Author Topic: charging  (Read 2076 times)

Offline mikes85

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charging
« on: September 13, 2014, 11:38:49 pm »
hello everyone i have a 85 silverado c30 1 ton 454.74000 original  miles i got the truck and had to put a starter on it ran great about 2 weeks later i noticed the needle on the gauge was really low so i bought a  alternator from auto zone put it on and the needle was back up to around 14 volts well around  2 months later i noticed the needle was going back down again so i headed back to auto zone and he tested it and says ok  i will get you another one ok cool put it on and the needle didnt go up was on about 8 volts so ok new battery so got a new battery which it needed one anyway so put it in and still was only at 8 volts.now if i charged the battery on my charger it would still only show around 8 volts but i could drive it and do what i needed to do as long as i didnt use the headlight then it drained faster of course.called my brother  and he had one of those hand held tester it shows the alternator is putting out 12 volts he tested the battery also 12 volts he pulled off the positive cable and tested what was coming threw the cable from the starter and it was 12 volts but when you pulled the positive off the battery the needle went  straight to 15 volts as was the battery or the cable. then when you put it back on the battery it would drop down to 8 volts and if you turn on the headlights the needle dropped  pretty much to zero and on the battery it would drop to as low as 6 volts. now that alternator that is on it is 63 amps according to Chevrolet that year with the 1 ton 454 should  have a 78 or higher amp alternator there is only 15 amps between is that enough to cause all of this is it possible that the new  alternator just aint putting out enough to keep up with it lol thanks sorry its such a long story lol

Offline bake74

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Re: charging
« Reply #1 on: September 14, 2014, 10:42:24 am »
     First off welcome to the site.
     Long stories are OK, in fact we like stories and love pics.  But in the future break them up into paragraph's for ease of reading and you will get more responses to your questions.
     Having a lower rated alternator then what is required is a problem, but might not be all your problem, or could be.  That should be the first order of business you take care of.  Here is a direct bolt in upgrade to a 95 amp alternator done by one of our members.  (if you don't know, the green wording is a link that will open the page )
     This should be your first course of action.  I know you bought a new one, but it is under powered for your truck.  Once you do that and it does not solve the issue, we have in out tech section all the manuals and wiring diagrams for our trucks, and a whole lot of members with an extensive background in these trucks that will be more than happy to help you out.
      My one concern is when your brother took off the + cable and your volt meter showed the correct voltage, my concern is that you might have a short in 1 or more of your fuse-able links or wiring that is on the positive cable circuits.  But like I said, take care of the alternator first to eliminate that problem out of the equation.
#1: The easiest and most obvious solution to any problem is 99% of the time correct.
#2: There is no such thing as impossible, it just takes longer.
  74 k10, 77k10    Tom

Offline mikes85

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Re: charging
« Reply #2 on: September 14, 2014, 12:49:53 pm »
ok great i will do that first thank you