6 volt or 12

[jbanta]

I am putting a new eletrical system aboard and have heard great things about 6 volt systems. The only problem I am having putting them in is weight. Anyone know where batteries can be had that don''t weigh 100lbs each?

[GordMay]

Your system will be 12 Volt, even though your batteries are 6V each (series wired).

Two trojan "T105" at 6V/each will have a 20 Hr rating of 225 Amp/Hours, weighing about 62 Lbs each = 125 Lbs total.

A single "8D" at 12V (same 225 A/H rating) weighs in at between 135# & 160 Lbs - and may cost as much as 50% more than the (2) 6V "T105''s".

Trust this helps,
Gord

[WHOOSH]

J, just to add to Gord''s useful comments (e.g. just imagine later changing that 8D battery out; you''d need a super strong PAIR of sons-in-law!), you can find Trojan T-105 batteries at many auto electric shops, the kind that rebuild alternators and starters. If they don''t stock them, they can order them. I recently swapped out my T-105''s for a fresh set (we''re heading out and found we had a bad cell in one battery; not good to mismatch batteries re: age) and paid $49 for each 6V 220-240 AH (I''ve seen various specs on what the Amp Hour rating of this battery is...). That was about $110 for one 12V bank, including tax & conservation fee. It''s hard to beat that kind of price for that level of quality and performance.

Jack

[sailnaway]

I just was looking at the Rolls battery they have a modular that each section only weighs around 30lbs and it takes six to make a d-8 and I think you can replace a bad cell if need be.
With the Coast Guard requiring all batteries to be contained within their own compartment or container, the 8-D is the standard size designated by the Battery Council International (20 3/4" x 11" x 10") with a general capacity of 200AH. Now, with the new 12-HHG-325, you get 325AH from the same space. The modular design incorporates removable cells weighing only 30 lbs. each, which can be installed one at a time, making installation a breeze. Featuring its own Blue Seas Coast Guard approved battery box with removable cover, this new battery replacement system fits in the same space as an ordinary 8-D contained in a battery box. An added feature of the 12-HHG-325 is its "Hydrocaps" -specifically designed recombination caps that eliminate hydrogen off-gassing and drastically reduce maintenance to once a year topping off.

If you are considering replacing your 8-d battery, take a close look at this new system offering 65% increase in capacity, improved cycle-life, low maintenance and easy installation.

For further information, call at 1-800-681-9914 or E-mail us at sales@rollsbattery.com

[WHOOSH]

J, just to try & close the loop...

You have another Trojan option, which is larger 6V units for which you can also find designated battery boxes. These used to be spelled out in WM''s catalog, or you can talk with a Trojan dealer.

After collecting the data for battery banks of comparable size, do a cost comparison: As I recall, Trojan batteries like we''re discussing offer 1200 cycles at 50% discharge rate before reacing half-capacity; ask the Rolls folks for their comparable #s. Solve for cost per cycle. I think you''ll find, whatever you think about the individual benefits of each choice, there will be a clear ''value'' winner.

BTW the problem of what to do when discovering a bad cell is the same, whether you''re dealing with 2V cells or 6V batteries composed of 3 2V cells: either way, swapping out the old component for a new one and then putting it in series/parallel with the old cells/battery remaining will result in some loss of efficiency, as the new unit will in part busy itself feeding the old units due to its higher capacity.

Jack