Battery Alternator wiring issues

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by SkyjackerK5, Feb 25, 2003.

  1. SkyjackerK5

    SkyjackerK5 Newbie

    Nov 23, 2002
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    I've been adding a lot of accessories and I have been attatching them to the battery junction block. I noticed my voltage going to crap when the truck is running and now my battery is completley dead. Why is the battery being effected and being drained when it should be getting charged while the engines running. Bad or tired alternator?
    I did replace some wiring when I replaced the engine, could this be the problem? /forums/images/graemlins/k5.gif
  2. imiceman44

    imiceman44 1 ton status Premium Member

    Aug 5, 2002
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    Sacramento, CA
    Could be one of 2:
    Either the total consumption for the accessories you added are more than the alternator can top off,or
    The alternator is going to the craps.
    Could be both too
    You need to have an ampmeter hooked up to see what is the draw on the battery. then check what amps rating your alternator is, and replace with adequate.
    If you add more info on vehicle model year options and what you added, we could help you better.
    Also if you fill your profile with this info as well as your location, there might be someone close by that is willing to give you a hand.
  3. Ryan B.

    Ryan B. 3/4 ton status GMOTM Winner

    Jul 18, 2001
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    It could be a bad battery as well.
    I had a bad battery and it ended up taking out the alternator as well so i had to replace both within a day of each other. /forums/images/graemlins/shocked.gif

    Take a baseline voltage so you know what your battery is at, say 12.4.
    Then start up the truck with all other electrical accessories off. Check the battery voltage again. It should be like 1 volt higher, maybe 13.4 volts. This tells you the alternator is doing its job.
    Then turn on all your electrical accessories, headlights, heater, radio, windsheild wipers, everything.
    Check the voltage again. You should have at least .5 volt (12.4 + .5 = 12.9) above your basline voltage left over to charge the battery. If it is lower than that, this means you have to many accessories draining your batt. and your alternator can't keep up because it isn't putting out enough amps.
    /forums/images/graemlins/thumb.gif /forums/images/graemlins/k5.gif
    Good luck.
  4. Skigirl

    Skigirl 1/2 ton status

    Apr 2, 2001
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    Los Angeles, California
    In addition to what the other guys said, you didn't mention that when the truck is running that you are using all those accessories. If not, then maybe you are getting a battery drain. It's worth checking. I had a drain that killed off a new battery in a matter of a week or so. Pull the neg (or pos) cable off the battery, hook up an ammeter to the battery terminal and now disconnected cable and check amperage. If you have more than 32 (IIRC) milliamps, then you have a drain. Make sure your doors are closed and nothing else is on. Sorry if this is too elementary a post, but I didn't know how much you knew about electrical stuff.

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