The 12.5 is normal for a full battery, old or new. If the old battery was bad to the point it will not take a charge it would read lower, old or new if they take a full charge they will be about the same. The 13.3 reading you are getting is from taking the reading while charging or immediately after charging, It should read around 12.5 or 12.6 in the morning unless there is a draw on it through the night.
Dale & Terri, Lulu & Tiki (our Chihuahua's), New rescue puppy Prince - Pom/Pug mix.
2013 Tundra, Double Cab, 5.7, TRD Off-Road, 4X4, Full Tow Package
2013 Wildwood T26TBSS - Sold
2000 Gulf Stream Sun Voyager M-8357 MH, Ford Trident V10 Gasser, 35 foot.