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Alternator overcharging?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Danno, Dec 30, 2001.

  1. Danno

    Danno 1/2 ton status

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    My alternator appears to be running at 16V, not 12. The volt meter is steady at 16V, even when I turn on headlights and the blower. It'll drop when I use the power windows, but not below 13V.

    My batteries are getting fried!

    This is a new alternator. I put it on a couple months ago, and it's been doing this since day 1. The batteries are full of fluid.

    Is there some kind of external regulator I can poke at? I was under the impression most GM alternators had internal regulators.

    Argh. If it's not one thing (overheating, see thread in diesel section), it's another.

    1984 K5 Blazer 4x4 Silverado
    6.2L diesel, 700R4, 3.42 gears, 31x10.5" tires
     
  2. 95 Silverado

    95 Silverado 1/2 ton status

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    before you condemn the alternator, double check the voltage with an accurate voltmeter, many alternators will charge as high as 14-14.5 volts, your in dash voltmeter could be reading a bit high, clean the connections on the battery and alternator and be sure the grounds are clean also. a battery that is being overcharged will usually look "wet" around the vents and filler caps from being overheated

    '95 Chevy Silverado 1500
    5.7 V8-NV4500- 3.73 rears
    See My Toys: <a target="_blank" href=http://community.webshots.com/user/wdb172454>http://community.webshots.com/user/wdb172454</a>
     
  3. Thumper

    Thumper 1/2 ton status

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    Take a voltmeter and read right at the battery terminals to see the actual voltage. If its putting out 16V, it will cook your battery and it wont last at all. If the case is that its charging 16V, your internal regulator is shot.

    Mike


    <font color=blue>Thumper
    85 Fullsize Jimmy
    [​IMG]
    <font color=red>Aint Skeered!! </font color=red>
     
  4. Danno

    Danno 1/2 ton status

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    Oh, the batteries definately are looking wet on the top these days. I have had to top off the fluid once or twice using distilled water.

    My old batteries would literally boil over every now and then.

    1984 K5 Blazer 4x4 Silverado
    6.2L diesel, 700R4, 3.42 gears, 31x10.5" tires
     
  5. Danno

    Danno 1/2 ton status

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    I'll grab a voltmeter sometime soon and check that out.

    Rats. Guess I'll have to exchange this alternator for another one. I love warranties! :-)

    1984 K5 Blazer 4x4 Silverado
    6.2L diesel, 700R4, 3.42 gears, 31x10.5" tires
     

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