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Battery dead after four days

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by GeoffM, Oct 29, 2004.

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  1. GeoffM

    GeoffM Junior Member

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    I drove my Prius about 60 miles last Sunday and then went out of town until last night (Thursday). This morning, I jumped in the car, pressed the Start button, and nothing happened. No lights, no sounds, nothing. I opened the door to see if the interior light would go on but that didn't work either. Totally dead battery. No problem I thought, the car's parked in the garage and I have a small charger, so just hook it up, get it started and go. Not quite so fast...

    Despite many things I've read here about needing minimal power to start a Prius with a dead battery, I didn't find that to be the case. My slow charger can put out about 8 amps and every time I pressed the brake pedal to try to start the car, the current draw went so high it pegged the meter on the charger and wouldn't start. So I walked to work and came back about four hours later to try again. By that time the battery had charged enought to start, and off I went.

    Questions:

    1. What would cause the battery to discharge so quickly? I checked all the interior lights and they were set to "door", so that shouldn't have caused the problem (and the doors were closed). My Prius is a 2005 BC with SKS, but the car was parked in my garage with the doors unlocked so you would think that SKS wouldn't be using much power. I don't have anything plugged into any of the power outlets. What else can I check?

    2. What kind of power will it take to start a completely dead car? I know my slow charger can't do it, does anyone know what the starting current is for the car? Obviously the electric-assist brakes are using a bunch of current, just curious how small a charger or battery would get you going again.

    Needless to say, I'm now incredibly concerned about taking this car to LaGuardia and parking it in the garage for more than a day or two when I go out of town. And not being able to even get the car in neutral without power means it could be really tricky to get a jump parked face-forward (as required) unless someone has really long cables. Even getting the back hatch open to try to access the battery directly from the rear won't be fun.

    Any way you look at this this is not the car to end up with a dead battery, and it's too bad the computers don't work as hard to maintain the SOC on the 12v battery as they do the HV one.

    Geoff
     
    #1 GeoffM, Oct 29, 2004
  2. efusco

    efusco Moderator Emeritus
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    First I'd buy a rechargable 12v jump start kit. Mine has a built in safetly light and air pump that's convinient for adjusting tire pressures.

    Next, you need to have the car checked at the dealer. There is something causeing a serious draw on your battery or your battery has been deeply discharged previously and is no longer capable of maintaining a charge for very long and needs replacement. This is NOT normal behavior. You addressed the obvious things (interior lights in particular).

    I would not have expected your slow charger to be able to jump your car, but probably just 30min or so of charging the battery would have been enough. Some have even speculated that a couple of 6v lantern batteries would be adequate...I'm not so sure.

    Another option that you can consider, but should NOT have to resort to, is a solar trickle charger you could leave your car on while parked (assuming you're in the sun) to keep the battery charged while you're away. But make the dealer thoroughly check first.
     
    #2 efusco, Oct 29, 2004
  3. LungCookie

    LungCookie New Member

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    #3 LungCookie, Oct 29, 2004
  4. bruceha_2000

    bruceha_2000 Senior Member

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    Geoff,
    Is it remotely possible you left the car in ACC or IG-On? Maybe powered off then went to either of these modes to check something, listen to the radio, etc and forgot to power off when you left?
     
    #4 bruceha_2000, Oct 29, 2004
  5. GeoffM

    GeoffM Junior Member

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    Nope. Plus, SKS would have beeped at me and with the car parked in the garage there's no way I would have missed that.

    Looks like I'll be taking Evan's advice and getting the car in to the dealer for a checkup. Arrghhh... 3-week-old Toyota's aren't supposed to be in the shop!!!

    Geoff
     
    #5 GeoffM, Oct 29, 2004
  6. efusco

    efusco Moderator Emeritus
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    Geoff,
    The 3 week old thing is what makes me most suspicious that the dealership, at some point, did one of the things mentioned above and let the 12v discharge completely. Now it's not functioning up to snuff.
     
    #6 efusco, Oct 29, 2004
  7. GeoffM

    GeoffM Junior Member

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    Perhaps, but wouldn't you think an 18-hour drive from MI to NY would have recharged the battery, no matter what the state of the initial charge?

    Geoff
     
    #7 GeoffM, Oct 29, 2004
  8. Frank Hudon

    Frank Hudon Senior Member

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    most modern automotive batterys don't ever recover from a complete discharge. The older lead acid batterys would but the new ones us a larger amout of antimony in the plates instead of lead and this is the problem. It creates a chemical barrier to the transfer of electrons. I could get more technical if you want but that is essentially the bottom line.
     
    #8 Frank Hudon, Oct 29, 2004
  9. DaveinOlyWA

    DaveinOlyWA 3rd Time was Solariffic!!

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    i agree with frank. a battery as small as the 12 volt battery in the Prius i would think would be very weak and not withstand many discharges.

    as far as your trickle charger starting the car, that wont happen. 8 amps at 12 volts is 96 watts. that aint enough to do it. add the resistance of a dead battery and its gonna be worse. realize that power output isnt that cut and dried but it still gives you a general idea of what is needed. to jump a car with a dead battery, you are looking at various levels of charge ranging from roughly 150 amps for short duration charges to maybe 20 amps for 15 minutes of charge. keep in mind that temperature of the battery also plays a part too.

    to boot an average computer can take up to 300 watts if you have an optical drive and multiple hard drives with a CRT monitor and computers use very little power when compared to nearly every appliance.
     
    #9 DaveinOlyWA, Oct 30, 2004
  10. GeoffM

    GeoffM Junior Member

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    So it sounds like you're saying that my battery may have latent damage from over discharge through some event before I picked the car up, and if not, then it has some now because of what just happened? Disapponting to say the least if the battery is that easily damaged, and Toyota did nothing to prevent deep discharges.

    Sure, to bring a dead battery back to life takes sustained power over some period of time, but if you look at some of the other threads on this board related to starting a Prius with a dead battery, it's very easy to get the impression that all it takes is enough current to activate the ECUs, the HV battery relays, and be on your way. Guess nobody really tried it, and as I found out, the brake system is what kills that theory.

    Geoff
     
    #10 GeoffM, Oct 30, 2004
  11. jayman

    jayman Senior Member

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    In the condo where I live, the heated underground parking is secured, so the only driver who routinely sets his alarm is the Mercedes S-class owner. I have noticed that some owners are away a LOT on business, and they have rigged those tiny fully automatic trickle chargers to their car. They're very small and only put out about 1A, but if you're gone for 2 weeks or a month, it will monitor the battery and automatically keep the float charge on the battery. They are guaranteed not to overcharge either. After hearing these horror stories of dead batteries, I may invest in a trickle charger. Companies that make them: Chicago Power Tools "BFC-12," Guest "Battery Pal," Vector Manufacturing "Smart Charger." You can find these neat gadgets at (http://www.automotive-battery-chargers.com). Hope this helps!
     
    #11 jayman, Oct 30, 2004
  12. DaveinOlyWA

    DaveinOlyWA 3rd Time was Solariffic!!

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    that is a good idea. modern chargers have electronic circuitry that prevents overcharging. for long periods of inactivity that might be the solution although that wouldnt help the traction battery.

    the traction battery will hold a charge much longer because it has more charge to hold but it wont last forever.

    does anyone know what a max recommended storage time for the traction battery would be?
     
    #12 DaveinOlyWA, Oct 30, 2004
  13. efusco

    efusco Moderator Emeritus
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    HV battery should be good for 6-12 months untended.
     
    #13 efusco, Oct 30, 2004
  14. efusco

    efusco Moderator Emeritus
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    Geoff,
    Toyota has done many things to help prevent deep discharges. The headlights turn off automatically when the door is open and the car is off. The inside lights turn off automatically after 15 min. if the door is left open (that's saved my nice person several times already b/c my kids like to forget to close the door or fail to close it all the way). The power outlets are not active when the car is off. There's a shut off for the SKS.

    Could they have made it nearly bullet proof...sure, but at what cost. How much frustration with figuring out why the car shut down XYZ system to save the battery. There's no way to make the system 100% foolproof. If some kid who was doing the prep on your car left it in AUX or IG On mode while they were washing it, then got distracted and walked away for 45 min. and came back to find the battery completely discharged how would you propose that have been prevented?

    I'm really sorry you had this problem. But things can and do go wrong, and it sucks when it's you who has the problem. But the best you can do is have the vehicle checked for a short that may have caused the premature discharge. The have them check the integrity of the battery itself. If it is bad then you should insist that it be replaced under warranty.

    Good luck.
     
    #14 efusco, Oct 30, 2004
  15. DaveinOlyWA

    DaveinOlyWA 3rd Time was Solariffic!!

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    thanks for the info. 6-12 months is a long time, although i couldnt see me parking my car long than a few days if that. it will definitely cover vacations and normal trips though. i have friends who live in alaska and new mexico and they would have occasion to let their car sit for up to 5-6 months.

    on the OP, if its just a battery problem then no problem. but seems pretty unusual that a car would drain the battery in such a short period of time without having other problems.
     
    #15 DaveinOlyWA, Oct 30, 2004
  16. DanMan32

    DanMan32 Senior Member

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    When you put your foot on the brake pedal, was the brake pump running, even if it might have been slower than normal? If so, you could probably wait until it reached full pressure, then try powering on.

    Another idea. Press lightly on the brake pedal, only enough to trigger the brake lights. I believe there is some margin before it will kick in the hydrolic pump.

    I also agree, the dead battery itself was a big load too.

    And, unless you have the mod, adding a solar trickle charger connnected to the power outlet won't help, as it is disconnected when car is off.

    Is it possible you left the headlights on? It only shuts off if you power off the car, then open the driver door.
     
    #16 DanMan32, Oct 30, 2004
  17. efusco

    efusco Moderator Emeritus
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    A good point Danman...I have my solar trickle charger hooked directly to my battery via some alligator clamps that came with it.

    It is, however, easy to modify the power outlet:

    http://coastaletech.com/power_outlet_mod.htm
     
    #17 efusco, Oct 30, 2004
  18. GeoffM

    GeoffM Junior Member

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    Really good thought, and I actually tried feathering the pedal when I heard the pump running. I'm not sure I waited long enough to see if the pump would stop and the car would start, but that's a good idea for next time. (Of course I hope there is no next time!)

    And Evan, I agree there's only so much you can do to prevent battery rundown in a car. My confidence has just been shaken a bit by this experience and until I know what went wrong, I'm not going to be comfortable leaving this car parked anywhere for more than a couple of days. Hopefully the dealer can get me in sometime this week.

    Geoff
     
    #18 GeoffM, Oct 30, 2004
  19. efusco

    efusco Moderator Emeritus
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    Can't blame you for that!!
     
    #19 efusco, Oct 30, 2004
  20. DanMan32

    DanMan32 Senior Member

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    After my post, I verified that it is possible, though tricky, to apply the brakes just enough to allow power on to Ready, but not operate the hydaulic pump.
     
    #20 DanMan32, Oct 31, 2004
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