On Mon, 17 Aug 2015 11:47:31 -0700 (PDT), Tim
wrote:

AGM Greg. That's why I said "dry" because that's a common term for them. The gel cells will slowly leak when punctured.
But that's rare. I'm sure they're around, but gel's aren't popular in my area.

===

Both gel cells and AGMs are somewhat more finicky about how they are
charged. That said, I've switched over to AGM starting batteries on
the big boat. So far, so good. Almost two years and several major
cruises and they still seem to be going strong. I've made no changes
to the voltage regulators. Previously each engine had a single 8D
starting batt. I replaced them with two Group 31M AGMs in parallel
(Sears Platinum DieHards). The combined AGMs have more cold cranking
power than the single 8D, are much easier to change out, and so far
seem to be more durable. THe only downside that I can see is that
the AGMs will be more difficult to source in the boondocks if that
ever becomes necessary.