Alternator Question

I’ve been having issues with my charging system and tested out the alternator. I read 13.5-15 volts is about what it needs to be putting out. Mine is a border line at 13.64. Is this something I should be concerned about or is that ok? FYI, I did have ac and radio on.

 

No, it's good.
Battery maybe or corroded cable.

 

How did you measure that output value?

 

Do you mean VOLTS? Cause the Alternator puts out far more AMPS than that.

 

Yea meant volts. Just bought a new battery and not trying to get stuck again lol.

 

Take it back to where you bought the battery and they should check your system for free.

 

Standard lead acid like the OEM battery, or an AGM? Some AGMs require higher charging voltage than what the Smart Alternator puts out (over 14 volts). Your 13.64 sounds fine if you are running the normal type of battery. And like I mentioned, it is a smart alternator so it can vary output based on needs.

 

you meant volts.
it will vary based on engine compartment temperature, battery condition etc..
you don't want to see over 15 but you can see as low as 12.75 on a very hot day at a stop light (no air flow cooling compartment).
typical is 14+ when starting and settling to high 13+ as you warm up and battery is holding charge.
it sounds like yours is fine.

expect a small drop if you have headlights and radio on, for example
hook up meter to cig lighter or whatever and watch voltage variation as you drive around to get a feel.
...or you can monitor OBD2 battery voltage but that is overkill if you are unfamiliar.

 

Thanks all for the knowledge. Appreciate it

 

While engine is running, mine is 13.4v to 13.7v, no issues. If it's around 12v or less, (while engine running) then you have a problem.

 

Pardon my ignorance--based on what I learned, if you are measuring the voltage with the alternator connected to the battery you are measuring the battery voltage. Did I miss something? Maybe the OP measured the voltage output of the alternator with the battery disconnected?

Of course, the internal resistance of the battery, plus the resistance between the battery and the measuring point, multiplied by the current being supplied by the alternator will add to the voltage reading, but that should be small.

 

You test the alternator by measuring the battery voltage when the engine is running.

 

applying ohm's law, simple as it is, in this situation just over complicates things. the battery is charging when the voltage supplied to it by the alternator is above the battery voltage at rest.
what the battery is seeing is really what you want to measure. and that can vary as the battery charges, temperature changes, battery loses ability to hold a charge, etc.

btw OP: since you have a new battery, now is a good time to record the battery/charging voltage at various times like before start (after sitting all night), right after start, on a hot day, on a cold day, driving vs idling, etc. In time you will have something fail and having a baseline can be useful to diagnose.

 

Actually, it doesn't matter where you check the voltage, at the battery or anywhere else, you are checking the electrical system voltage. With the engine off and allowing a few minutes for the truck electrical system and the battery voltage to come to a resting state, you should measure around 12 volts or slightly more (less than 12 volts is a bad battery). After cranking the engine, the electrical system voltage should climb to 13~15 volts for a properly operating alternator. At this normal state of elevated voltage, the alternator is pushing amps into the battery.