More Battery Drain Discussion

[baby huey]

I recently purchased a high-quality portable battery charger/maintainer. To my surprise, whenever I charge the battery it always starts @ 25%, and slowly works its way to 100%. This occurs even after driving the vehicle for an hour at freeway speeds. As a comparison test, my 2005 4Runner, with the original battery and rarely driven, always starts charging at 75% and rapidly goes to 100%.
I’ve discussed this with the local Service Rep. She said there’s a lot of continuous draw on the battery when the vehicle is parked, and further, the alternator is programmed to not start charging the battery after starting for the first 20 minutes or so. Regardless, it should be charging above 25%!
My concern is twofold; one, if the battery is in fact @ 25%, it is close to being discharged and therefore may fail to start the car someday. And second, with the portable battery charger repeatedly bringing the charge from 25% to 100%, this has to be destroying the battery through excessive cycling.
I’m tempted to have the Dealer do a load test on the battery and also check the alternator.
Comments?