We have a 2003,has a hard time starting,have been charging frequently,battery tested good,a AR2battery reading came across today, what could it be?

I was having this same problem with my 2004 Suburban Z71. The battery tested good (several times), the alternator tested good, would not have ANYTHING plugged into the outlets when I parked and yet 3 or 4 times a week it would have to be jumped to start. I mean it would be so dead that it seemed to take FOREVER to get enough juice to it to finally start. I thought the same ... "something HAS to be shorted and draining the battery". I ended up buying a $250 deep cycle marine battery (the one with the blue top and a set of cable converters to go from the factory side mount cables to a top mount battery) and have not had a problem since! I'm not saying you need to go to that extreme, but even though the battery tested good, a new one with a little more "umph" or cold cranking amps would probably do the trick.