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hathanger 02-26-2005 07:13 AM

Golf cart batteries
I''m a first time sailboat owner, have an Ericson 35. I need to replace the batteries and have heard that many boaters use golf cart batteries instead of marine ones. What do you use and why? Would appreciate any input. Thanks

boatbum 02-26-2005 10:07 AM

Golf cart batteries
You will need two 6v Golf Cart Batteries, T-105''s or T-135''s. You wire them in series, plus to minus. You then have 12 volts. The reason to use them is that they are one of the few, and have no equal in price, that will take 1000 deep discharges and still function. "Marine Deep Cycle Batteries" are generally useless junk for a cruising boat. If you buy 4 of the golf carts, you will have a serious house bank. Sam''s Club has a good price on them, stay away from boatus/west/ripusoff stores, you''ll pay double for the batteries. The down side now is that anemic 35 amp alternator you most likely have will take forever and a month plus two days to bring back your house bank. You’ll need to upgrade the alternator to about 100Amp (max with a single pulley)and get a smart regulator. Two stage ok, three stage better. It’s a fun project and it will be worth it. Just don’t waste your money and effort on “Marine” batteries, they are for powerboat bozos.

JeffC_ 02-26-2005 07:09 PM

Golf cart batteries
Boatbum, can you please explain the phrase <em>they are one of the few</em>? I''ve read it several times now, and I can''t figure out what you mean.

I"m sure I''ve read a Don Casey article on this site in which he recommends an alternator that has an output roughly equal to 25% of your house bank capacity, i. e., a 25 amp alternator is sized right to charge 100 amps of battery capacity. I seem to remember him suggesting that this 25% charge rate helps extend battery life. Someone tell me if I''m mistaken here. At any rate, the article, or another one very much like it, could be found with a simple search.

JeffC_ 02-26-2005 07:12 PM

Golf cart batteries
Just found the article: it''s by Tom Wood, entitled "Standard Onboard Charging Systems," behind the features tab in the Electrical Systems archive.

Nereus32 02-27-2005 05:06 AM

Golf cart batteries
yes, JeffC_, you are correct with the 25% rule as it applies to wet type lead acid batteries. However, a smart charging regulator tends to make the rule obsolete as it regulates the current to the batteries. 25% rule is more for unregulated (or pooly regulated) charging plan. It would be a waist, though, to install an alternator with the capacity of 50%, as the regulator wil not let it run to it''s capacity. It''s all a matter of find a good balance between batteries/regulation/charging.

windship 02-27-2005 05:14 AM

Golf cart batteries
Mabey a wind turbine??


p32 02-27-2005 08:34 AM

Golf cart batteries
I have 6 Trojan T-105''s in my boat. I have them configured in series-parallel as described by boatbum above, then in banks of 4 and 2. I use the 2 battery bank as the starting battery and the 4 battery bank as the house battery. The bank of 4 gives 440 amp hours of capacity, so if you go this route, a 100 amp alternator is about right. I have a Balmar 100 amp with their 3-stage regulator. Seems to work pretty well with my battery configuration.
I would recommend these batteries as good value for the money. I paid about $75 each about 5 years ago. I have had to replace the batteries about every 8-9 years with usage mainly on weekend cruises with a fridge being my biggest draw. I have tried "marine" starting batteries and gotten 2-4 year service so in my experience the golf cart batteries have been a good investment.

I''ll definitely use the T-105''s again (hopefully not for several more years) although I will probably reconfigure to the more recent recommended way of doing things and do away with the 1-2-Both switch in favor of a totally automatic system like discussed here:

There''s lots of info available on this subject on the web, just do some Google searches.

A disadvantage of the 6V batteries is extra connections to wire them in series-parallel.


dougyoung 03-13-2005 11:36 AM

Golf cart batteries
Close to the same setup I have. I use an "Optimist" Starting battery, It came with the boat. I''m curious, do t T-105''s have the cranking amps you need to start your motor? I was always under the impression that T-105''s were fantastic for the house bank but not so good for starting.

When my T-105''s kick off, I plan to replace them with the new 6v AGM''s that have come on the market.

boatbum 03-13-2005 03:23 PM

Golf cart batteries
They''ll start a high compression turbo diesel, not to worry.

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