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Please Help!!! Prius is loosing it's memory

Discussion in 'Gen II Prius Care, Maintenance and Troubleshooting' started by devinb72, Mar 31, 2012.

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  1. devinb72

    devinb72 New Member

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    I have a 2008 Prius and the for about 2 weeks now it has been spontaneously resetting its memory. I turn the car off as normal, the next time I turn it on it tells me I have no gas, the MPG and Miles have reset, all my radio station presets are cleared. It started after I installed a subwoofer ( but I also installed it a couple weeks after I got it ) I thought the sub was draining the battery, but the car starts fine and shows the battery is one bar from full. So I ruled that out. I have looked on here and Google and I can't seem to find anyone else with this type of problem. Any help would be greatly appreciated.
  2. PaulHS

    PaulHS Member

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    Welcome to PriusChat!:welcome:

    Your Prius has two batteries: the High Voltage battery which is represented on the display, and a 12V battery which boots up the computers, but is not shown anywhere. Your symptoms point to low voltage from the 12V battery, so a full HV battery does not rule out a drain.

    There is a quick and dirty test to check the condition of the 12V battery.

    With the car in IG-ON, raise and lower the driver's window and note the speed. Then turn on your headlights and raise and lower the window, again noting the speed. If the window is significantly slower, a weak 12V battery is indicated.

    Let us know the results.
  3. cwerdna

    cwerdna Senior Member

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    Run the test at http://priuschat.com/forums/newbie-forum/73400-weird-stuff-happening-mpgs-dropping-test-battery.html after the car has sat overnight. You only need to flip between off and parking lights. It's possible your 12 volt is toast.

    On the Prius, the ICE (internal combustion engine) is NOT started by the 12 volt battery. You will never experience "slow cranking" that you would on a conventional car since the Prius has no starter motor and again isn't started by the 12 volt.

    As for "one bar from full", that's referring to the SoC of the big HV battery. More details about the mapping of bars to % at Prius Palm Mileage Simulator.
  4. Mendel Leisk

    Mendel Leisk Senior Member

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    Just wonder why no manufacturers put flash memory in their cars, ie: jump-drive style memory, that doesn't require voltage to be retained. Off topic, I know.

    Maybe impractical? Or cost?
  5. dogfriend

    dogfriend Human - Animal Hybrid

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    Has anyone mentioned that you probably need a new 12V battery? :madgrin:
  6. HaveNoCents

    HaveNoCents Conservative Tree Hugger

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    My wife is losing her memory too. I've checked for a 12v battery but can't seem to find one Anyone know where the battery is on a 1957 Laurie?


    Sent from my iPad using Tapatalk
    1 person likes this.
  7. devinb72

    devinb72 New Member

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    First off, thank you for the reply's. I did the voltage signal check and without it on it set at 11.5v and with it on and charging it went to 14.1 v. So I guess charging it's fine but just sitting their it's a little low. I guess with that I can rule out the sub draining it. I guess I just need a new 12v :)
  8. seilerts

    seilerts Battery Curmudgeon

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    It is possible that the 12V is not being recharged properly while you are driving around having the sub cranked all the way up. The 12V bus is limited to 100 amps, which must power all computers as well as recharge the 12V battery. There is maybe 75 amps to spare in order to run the stereo plus any added amplifiers.

    Put your 12V on a 2 amp charger for several hours today. It is possible that it is just at low state of charge, rather than dead.
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  9. cnschult

    cnschult Active Member

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    I thought woman never forgot anything. Her 12V battery can probably be found with her sense of direction.
  10. qbee42

    qbee42 My other car is a boat

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    What does "loosed" memory look like? Is it like a lightning bolt, or more like a ball bouncing around the interior of the car?

    Tom
  11. Rokeby

    Rokeby Member

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    "... the battery is one bar from full" is a red herring. The "bar" gauge
    represents power in the HV battery. The issue here is the 12V battery.



    +1

    But, I would also question the 12V subwoofer connection.

    I assume that is has it's own power supply. If it were tapped into
    the 12V system at a place where it is always "hot," wouldn't that
    lead to a constant low level parasitic drain on the 12V battery
    even though the car itself was turned off?

    This scenario presumes that the subwoofer is not turned off via
    its own power on/off switch.

    OP, more info on the subwoofer connection is needed.
  12. Nda3rdCar

    Nda3rdCar New Member

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    Looks like a number of people on this thread suggest replacing the 12 volt standard type battery. If you plan to replace the battery yourself...just a suggestion... look into getting a "memory keeper" from PEP Boys or other auto parts retailer. A 9v flat battery in a device that plugs in the cigarette lighter. It provides just enough juice in the system to prevent loosing all those memory settings for the short time it takes to change a battery. About $7. I used one for changing a battery on our Audi (lots of memory settings in that car) and it worked great. Best of luck.
    - Nda3rdCar
    1 person likes this.
  13. Rokeby

    Rokeby Member

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    Nda3rdCar,

    Good idea. However, the fly in the ointment for the Gen IIs at least is
    that neither 12V power outlet is always "hot." :(

    This is to keep from inadvertently running the poor little 12V battery
    down below 11V or so when the car is powered off.

    Here is a $10 solution: Power Outlet Mod
  14. JimboPalmer

    JimboPalmer Nadir of Wrongness

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    I can not stress enough, do not even hint at trading her in on a newer model.
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  15. Nda3rdCar

    Nda3rdCar New Member

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    Damn... I completely forgot about the cigarette lighters going dark. Thanks for the info and link. Coastaletech is a good company. I bolted on their 2" receiver hitch years ago. I will look into that little device.
  16. HaveNoCents

    HaveNoCents Conservative Tree Hugger

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    Already tried. Her trade-in value is not high enough to get one of the 1990 models, and besides the later models seem to have higher maintenance costs. :)


    Sent from my iPad using Tapatalk
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