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Long term trickle charging

Discussion in 'Gen 2 Prius Technical Discussion' started by Syclone, Dec 11, 2011.

  1. Syclone

    Syclone Member

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    We are going to be away from home for several months and my 2006 Prius will be in the garage for that time. In the past, we either took the car south, or had a friend use it while we were away. For this trip I have been considering using my Shumacher SEM1562A (Maintain 1.5 amp) charger to keep the 12 volt battery charged. I've used this in the past for another car (a 1999 BMW 528I) and have recently come to suspect that doing this for 4 years has, essentially, 'cooked' the battery. In recent weeks the battery has exhibited very little capacity, completely dead in the morning after one start (no restart power after stalling in the first few seconds). That battery was installed in 2008 and being in the trunk area in a garaged car gets almost no stress.

    So the question is: Do I take a chance with the trickle charger or do I just shut off the proximity key switch and hope for the best?

    How long will the 12 volt battery keep its charge with just minimal drain?

    And lastly, What would be the down side of just disconnecting the 12 volt battery, other than having to reset the station memory on the radio?
     
  2. Hal W

    Hal W New Member

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    I use a 2 amp trickle charger[floater type] on my 06 often. My 12v is the original and still holds the charge.I am not sure how much longer it will last[12v that is!] I hear so many horror stores about the Prius and the 12V! Hal
     
  3. David Beale

    David Beale Senior Member

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    If you have a voltmeter you can check the charger. It should eventually settle at 13.2-13.6 V for long term "maintenance". Any higher and you will loose too much water. Much lower and the battery could sulfate.

    The other battery failed after four years? I would suspect that was because it had reached normal "end of life".

    If you disconnect the Prius 12V battery you will have to reset the radio presets and the auto window down/up on the drivers side. If it's going to sit without use it would be ok to disconnect it, but I wouldn't do that for more than about three months without charging it.
    Note that you may have to press the "ON" button twice due to the car's computers getting "confused" when you reconnect it. Not a big deal, just a warning so you don't panic.

    Charge up the battery first overnight, then disconnect the negative terminal and put a plastic bag over it to ensure it doesn't accidentally reconnect.
     
  4. M8s

    M8s Retired and Lovin' It

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    We leave a 2009 (bought in 9/08) in our unheated Colorado garage for 6 months each winter. We attach an Optimate 3+ battery charger (a "smart charger" that runs periodic battery tests and charges the battery only when necessary) and have not had any issues to date.

    We also have a neighbor who disconnects the charger and starts the car every 6 - 8 weeks and lets it run until the ICE turns off (takes 8 - 10 minutes). But that is to keep the traction battery charged.
     
  5. edthefox5

    edthefox5 Senior Member

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    I looked at your charger and its a floater so it should be good to go.
    But how hot does that charger itself get? I have a cheapo smart float to and it floats great but man it gets really hot. I would not use it in my absence because I would be afraid of fire. Houses usually burn down from electrical fires.

    If yours does not get hot use it. If it gets really hot I would not. I would disconnect the negative terminal of the battery at the trunk. Charge it up real good and it should be fine in the trunk for 2 months disconnected. No worries while away.
     
  6. R-P

    R-P Active Member

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    Float charge: Flooded = 13.2-13.7; Gell cell 13.2; AGM 13.2 -13.4

    We seem to have an AGM.

    Found the info today when searching if I could add water to our AGM battery. It also has some info on the need for temperature adjusted charging voltage...

    Here's the interesting read.
     
  7. KK6PD

    KK6PD _ . _ . / _ _ . _

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  8. M8s

    M8s Retired and Lovin' It

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    Ed, I don't know whether you were referring to the Optimate 3+ in my post but it doesn't get hot. Just a little warm. Same with the Optimate 4 I use for the Miata we leave in AZ over the summer. As a precaution I do leave them sitting on a concrete floor a few feet away from combustible materials, though.
     
  9. edthefox5

    edthefox5 Senior Member

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    No I was referring to the OP. But if just warm that's perfect on the concrete floor.
    My cheapo eBay $15. float gets so hot you can't touch it. Gonna have to get a good one.
     
  10. vertex

    vertex Active Member

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    If you charge up the traction pack so the bars are green, and you disconnect the negative battery terminal, you should be fine for 6 months. I had my traction pack out for 8 months, and it worked fine. I have another car that I diconnect the 12 volt battery on for 8 months, and never have an issue.