Volt Meter?

[camper4lyfe]

So what exactly IS the volt meter gauge showing me?

I've noticed recently that it fluctuates a lot, especially once my truck warms up, and the idle drops.

I've got an 03 FX4 with the 4.0L 6. I tested the battery this morning before I started it, and it showed 12.2V. When I started it, the volt meter was sitting pretty right in the middle of the gauge.

I got to work, and at idle, the needle on the gauge drops to the bottom of the battery on the gauge. I tested the voltage at the battery, and got ~13.4V.

If the gauge is dropping, but the voltage remains mostly constant, what is it actually telling me? I know this is the original battery, and I'm on borrowed time with it...is it actually the battery losing voltage, and that's what the gauge is telling me? I'm quite confused.

 

[kimcrwbr1]

http://www.therangerstation.com/tech_library/chargingsystem.htm

Read tihis all the way through and follow the test procedures for the internal regulator in the alternator. You will need to pass both the load and noload tests or you can burn all three up bat,reg and alternator.

 

[camper4lyfe]

Thanks for that, but that didn't answer my question.

 

[4x4junkie]

It's a relative voltage gauge (I say relative because it's got little in the way of scale markings on it).

At the battery (fully charged) you should have approximately 14.4 volts with the engine running above idle (it'll be a little less on a hot day, more when it's cold out). With the engine off (after sitting overnight) the volts should be around 12.7.

At idle, the alternator's output is at it's lowest, so things like the blower fan (especially if the headlights are on) are more likely to cause the volts to drop down to that of the battery itself. This very often is the case if you've installed something like an underdrive pulley on your engine.