Alternator/Charging Voltage Questions

[spoonfedblue]

So I have this '06 F250....what I'm noticing is that randomly my charging/battery voltage(as monitored by my Insight CTS) will drop to almost 12.5V. When it does this it stays that way (12.5-12.7v) until the truck sits for a while, usually overnight. For example, today after work (sat all day) I fired it up, waited for the glow plugs and saw my voltage go up to about 13.6v. Kick in high idle and it goes up to 13.8v-14.0v. Drive the 20 miles home, all looks OK, around 13.5v. Get home, shut it off, and it sits for maybe 15 minutes. Go back out to run some errands, and after my glow plugs shut off, my voltage shows 12.4v and barely breaks 12.8v once I start driving. Also when this acts up and I flip my high idle on, it starts ramping up almost immediately, to 1400 rpm or so. Normally it just sits at 1200.

So that's what's going on. I think my alternator is on its way out, but it doesn't seem to be hurting the batteries. I replaced them 3 weeks ago or so, and it still starts just like it did they day I put them in. No battery light either.

Any thoughts guys?

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[dfuzz78]

Batteries normal voltage at rest is 12.3 volts +/- so I'm curious as to why you are worried about your voltage/alternator when it never drops below resting voltage...

If you are concerned about it that much, just replace your alternator with a new one from MotorCraft or DC Power.

But until your battery light starts flickering, (bad voltage regulator) I wouldn't worry about it.

[spoonfedblue]

The only reason I'm looking at it is because it never seemed to do that before. But it's possible I never noticed it before. Just don't want to kill my new batteries or wind up stranded somewhere that's all. Truck never acts like its having a problem, so I'll rest easy until it does. Thanks for the reply, sometimes we just need to hear it from someone else I guess!

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[ZMANN]

I think you have a diode going personally they can fluctuate between normal and low

eventually the Charge light will come on


the bummer is they can test fine ,,, but as always clean inspect everything cable wise