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Flat auxilliary battery after 800 miles

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by maxvok, May 31, 2004.

  1. maxvok

    maxvok New Member

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    Since getting my car 2 months ago, I have been driving mostly 20-40 miles stretches twice a week in daytime and once 200 miles on one day. Last Friday, after 3 days in my garage, I could not open the locked doors and to use the manual key. Indoor light was very dim and starting was impossible.

    Talking to my dealer's mechanic he could not explain the reason and suggested to call Toyota's emergency service in the Netherlands. Mechanic mentioned that while my car was 2 weeks in their showroom prior to delivery, they had connected the battery to a charger to avoid that it would be drained while being inspected by the many customers. Anyhow even if it had not been fully charged, I would expect it to be OK after 800 miles driving. He also said that the capacity of this battery was very limited (does anybody know how many kW, cannot find it in the specs) and that leaving the lights on for 10 minutes could cause it. But this did not apply to my case as I did not notice anything abnormal 3 days earlier while driving without lights and all power is automatically shut off, including courtesy light, when I lock the doors.
     
    #1 maxvok, May 31, 2004
  2. DaveinOlyWA

    DaveinOlyWA 3rd Time was Solariffic!!

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    21 kilowatts
     
    #2 DaveinOlyWA, May 31, 2004
  3. richard schumacher

    richard schumacher shortbus driver

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    "21 kW" is a power, not total energy stored by the battery. The 12V battery certainly cannot supply 21 kW for any length of time without damaging itself; that would imply a current of about 1600 Amps.

    The original poster's problem sounds as if there is a problem in the charger for the 12V battery, or possibly some accessory was left on and failed to turn itself off.
     
    #3 richard schumacher, Jun 1, 2004
  4. DaveinOlyWA

    DaveinOlyWA 3rd Time was Solariffic!!

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    richard:

    the battery is 201.6 volts so that would be just over 104 amps at 21kW.

    But you are right, I did give charge. the capacity is 6.6 amp-hours at 35 degrees C.

    obtw, the maximum charge is 50kW from the ICE at 500 volts which is the same amperage..
     
    #4 DaveinOlyWA, Jun 1, 2004
  5. richard schumacher

    richard schumacher shortbus driver

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    The described problem implicates the 12V battery (which powers the dome lights et cetera) or it's charging system, and not the 201.6 V traction battery.
     
    #5 richard schumacher, Jun 1, 2004
  6. DaveinOlyWA

    DaveinOlyWA 3rd Time was Solariffic!!

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    ok i c...

    it doesnt really matter anyway. his problem isnt the battery capacity, its something else. bad battery, short...
     
    #6 DaveinOlyWA, Jun 1, 2004
  7. maxvok

    maxvok New Member

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    the best explanation I got sofar from another Yahoo forum is that the battery had been probably completely depleted in the showroom and that the recharging was not done properly if it was not already lost anyhow. Dealer concurred immediately and wil get replacement under guarantee.
     
    #7 maxvok, Jun 1, 2004
  8. DaveinOlyWA

    DaveinOlyWA 3rd Time was Solariffic!!

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    i find that hard to believe. you have driven the car more
    than enough to have charged a dead battery. you have
    other issues i believe. I would have the dealer check the
    car out.
     
    #8 DaveinOlyWA, Jun 1, 2004
  9. 8AA

    8AA Active Member

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    Another thing to keep in mind is that the Prius does not have an alternator to charge the 12v auxiliary battery. My understanding is that it gets it's charge from the inverter connected to the traction battery, but that only occurs when the vehicle is on. I would be interested to hear how long a Prius has to be "on" to recharge a discharged (but not fully depleted) auxiliary battery.

    It does sound like the problem was either a defective battery, or a problem with the recharging circuit. Hopefully it was just the battery. Let us know what the outcome is.
     
    #9 8AA, Jun 2, 2004
  10. maxvok

    maxvok New Member

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    Here are two comments I got:

    # 1

    Unless the dealer used a battery charger that had a "float" function in it, they may have fried the the auxiliary battery by leaving the charger connected continuously.

    # 2
    Once a lead-acid (or any other lead-chemisty battery) has been deep-discharged below ~1,7 V per cell (~10,2 V with a standard car battery) and remained below that level for a couple of hours, it's basically dead.
    Charging it might help a little, but you'll probably never get more than
    10-20% of the rated capacity from it. With an ordinary car, that would be
    way too less energy to crank the ICE, so you'd notice immediately.

    With the Prius, even such a very weak battery is capable of reliably
    starting the car for months (I actually knew that my battery was dead for
    about 3 months now, but was too lazy to replace it on my Prius I) if you
    don't let the car sit in between too long...

    I believe the lead battery is rated at 34 Ah / 12 V, so the capacity is 0,4 kWh.

    Have your dealer replace the battery under warranty.

    BTW: The NiMH can sit for at least 1 year before by self-discharge it's charge drops too low. But unlike Lead-Acids, NiMHs don't deteriorate that fast once they are stored w/o charge or with partial charge.


    Understood from mechanic that there is a special "Prius charger", will try to find out more about this and report.
     
    #10 maxvok, Jun 2, 2004
  11. richard schumacher

    richard schumacher shortbus driver

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    The "special Prius charger" is for the 201.6V traction battery, not for the 12V accessory battery. There's nothing special about the 12V battery except for the terminals.
     
    #11 richard schumacher, Jun 2, 2004
  12. casc

    casc New Member

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    Any aftermarket gear installed?

    Another possibility for flatting a battery is if there's an extra drain on it.
    So if for instance you have an aftermarket stereo that draws power to
    maintain memory settings or a ham radio that decides to misbehave :oops:
    you can drain the 12 volt system, especially if the battery was already compromised to begin with.

    Haven't flatted the 12 on my Prius yet.... but just had to charge the truck battery because I let it sit too long while I drove the Prius <grin>

    cas (driftwood #7)
     
    #12 casc, Jun 3, 2004
  13. Steve Goldenberg

    Steve Goldenberg New Member

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    I had that problem once. I must have left something on. I used a small jump battery with cables using the easy terminals under the hood. It started right up and never reoccurred. For the future, I bought a very small Auto Start Battery. It charges irself from the cigarette lighter. I fixed the dash power outlet to be on all the time (CoastalTech mod) so if it happens again, I'll just plug it into the always on cigarette lighter outlet and it should power up the computers instantly.
     
    #13 Steve Goldenberg, Jun 5, 2004
  14. maxvok

    maxvok New Member

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    It was mentioned by two mechanics from different dealers and when my defective (?) battery was replaced, the mechanic showed me the 12V 10AMP BURNSON 3 step charger Type 2047 Out 14.7 V DC Standby 13.7 V DC which they had received from the importer for the Prius. We could not detect anything special about it, so it remains a mystery. :p
    They were not aware of the existence of a charger for the traction battery
     
    #14 maxvok, Jun 7, 2004
  15. richard schumacher

    richard schumacher shortbus driver

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    Hmm, they should ask Toyota about it. Eventually they're going to get a customer who installed the EV-only button and forgot to turn it off, or who wanted to see how far he could go without gas, or did some other damned fool thing :_> to drain his traction battery, and then they will need the special high-voltage charger.
     
    #15 richard schumacher, Jun 7, 2004
  16. siai

    siai Junior Member

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    The auxiliary batteries on the Prius do drain over time. It is better in the '04 then the Classic. The battery is small and various memory circuits put a load on it. On the '04, if you have the keyless entry (which you must according to your post) you should turn it off with the switch under the steering column if leaving it for an extended period of time. I added the XM tuner to my '04 and the memory circuit in it also adds to the drain. When I leave the car for an extended time, I put a small trickle charger on it to maintain the auxiliary battery. I any event, if the battery is discharging in a few days that's abnormal. I agree with earlier posters that you should have the dealer either resolve the problem or at a minimum make a note of it if the battery fails in the future. Starting batteries don't like deep discharge cycles and I can tell you from experience on the Classic, that little battery isn't cheap :x
     
    #16 siai, Jun 10, 2004
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