bingo. you've guessed correctly - i've done no such research. matter of fact, i recently attended the new york boat show and neglected to ask any manufacturer if his boat came with a 6 volt electrical system. me culpa.
to help understand...
even though the 6v batts may be a better choice for some of us, they are not necessary for all of us...
and some that could actually benefit greatly from them, dont understand how the 6v batts could make any difference, so they wont buy what they dont understand.
and for these reasons alone it doesnt make sense for small and midsize yacht builders go to the expense of outfitting the boat with 6v batts, unless the buyer specs it out that way.
its cheaper to build the boat without the better battery arraignment, and then have an upcharge to the buyer if he/she wants them installed, rather than the builder going to the expense of removing them on his dime if the buyer doesnt want the 6v batts.
almost all large luxury yachts will be delivered with large house banks built of 6v batts.... many of them with 2 separate house banks, in addition to the starting batteries.
regular automobiles dont have any need for a deepcycle battery, but electric cars do....
and even though older electric cars, and some custom built ones still use the golf cart batts, newer and more expensive technology has entered into the newer electric cars.
as for electric driven machinery and equipment such as electric forklifts, manlifts, portable airport equipment and golfcarts, they still rely on the 6v deepcycle batteries for dependability and longevity under sometimes extreme conditions....
the battery could be any voltage depending on the number of cells, but due to convenience of handling the extra weight of the deep cycle battery, 3 cells is the best size for standardization.
when there is equipment available to handle even larger and heavier individual batteries, taller cells are common, which equate to larger plates (more stored energy), and more cells can be added to get any voltage that is required (in multiples of 2volts).
these very large batteries are used in special applications were the battery must deliver an extremely large amount of power for an unusually long time, and has a very high powered charger to replenish it immediately after use, and the battery is installed for its lifetime and will never be, and never was intended to be handled by a human.
I have a single battery in my shop right now that measures 48" wide, 24" thick, and 30" tall.. out of an electric forklift. its a 48volt deep cycle battery. I dont now what the Ah rating is, but i can only guess if it was rewired for 12volts, it could run the electrical needs on an average 34ft sailboat for nearly 6months before the lights went out.... some boats could probably get a year out of it.
