Quote:
Originally Posted by asdf38
Ok
GC10 = 794 square inches = 1.62 Wh per square inch
G31 = 833 square inches = 1.511 Wh per square inch
Ok so that's a 7% advantage for the GC battery in this case in terms of energy per volume. I'll agree that's not nothing. Although I know I've run these numbers in the past, for a different pair of batteries and seen the 12V's come out ahead like it does on weight in this case. I'll try to find that.
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One thing this does not take into account is the cycle life of a 12V flooded battery vs. a 6V flooded battery when put in the same deep cycling application. The 6V batteries will outlast the 12V. I find on average 20-40% more life.
Beyond that on about 70% of the boats I work on "foot print" is the limiting factor and on about 30% height is the limiting factor.
GC2 / T105 size golf cart batteries are closer in foot print to a group 24 than a 27 or29/31 and with foot print usually being the constraint limit more so than height one must consider foot print comparisons vs. weight or box volume...
GC2 / T105 = 10 3/8" Long by 7 1/8" Wide by 10 7/8" Tall
Group 24 = 10 3/4" Long by 6 13/16" Wide by 8 11/16" Tall
Group 27 = 12 9/16" Long by 6 13/16" Wide by 8 3/4" Tall
If we compare the Deka / Duracell brand from Sam's Club (same as West Marine)
EGC2 6V = 230Ah for 2 batteries
Deep Cycle 24 12V = 150Ah for 2 batteries
The 6V batteries, in the same basic foot print of a group 24 have 80Ah more capacity for two, or nearly an entire group 24 battery... You also chose to compare weakest GC2 battery Deka makes at 215Ah/.. They also make that same case size in a 230Ah and 235Ah battery.
On boats where height is the limiting factor then 12V are often the only way to go unless you want to get spendy on Lifeline GPL-4CT's... But on boats where foot print is the limiting factor 6V batteries win hands down..
The OP really does not need much and a couple of group 24, 27 or 31's will do just fine. I would advise against the current crop of Wal*Mart batteries. Firstly they are labeled incorrectly and the labeling means NOTHING. It was clearly drawn up by a marketing department who knows squat. Secondly the new batteries are more of a dual purpose than the original Maax 29's that were actually built by US Battery and were an excellent product. I would instead look towards Wal*Marts sister store Sam's Club where in about 25 states they sell the Deka / East Penn brand of batteries.