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12V Battery Dead - Could Solar Roof Ventilation Be The Cause??

Discussion in 'Gen 3 Prius Technical Discussion' started by krouebi, Jun 24, 2010.

  1. krouebi

    krouebi 2012 Peugeot 3008 HYbrid4

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    Hi there,

    After 21,600 blissful and completely trouble-free kilometers our Gen3 Prius acted up seriously the other day - with a completely dead 12V battery :eek:. Not funny - especially as we're on vacation in the Basque Country in SW France!
    Although the problem was quickly solved with a booster, we wonder what could have caused it. The car had been left standing for 3-4 days, but it has survived much longer standstill periods without any problems. This is, however, the first time it's been sitting in a daytime-sunny parking lot with the solar-powered ventilation working - and, indeed, when I finally got the car opened with the emergency key the fan was happily working away :cool: .
    The day before we experienced the dead battery I unlocked/relocked the car to get something in it - but as it will refuse to lock if a door is open, no interior light could have been left on.
    The only "logical" culprit seems to be the solar ventilation - could it be that it - although mainly solar powered - still draws a minor amount of current (just enough to drain the battery completely)?
    A compact battery booster is definitely on the "to buy" list - although assistance was relatively quick to come, one of those things (readily accessible inside the cabin, of course) would have been very handy.
    Anyone have a guess what could be the reason - and would an incident like this have left any interpretable error codes (I have a ScanGauge - and otherwise the next Toyota dealership can have a go with their tester) ?
     
    #1 krouebi, Jun 24, 2010
  2. V8Cobrakid

    V8Cobrakid Green Handyman

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    isn't solar ventalation isolated with it's own 12v? i heard it makes too much electrical noise with the computers and audio.
     
    #2 V8Cobrakid, Jun 24, 2010
  3. JimN

    JimN Let the games begin!

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    Since you already have a ScanGauge use it to keep an eye on your voltage readings. Is the battery fully charged? Does it hold a charge? Battery failure won't trigger a DTC.
     
    #3 JimN, Jun 24, 2010
  4. qbee42

    qbee42 My other car is a boat

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    No possible connection. The solar power is on its own bus.

    Tom
     
    #4 qbee42, Jun 24, 2010
  5. David Beale

    David Beale Senior Member

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    You either:
    1. Switched on a/some interior lights (the switches are three position for the overhead lights, off, door, on).
    2. Left the headlamp switch in the on position (not sure if your country version will do this but check) and exited from the passenger door (did not open the drivers door).
    3. Sat in the car listening to the radio etc. with the lights on and car off (in accy for example).

    The headlamps will drain the battery in less than 5 hours if the car is not in ready.

    Note that different country models operate differently. For example, the Canadian car is actually different than the US car in the headlamp switch operation. So you will have to determine how your car works, but the above should give you a clue as to what happened.
     
    #5 David Beale, Jun 24, 2010
  6. macman408

    macman408 Electron Guidance Counselor

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    I'll add #4 to David's post: perhaps the ScanGauge woke up, and didn't go back to sleep like it should have.

    This is my best theory about why my battery died after about a week of disuse. I have left it twice as long both before and after; the only unique part about the time that my battery died is that after leaving the car for a few minutes, I returned to retrieve some additional items from it. My guess is that the ScanGauge thought that the car was turned on, and then didn't think the car was turned off again, draining my battery.

    I haven't tested my theory thoroughly by seeing if it's possible to get the ScanGauge to power back on without starting the car, or if doing so will keep it from shutting off; perhaps someday when I'm feeling bored.

    But as others have noted, it's not the solar roof.
     
    #6 macman408, Jun 25, 2010
  7. krouebi

    krouebi 2012 Peugeot 3008 HYbrid4

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    Hi everyone,

    and thanks for your input(s).

    Yes, I did access and close the car from the passenger side, and my headlamp switch is on "AUTO" - but I (or someone else) would have noticed the headlights being on (which they ahouldn't be in bright daylight anyway). So that IMHO is not the reason.

    The SG, however, could very well be the culprit. In both our Prius it is sometimes "on" (the display is lit) even when the car is "off", and you can - in both cars - turn on the SG at any time just by pressing the button with the red circle on it.

    But then again - how much current does the SG draw?? We've left one or the other car for up to 5 weeks, SG connected, with no problems whatsoever, and here we're talking ± 24 hrs. between my opening/closing the car and the totally dead battery.

    In a German forum the courtesy lights behind the sun visors were pointed to as possible culprits - but these seem to be on a "battery preserving" circuit: I checked them this morning after the car had been sitting with the sun visors down for 18 hrs, and these lights will not come on until you flip the sun visor up and then down again. This is kind of clever ;).

    Well, this remains a mystery - I'll have the battery checked as a precaution, and otherwise it just serves to prove that even the best car can have its bad days :confused:.
     
    #7 krouebi, Jun 25, 2010
  8. macman408

    macman408 Electron Guidance Counselor

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    I asked the Scangauge folks that very question; they said about 100 mA when on, and 1-2 mA when off.
     
    #8 macman408, Jun 28, 2010
  9. kgall

    kgall Active Member

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    Kroubei,
    If you'll look at the main forum over the last week or so, you will see that a friend of mine had an experience similar to yours--six days to a dead battery.
    And there are others too.
    Some of us are starting to wonder if there is an issue with the hardiness of the 12V batteries Toyota uses (they aren't as strong as basic US 12Vs--don't know about where you are. Or maybe something odd bug in the system which drains batteries for reasons unknown. A number of folks suggested that I tell my friend to take the matter up with the regional service people. So I did.
    And I might suggest that you raise it with the regional or national Euro-service people.
    If you do, I'd be interested to know what they say.
     
    #9 kgall, Jun 28, 2010
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