Alternator Voltage Output: 2001 5.3

I was wondering what you all see for your alternator's output. I had a 105amp alternator and it usually stayed at or just above 14 volts.

I installed a new 145 amp alternator and it is at 14 volts just after startup then it goes under 14 (like 13.5 volts).

Is that normal range? These are internally regulated right?

Mine typically stays right at 14 too, and it's stock. I think I remember it going higher when I was jumping somebody, but that's the only time it's ever changed.

No problem as long as it keeps the battery charged and carries the load at 1K rpm with everything turned on.

Also a dash gauge may be off a little bit.
Put a volt/ohm meter on battery for a true test.

Typical alt output as measured at the batt terminals should be 14.2 to 14.7 volts. Use a digital VOM to check it.

Ok, I will put my Fluke on it and see this evening. I notice at startup it is usually just over 14 but once the truck warms up it is below 14 (by the dash gauge anyway).

your output should stay about the same, but it can handle much more load.

your output should stay about the same, but it can handle much more load.

Thats what I thought: maybe when i load it up it would climb, but it doesnt.
I have a 6 headlight setup (hi/lo/fog), 6channel amp, AC on, interior lights on and the volts kind of get lower as everything gets turned on.

I thiink this one was wound kind of weak. It was listed as "NEW" Factory take-off, now I know why they took it off :banghead:

Kind of like snakeoil:popcorn:

Well I have another one coming so I will know for sure.

You might as want to check check the base battery voltage.
As long as charging voltage is over battery base voltage and battery stays up good and it carries all of the load when running it should be good.
With a good battery alt tester.
Run a pile load test on it and see if it is putting out full amp at 2500 rpm.
Older ones the charging voltage was in the 14.5-14.7 volt range.
Newer ones you are doing good to get 14 volts.
If I see 1/2 to 1 volt over battery voltage I call them good.
MT

Older ones the charging voltage was in the 14.5-14.7 volt range.
Newer ones you are doing good to get 14 volts.

MT

So the newer alternators are regulated lower, is that what your saying? Why would they do that? Is there a way to adjust the voltage?

No, you cannot adjust voltage. Remember, 12.6 volts is standing voltage on a fully charged battery (2.1v/cell, 6 cells). The specified alternator output design is 13.8 volts - this is what your vehicle electrical system tries to maintain. There are a lot of computerized systems on these vehicles, from the airbag system to the radio and including the PCM. These aren't very tolerant of overvoltage, so the regulators are tighter now than in the past.

14 volts in my opinion is still a little high for alternator output on a system with a fully charged battery, 13.5-13.8 is nominal operating voltage. MT nailed it when he said charging output .5 volts higher than nominal battery voltage is good - it means the system is operating as designed.

To sum it up in 5 words -

There's nothing to worry about.

A higher voltage might make your lights brighter and your amp a little louder, but it will also shorten their life. It will also shorten battery life, especially if you have an Optima battery.

Thats what I thought: maybe when i load it up it would climb, but it doesnt.
I have a 6 headlight setup (hi/lo/fog), 6channel amp, AC on, interior lights on and the volts kind of get lower as everything gets turned on.

I thiink this one was wound kind of weak. It was listed as "NEW" Factory take-off, now I know why they took it off :banghead:

Kind of like snakeoil:popcorn:

Well I have another one coming so I will know for sure.


Did you find a kit for the 6 light or how did you do it?

I added a set of Bosch Relays. It was a kit from Mrtaillight on ebay I think. Let me see if I can pull up the item #.

Here it is:
ebay Item number: 200086509713

**HINT** He will take $16 + Shipping when you submit best offer. If you look at his auctions for these, some of them are priced much higher for same item, if you search through you will find them much cheaper, then submit best offer.