Where does your volt gauge sit? (1 Viewer)

[Zack1978]

Hi everyone,
I replaced my alternator about a month ago with a used alternator that I had in my parts stash. The other alternator was having some voltage spikes, so I figured I would just replace it.
So far I have not had any issues with the new(used) alternator, but I am wondering where your dash volt gauge sits. I "think" my gauge is reading lower than it did with old alternator. I have no idea how old my used alternator is, or if it was ever rebuilt.
I took three separate pictures of the gauge.....

1. full load (headlights, both heaters, and radio) at highway speed
2. full load (headlights, both heaters, and radio) at idle
3. No load at idle

How does my gauge position look?
I am thinking that my new used alternator might be putting out a low amount of power. Again I have NO history on the alternator.

Thanks,
Zack

PS: I realize that the dash gauge is not 100% accurate, but it is the best game in town at the moment.

 

[Zack1978]

Picture # 2

 

[Zack1978]

And finally # 3

 

[Jesper]

That's about the range of where mine sits, although mine seems to vary output at random - not really based on load or speed, sometimes its at about 13'ish, others at 11, and if the idle is really chugging like first thing in the morning it shows real low (9/10) til I get the RPM's up.

Anyone else care to opine on what normal should look like?

 

[micruz60]

13.9 with all accesories off, engine warmed up, idling at 690....
With headlights, heaters, wipers, and going down the road, 2500 rpm... Around 12.5 or so.
Make sure the wiring connex are clean, snug and contacts are good. Chasing grounds is no fun, and corrosion hides inside the wire sheathing. Good to check resistance in wires, replace those with too much.

Add... Make sure the belt tension is not too loose or too taut.

 

[RBA]

Not sure if this will help you but here goes...

I recently installed a "high output" alternator after noticing that my voltage would drop below 12V when I had my lights, AC and stereo on. I installed the new alternator and still had the same voltage issues. At idle ~12.6, at 1100 RPM 13.4, topping out at around 13.7. I called the manufacturer and he immediately said I have 2 issues. First the pulley is too small and I would need to replace the pulley so the alternator spins quicker at idle. Second, my ground is not good enough. I should replace my "main" ground or at least double up.

I purchased a 12 inch ground cable and attached it from the battery to the main ground point. My voltage at 1100 RPM is 13.7 and over 2KRPM I'm 14.2. So it made a difference. I still need to do something about the pulley...

 

[sgiandubh]

It might be worth checking the alternator output with a voltmeter at the battery. Your gauge could just be reading low. The cheapo voltmeter that I have (installed by PO) reads lower than my dash gauge.

FWIW, I have 62 gauges and a chevy alternator but mine never drops below the mid-line no matter the condition. Here's a pic AC and lights on the way to work this am. ~1700 RPM

 

[Zack1978]

What specific grounds should I be looking at/checking?

 

[Output Shaft]

The ground from the batt neg post to the body.. a few inches away. If in doubt, scuff all the metal and replace the bolt with a shiny one.

My voltmeter gauge needle used to sit midway between 12 & 14 when the car was newer. The needle would be above the 12 entirely. Drop a little with headlights on at idle.

Now the needle sits at the top of the 12, covering it up a bit.
Measured volts at the battery are fine: 14.1-14.3V with new alternator.

I just attest it to the degradation of the dash meter over 30 years.

Get a good hand held volt meter and calibrate your dash gauge against it. Where the needle sits isn't all that important. Being consistent is.

 

[brian]

First the pulley is too small and I would need to replace the pulley so the alternator spins quicker at idle.

you would need to reduce the alternator sheave size, or increase the diameter of the crank sheave.
a larger dia on the alternator, would slow it's rpms even more.