T&T: Ramifications of AGM batteries

[Bob Frenier]

Candy Chapman & Gary Bell wrote:

 

<snip> AGM batteries accept and release charge significantly faster than
flooded cells, allowing high rate / shorter charge cycles and heavier short
term discharges without problems.
 
Reply: The recent battery posts made me wonder if the ramifications of the
AGM's ability to perform as stated above have been fully explored by the
list, despite a pretty long conversation about AGM's over the years. In
other words, would being able to quickly store a LOT of juice change our
perception of what is possible electrically on our boats, including how big
a battery bank we could handle?
 
For example, as Arild and others have pointed out, large frame alternators,
properly regulated, can dump large amounts of energy into an AGM battery
bank quickly. So how does that affect our perception of the overall
usefulness of ac generators, which I believe have inherent bottlenecks when
creating dc energy (not revealed when using slow-charging batteries), but
which have previously been the only reasonable way to capture continuous
power for big loads? Also, where might the genset discussion lead our
thoughts about the size of wing engines, if they could be properly loaded up
with alternators to surge energy into a big AGM bank? 
 
Similarly, AGM's store more energy much faster for longer periods than, say,
cold plate systems. So, where does that send the "best reefer" conversation?
I could add "water heating" & "loading engines properly at low RPM" & "long
times with no genset noise at quiet anchorages" & "cabin heat" & "ac
appliances via dedicated, correctly sized inverters" & "what else?" to the
list of design issues possibly affected by this new found ability to very
quickly store very large amounts of very versatile energy.
 
It might help, for starters, to hear from those who can say with some
certainty just how much energy a large bank of these batteries can absorb
from how big a source, and how deeply and quickly they can be drawn down.
Defining the size and quality of the power, as well as the time & energy
required to create it, could stimulate a realistic discussion of how AGM's
might affect the choice of many other components on boats. 
 
Lotsa questions and I'm too inexperienced to know many answers, but I smell
a fairly revolutionary bit of technology that has not yet been fully
exploited. 
 
Bob Frenier
Chelsea, Vermont