The very first time I did a technical article on batteries (12 years ago), the AGM's were just trying to break into the marine market (they have a very long history in military applications: jets, helicopters, tanks, etc.) The mil specs on these things were hard to believe (surviving a three meter fall & a 45 cal round).
Unfortunately, the only US manufacturer at the time didn't take me seriously when I inquired for additional information. I was specifically interested in charge voltage requirements and life-cycle data. Subsequently, I went to press declaring, "I can't recommend AGM's at this time, until further information becomes available."
Well, about two weeks after the article hits the streets, I get a call from the president of Lifeline Batteries. In another week, I get a PALLET of batteries delivered to my door. After two years of hammering the crap out of these things (in my vehicles, in two different boats, and in my remote-cabin application), I can whole heartedly recommend them (in fact, I published a retraction on my first impression.) Nearly all of the batteries I tortured 12 years ago are still in service today.
There are no special charge restrictions on AGM's.
PS: The Optimas (Spiral wound AGM's - looking like a large shrink-wrapped six pack), while adaquate for vehicle installations, are NOT the best AGM available. My first choice would be a Lifeline, followed by an East Penn (private labeled for West Marine), ESPECIALLY if you have a monster stereo or do aggressive off-roading.
