While looking to see what 500 AH of deep-cycle battery would weigh (I
*should* know, I used to carry 400 AH on Scamp) -- 250-350# or more
-- I stumbled on an absolutely fantastic battery resource page that
arose because of an argument between an engineer whose day job is to
build cost models and a former president of Chris-Craft who wrote an
article about economical use of batteries that he apparently pulled
from where the sun don't shine.

He shoulda stood in bed, but we're the beneficiaries -- including a
simple spreadsheet model (bulk-charging only considered) for
costing-out battery choices, a wire-sizing spreadsheet (to ABYC --
American Boat and Yacht Council, I think; at any rate a standards
organization) that probably will advise larger wires than automotive
sources would, but could undoubtedly be tweaked if desired; and on
application to the author a much fancier model that includes
absorption and float stages of charging.

  --
David Beierl - Providence RI USA -- http://pws.prserv.net/synergy/Vanagon/
'89 Po' White Star "Scamp"