Delay in charging voltage

[turbo347stang]

I have noticed that when I first start my truck for the day or I let it cool completely my voltage reads low 11.7ish for about the first 90-120 seconds the truck is running and then it will jump up to the correct 13.8-14.2. Is this common on these trucks? Does the alternator not put out charging voltage immediately?

Just not something I am used to seeing in my years of gas engine work.

[jluv]

Mine does this as well.

[greasyF250]

The lower voltage reading is the glow plugs being on for the 90-120 to help the truck to run smooth and cleaner when cold. This is normal , when the glow plugs shut off , the voltage comes up. Being able to see this in your ammeter gauge ,means your batteries are getting weak. I put in 2 new batteries and have not seen this in 2 years since .

[Austin G]

^^ What he said.


Sent from my iPhone using Autoguide

[jluv]

Mine does it even with two brand new batteries. I don't think it's anything to worry about. I get the voltage reading on my SR7 display.

[turbo347stang]

Originally Posted by greasyF250

The lower voltage reading is the glow plugs being on for the 90-120 to help the truck to run smooth and cleaner when cold. This is normal , when the glow plugs shut off , the voltage comes up. Being able to see this in your ammeter gauge ,means your batteries are getting weak. I put in 2 new batteries and have not seen this in 2 years since .

I hope this isn't the case because I knew one of my batteries was weak so I replaced both and I still see it. The glow plug info makes sense though.