Aux Battery Date Help

Discussion in 'Gen 2 Prius Technical Discussion' started by labumm, Oct 2, 2012.

  1. labumm

    labumm Junior Member

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    I just replaced the aux battery in my 2004 Prius @108.5 k. I am pretty sure this is the original aux battery.

    Below is a collage of photos.

    How do I tell the date of the battery?

    Aux_battery_original.png
     
  2. bisco

    bisco cookie crumbler

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    august of 03?:confused:
     
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  3. Patrick Wong

    Patrick Wong DIY Enthusiast

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    210803 = August 21, 2003
     
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  4. labumm

    labumm Junior Member

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    Makes sense. Thanks!
     
  5. uart

    uart Senior Member

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    Woohoo, a bit over 9 years on the OEM battery. That's a pretty good run by any standards. :)
     
  6. labumm

    labumm Junior Member

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    The battery's demise was pretty sudden. I accidently shorted the dome light replacing the festoon lamp, blowing the 15A dome light fuse--as I discovered later. I was doing this at dusk, and everything went dark.

    I thought the lights timed out. So I tried to start the car. The dashboard started to light, then immediately faded out. Only a soft green glow fron the start button when I inserted the smart key into the key socket. No life. Battery at 12.6V. Break lights working fine. I would have expected more life.

    I put the battery on a charger. It's voltage undercharge came up to 15V in a few hours. The car would still not start, although I did hear Prius noises from the engine compartment. The voltage came down to 13.8 when trying to start it. I tried unplugging the two connectors from the + side for 10 min, but that did not help.

    The observed behavior of the battery makes sense to me for a weak battery. However I am confused by the behavior of the Prius in this instance.

    SPH-D700 ? 2
     
  7. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Are you confused because the Prius refused to start with a blown 15A DOME fuse?

    If yes, then please recognize that the DOME fuse provides power to much more than just the overhead cabin light. It also provides 12V power to certain ECUs and that is why, with a blown fuse, the Prius will not become READY.
     
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  8. labumm

    labumm Junior Member

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    Ok. Got me on that one. With all the circuits, I would not have suspected the dome fuse circuit would be critical to the Prius function.

    So the battery was actually still servicable. The fuse was the problem. I did not check the fuses and find the blown dome fuse until the next day when installing the new battery. And there is a spare 15A in the fuse box with the fuse changing tool too.


    SPH-D700 ? 2
     
  9. labumm

    labumm Junior Member

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    Here is what relies on the 15A Dome circuit from p 372-373 of the section J of the wiring diagram.

    Air Conditioner
    Automatic Glare–Resistant EC Mirror
    Automatic Light Control
    Back–Up Light
    Brake Control System
    Clock
    Combination Meter
    Cruise Control
    Door Lock Control
    Engine Control
    EPS
    Garage Door Opener
    Headlight
    Headlight Beam Level Control
    Interior Light
    Key Reminder
    Light Auto Turn Off System
    Luggage Compartment Door Opener
    Multi–Display and Audio System (Built–in Amplifier)
    Multi–Display and Audio System (Separate Amplifier)
    Power Window
    Push Button Start System and Hybrid Vehicle Immobilizer System
    Rear Window Defogger and Mirror Heater
    Seat Belt Warning
    Shift Control System
    Smart Entry System and Wireless Door Lock Control
    (w/ Smart Entry System)
    SRS
    Taillight and Illumination
    Theft Deterrent
    TOYOTA Hybrid System
    Wireless Door Lock Control (w/o Smart Entry System)
     
  10. 2006_HK

    2006_HK First Hybrid

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    I am now wondering if your 9 year old battery is still in tip-top shape. The voltages you mentioned seem to be too high for a 12V battery.

    I would expect your battery to measure below 12V when cold loaded (pressing start button twice without the brake). Now that your old battery is out of the vehicle, could you measure and let us know the voltage once it has been sitting for a while?
     
  11. labumm

    labumm Junior Member

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    The battery was still servicable. 12.6V. The whole problem here was the dome circuit fuse. Just never occured to me that the Prius could be disabled this way. Easier than removing the distributor cap...

    On the up side. I have owned the car for 9 years and do not plan to replace it yet. So I would likely need to replace the aux battery at some point. Replacing it now gets me a new battery that should last for the life of the car.

    The story of the replacement aux battery is this. The battery store has a agreement to only sell the replacement battery to Toyota. I got lucky in that they had a new battery that had been sitting on the shelf for too long. So they could no longer sell it as new. As a result, they could sell me the "used" battery for $35. SOLD
     
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