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drained battery

Discussion in 'Technical Chat' started by vdub, Jul 25, 2010.

  1. vdub

    vdub [OP] New Member

    Joined:
    Jul 25, 2010
    Member:
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    Male
    Vehicle:
    2003 toyota tacoma
    i have a 2003 tacoma
    over a two wk period the battery slowly drained
    having to try a little harder to turn the car over every time i started
    the truck until it wouldn't start at all. i got a jump and it was like a had a new battery... for about a day. then over the last wk the process repeated.

    so my question is this,
    is it the alternator or is the battery just old
    (i mean the battery is old but seemed find up until a month ago)

    to find this out i'll need to get truck started then disconnect the battery and see if it continues to run, yes?

    can i even do that on the tacoma or is there a kill switch that kills the vehicle when the battery is disconnected?

    any input on any level is valued

    thank you for your time
     
  2. tacomaman06

    tacomaman06 Carolina Alliance: Lead, follow, or get the hell o Staff Member

    Joined:
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    Will
    York,South Carolina
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    '13 Silverado ext cab
    if the battery is old....like 3 or 4 years(i've seen newer ones do it as well).......its probably got some cells that are dead/dying. if its that bad....alternator will over charge the battery trying to compensate. get the battery checked at autozone. also....as hot as its been everywhere...and we dont know what state you are in......the heat will killa battery too.

    welcome to tw.
     
  3. larryde09

    larryde09 Well-Known Member

    Joined:
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    Larry
    Rochester, NY
    Vehicle:
    (Traded-in) 06 2.7L 5-spd SR5 4x4
    K&N Intake, Magnaflow Cat-back Exhaust, Altezza Tail Lights, Pop&Lock Tailgate Lock, Extang Trifecta Tonneau Cover, PIAA foglights with stock switch, DrawTite Hitch, OBX Shift Knob, Hood Protector, Vent Visors, DIY step bars/sliders/running boards, DIY Bed Lights, DIY Running Board/Ground Lights, DIY Tailgate Electrical Box (12V socket, voltage and current gauges), DIY Internal Lighting (coming soon), Aftermarket switches in stock dash blanks, Sony Head Unit, Illuminated 4x4 switch mod
    x2....get the battery checked first, 6 years is about all you'll get out of them and could be less depending on the number of times you deep discharged it, amount of load (e.g. accessories), and the climate you drive in.

    During that 2 week period, were you driving the truck or was it just sitting there? It's possible the alternator is dying and not able to keep the battery charged up.

    In theory the car can run off the alternator alone, but I'm not 100% sure. The battery acts as a capacitor too by helping sustain the 12V level during heavy loads. In other words, the alternator may put out 12V under no load, but without the battery, the loads on the alternator may bring the voltage below 12V and the system may not work as expected.

    However, one way I've debugged the system it in the past is as follows: With the truck off, unplug the alternator from the battery, measure the voltage of the battery, start the truck for a few minutes then shut it off. Measure the voltage of the battery again...you'll notice that it is lower than it was before because the alternator was disconnected and not charging the battery. Now, plug the alternator back in, start the truck and measure the battery voltage...if the new voltage is higher, this indicates the alternator is charging up the battery and therefore the alternator is probably ok. Finally, shut the truck off again and measure the battery voltage again...did it go up or is it still down? This indicates that the alternator tried to charge the battery, but the battery did not charge up due to old/bad cells, etc.

    If you suspect the battery, take it to get tested.
     
  4. vdub

    vdub [OP] New Member

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    you guys are great

    thanks!!!!
     
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