I have seen it as high as 14.3, but lately it's been between 13.8-14.0. Though I do run the AC on recycle and full blast since it is hot here in Houston. I have recently replaced the alternator due to it not charging the batteries. I do have an aftermarket sound system, but I don't blare it every where I go. I do notice that when I turn the AC to low it bumps the voltage by (.2) or (14.0). Also lately I have notice some corrosion build up on the negative terminals and some on the positive terminals. I recently cleaned with with the baking soda/water mix which was a damn mess. Anyways I am wanting to see if I may be having an electrical charge problem or my alternator is just a POS which is from O'Reilly's.

 

Mine is about the same as yours but it can go as high as 14.5.

 

Not sure I understand. Are you asking if the numbers you listed (quoted above) are a problem? If that's the question, then you're fine. Numbers will vary from truck to truck, but those are well within normal parameters.

Stewart

 

You mentioned some corrosion on the terminals, a good place to start cleaning. Wire brush inside the clamps and the battery posts. Then coat with NO-OX or equivalent. I am betting that you will see some improvement.

 

 

I usually see 14.2 to 14.4 for about a minute after i first start the engine, then it pretty much holds steady at 13.8-13.9

We just drove 1900 miles cross country towing the 5th wheel and thats what it was with ac maxed, truck and trailer lights on, stock radio, and 2-5 cell phone or tablets being charged

 

I get 14.25V constant. If I put the A/C on and blower motor on high I drop to 13.92V.

 

You likely have a bad glow plug circuit, unless you leave it KOEO until the GPR times out before cranking. Any time the glow plug relay is on while starting (the first few seconds to a couple of minutes, depending on engine temperature), you won't see much over 12 volts.

 

True.
I guess that i should have mentioned that's with the current temps like May - September ish. When the temp is below 60 or so when the glow plugs actually come on then the voltage stays lower for about 5 minutes

 

Your voltages seem fine. How much drop you see from running the AC and other stuff depends on where the gauge is connected so you can't exactly compare to other vehicles unless they're wired the same way. After neutralizing/cleaning the surface of the terminals you should disconnect and clean the contact surfaces. Then add a protectant to reduce future corrosion. Those felt discs you slide onto the posts help keep acid from coming up and attacking the cables & terminals.

 

If you're above 13VDC on a H-O-T day with the system loaded then I consider that okay. If it's dipping close to 13VDC then I would be checking connections (battery and ground) to make sure they're clean and solid. Unless the battery light comes on you shouldn't have anything to worry about since you've got a new alternator IMO.

 

Ok thanks for the replies. The lowest I have seen it is 13.8. Before I replaced the alternator it would not get above 12.5v hence why I would have a dead battery on start.

 

I've been using Vaseline for almost 60 years now and never had a corrosion problem. Also still using the same terminal clearner I bought at Pep Boys for almost 55 years. One side clean the inside of the cable connectors and the other side cleans the battery posts. This one goes for $1.73 which is probably less than I paid for in in 1964 and looks identical.

https://www.jbtoolsales.com/performa...xoCqVIQAvD_BwE

 

BTW, I run between 13.7 and 14.3V after starting which usually pulls it down to 11 or so for a few seconds.

 

Eugene's been using vaseline for over 60 years and his voltage is still up!!!

LOL

Love this forum!!