Electrical problem, battery drain. How much is too much?

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by aero, Aug 15, 2012.

  1. aero

    aero New Member

    My battery has been getting weaker and weaker and there was something that was draining my battery (12.7V upon shutting down to 11.3V within an hour or so and continuing to drop). Nothing new has been installed, I do have an aftermarket alpine radio with the factory beeper thing and amplified antenna. The truck does sit more than it had in the past, being driven more like once a week instead of 2-3 times a week.

    Truck is 2005 Silverado 2wd, manual HVAC controls. I havent had any of the speeds go out on the controls (ref the blower relay problem).

    After confirming that there is a battery drain, I checked the fuses and found the following fuses pulling power while the truck is off.
    TBC Bat(10A) - 54 milliamps
    HVAC/ECAS(10A) - 45 milliamps
    RVC(10A) - 34 milliamps

    I left those three fuses out overnight as well as unplugged the blower relay under the dash and there was minimal drain on the battery.

    Does anyone have any idea what acceptable numbers are for those fuses when the truck is off? I know the TBC fuse has the gauge cluster and radio on it, but not sure how much power that stuff should be pulling.
  2. RayVoy

    RayVoy Epic Member 5+ Years 5000 Posts

    They are not high drains, but maybe enough to pull down the battery.

    A lot of modules will continue to draw current after the key is off, they require a little time to "fall asleep". How long after the truck was turned off, did you take the readings?
  3. aero

    aero New Member

    Those readings were taken within an hour of shutting it off and again after sitting 12 hours.
  4. dipstick

    dipstick Member 2 Years 100 Posts

    Milli amps will not do this.
  5. bazar01

    bazar01 Rockstar 100 Posts

    That is only a total of 133 milliamps or 0.133 amps. Not high enough to drain a battery within an hour.
    You can even go up to 200 milliamps and not have any battery issue for a week.

    Say you have a 40 Ah battery, theoretically, for a 1 amp load, it should last for 40 hours. (realistically, maybe 20 hours)
    For a 0.133 amp load, it should last for 300 hours. So it should not drop within 1 hour.
    Have the battery load tested at your nearst auto parts store.
  6. Pikey

    Pikey Moderator Staff Member 5+ Years ROTM Winner 5000 Posts

    I know that this is not related to your draw with the fuses that you specified, but if it has lighted mirrors on the visors I would take a look at them. I have seen the hinge break and let the lights stay on all the time. Hard to see them if you are not in a dark garage with all the lights off and your interior lights off.
  7. aero

    aero New Member

    I'll have the battery checked out...was hoping to not have to replace it. Guess I'll also get another lead for my battery tender to make sure it stays healthy.

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