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Old 08-10-2010, 04:55 PM
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Running engine volt charge reading goes down

Hello guys I have something going on with my charging system on my 96 chevy s10. I have a 350 SBC in this thing carbureted and no electronics except my HEI distributor and basic factory stuff and no emissions hookups or anything else.

I have replaced everything on the truck since I got it with a new battery that is only 6 months old and the alternator is brand new as well. Also all battery wires are new as well from positive wire to all the ground wires. Ok here is what's going on. When first starting up my truck its charging at 14.6 volts and will stay that way for a while. Then after a certain amount of time it will go down to about 13.6 but no lower.

I have checked everything with my volt meter and I am not understanding why this is happening. This happened with the alternator that I got new from last fall and I had problems with it vibrating really bad at higher rpm's and breaking the bolt twice that goes into the cylinder head. I brought it too the auto store and they replaced it with a new one and it is still doing this.

That was not why I brought the alternator back but the previous one you could hear the bearings grind in it which was causing the vibrations at higher rpm. I have two volt gauges one being the original factory one on the dash and a mechanical gauge set I have. Factory one always reads less but I am having no problems with charging running power accessories etc for the time being. I am running a 65 amp alternator if that helps.

Now this happens with me running nothing power wise and if running my lights it goes down just a hair but lights are still nice and bright and checking my battery with vehicle not running its always about 12.6. So is this normal as engine has got good and warm? Belt is nice and tight and everything checks out good as far as my hookups goes. Have been told if everything is working good then don't worry about it but I guess I want to know is this normal.
Thanks Eric

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Old 08-10-2010, 05:35 PM
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I'd be a little concerned about the 14.6 as well as the 13.6, should be 13.8 to 14.2. It's probably either a variance in your voltage regulator, or in the gauge(s). Have you checked it with a DMM, to be sure your gauge(s) are accurate?
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Old 08-10-2010, 05:42 PM
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Yes I did check this will a volt meter and what I am assuming you mean by DMM ( digital multi meter ? ) what I mean by volt meter is a voltage meter that checks all different type of electrical voltage from automobile, home use and many other things.

I am new to using one of these but hooked it up and it comes out as I stated above. The factory gauge is a little off but my mechanical gauge is dead on and read's the same as the the hand held digital multi meter. It starts off about 14.6/14.5 then goes down to about 13.6 after its been running a while.
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Old 08-10-2010, 06:14 PM
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Its supposed to drop down, after your battery gets charged back from the power it used to start the car....your alternator charges it back and your voltage regulator cuts it back when it needs to.
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Old 08-11-2010, 04:30 PM
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Ok thanks for the info. I did not know it would do that so I am in good shape then since it's all charging normally. I guess it might have did this all this time and I did not notice it.
Thanks guys
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