Mark;
I use a P-4 as a starting battery and as a possible backup for AHs.
I agree with your analysis that the batteries were not properly charged. The same short life of the warranty set is inevitable unless the charging systems are improved.
AGMs need the 14.4V temp compensated during stage 2 - Absorption, not the 13.6V that many chargers use. I rely on my solar chargers to use 14.4V with temp compensation to get the batteries ready for stage 3 - float. AFAIK, the Boondocker has the 13.6V problem, as do most converter/chargers. 13.6V is an upper range float for AGM specs.
The Enersys(Odyssey, Sears P-?) line of AGMs tip the scale towards high draws over long low draws as far as service category. Their C20 AHs are way under 10% of their CCA ratings. They are popular with the boombox car radio folks(Ick!) for their instantaneous Amps.
IMHO, Deka, Lifeline and Trojan are better for RVing with adequate low draws along with useful potential for high draws.
On a price basis, it is hard to beat the 6V and 12V 100AH AGMs which are now found for $169 at the club stores.
HTH;
John
