    3. Mostly an issue for NHW11 batteries - these first generation batteries have a lighter duty case.
    Feel free to look through my battery work.

    Bob Wilson
  8. David Beale

    David Beale Senior Member

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    A NiMH (and NiCd) are wet cells. They use a basic electrolyte, mostly Potassium Hydroxide and water, but they say it contains a bit of Sodium Hydroxide.
    The Prius cells are "sealed", but have a pressure vent just as all others I have seen do. This is to prevent an explosion in the event of catastrophic failure of the battery charge/discharge control (for example, a short).

    -IF- you managed to get them hot enough (unlikely) they -could- loose electrolyte. The battery management system reduces battery use when it gets too cold or too hot. I haven't noticed the reduction when it gets cold (Pearl still backs out of my garage just fine even when the battery is at -10C and reverses just fine when parked and at -30C - before - the engine starts). I have read reports of the reduction when it gets too hot. The car becomes a bit "sluggish".

    Most electrolyte "loss" is to irreversible chemical reaction, mostly oxidation and subsequent loss of the H2 (the molecule is very small and will diffuse through most seals given enough time). This is a very slow process, resulting in battery life of well over 5 years, barring other failures. This could be considered "the life of the car" in most uses.

    So relax, "DON'T PANIC", and be happy. ;)
  9. mkoskinen

    mkoskinen New Member

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    Have you considered adding a bottle of gatorade to the fuel bladder to replenish the lost electrolytes?
  10. jayman

    jayman Senior Member

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    In practical terms, the NiMH isn't the thing to worry about. The little 12 vdc battery will croak long before you have to worry about the traction battery
  11. EZW1

    EZW1 Active Member

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    And it's a multi-speed fan. I forget if it's 3 speeds or continuously variable, but the battery electronics controls the fan operation.
  12. Flying White Dutchman

    Flying White Dutchman Senior Member

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    thats something new to me

    so you say the prius battery´s wil last 5 years and then start do downgrade...
  13. bwilson4web

    bwilson4web 03 and 10 Prius

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    To the best of my knowledge, no one has published any life-time studies of our Prius traction batteries except for the Arizona Fleet studies. Even in these studies, it was just the NHW11 and Honda Insight. They may have also done first generation Honda Civic hybrids but I'd have to go back and look.

    Bob Wilson
  14. qbee42

    qbee42 My other car is a boat

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    The OP may be worried about electrolyte loss, but how about hair loss? Look what happened to Jayman.

    Tom
  15. jayman

    jayman Senior Member

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    Oh, fun-ee guy ... he he he ...

    Just wait, you'll have a chrome dome soon enough. I can picture it now, you'll wake up one morning, lift your head from the pillow, and those thick locks of hair will REMAIN on the pillow.

    At least, that's about how quickly I lost my hair ....
  16. Flying White Dutchman

    Flying White Dutchman Senior Member

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  17. jayman

    jayman Senior Member

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    No, just receded at a sadly young age. I think qbee42 enjoys teasing me about my chrome dome.
  18. qbee42

    qbee42 My other car is a boat

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    Me? No, I would *never* tease anyone about anything. I am simply too nice to do something like that. :evil:

    Tom
  19. jayman

    jayman Senior Member

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    Don't forget the part about my brute strength ...
  20. qbee42

    qbee42 My other car is a boat

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    I thought loss of hair took care of that?

    Tom
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