Assuming you have a standard 120amp alternator, and the stock 8ga charging wire, that's close to correct. 13.2 would be better, but with age, all things "droop"
With the double fans, and having to run A/C, and headlights etc. my load got to be too much, so I upgraded the alternator to a 200amp, and upgraded the charging wire to 4ga.
Now, with everything running full blast it never drops below 13.7 as reported on the aldl data stream. No load, it runs 13.9-14.0