I am a strong beleiver in the 6 volt golf cart batteries, I just installed 6 6 volt Lifeline AGM batteries and redid our electrical system with and echo charger for the starting battery for future cruising. Next year I will add some passive charging (cell or wind). I chose the Lifeline because the "footprint" was smaller than most AGM. You can lay agm on thier sides also which wasnt necessary in my case. Lifeline has a great reputation and are warenteed 100% the first year then prorated to 5 years.
We used to have 2 wet cell group 31 and a starter (AH 210) 2 of these 6 volters take up the space approx of one group 31. Had we added another group 31 we would have 315 AH. With these 6 Lifelines we have 660 AH usable 330 AH of course. Our electrical diet (per day) is about 95 AH (refrigeration taking the brunt of it). We also added insulation to the icebox and replaced the old Alder Barbour with a super cold machine) so I hope our diet reduces.
This means we can go 3 days with no charging at least.
Bought these at Tristates on line and no shipping costs. Were $245 a piece. You get what you pay for.
For? The T-105 is purely a deep-cycle batt, not great for starting a cold diesel engine. If you are talking house batteries, then maybe. Gel cells have good power densities but are too sensitive to charging rates and voltages; one mistake and you're out several hundred dollars. So they are on the way to obsolete, having been superceded by AGMs. AGMs have all the virtues of gels -- any-way-up storage, no maintenance, vibration resistance, excellent deep-cycling -- but with better charging profiles and robustness. Cost is about the same, or roughly 2x to 3x flooded batts.
AGMs will give you more cycles to 80% discharge than a flooded batt (usually), but it's wise to keep any battery in its top 50%. So really, it's down to economics and how much space you have to work with.
IMHO gel batteries have the worst characteristics of both AGM and wet-cell batteries, and really don't make much sense to purchase anymore.
A lot of what batteries you should get depends on what your usage for them are going to be, and how regularly you will do the maintenance on them. The best bang for the buck is probably 6 Volt golf cart batteries...
our boat has 2 110 A/H gel batteries that were installed in 2000. I keep them topped up with a good shore charger and I use a Balmar MaxCharge regulator and I almost never have discharged them below 50% and (knock on wood) they still seem good as new.
There have been a few reports of premature failures of AGM batteries, just as there have been reports of premature failures of gel batteries.
I suspect that, like many things, we read a lot from people who have had poor experiences but we almost never read info from happy users.
I have 7 new 8G31 MK gel batteries being charged by a Zantrex TrueCharge 40. I love that I can place them however I want in the boat and I don’t have to worry about spillage or having to top them off and burning my shirt in the process. I also love the 700 amp hours (400 useable) and the assurance that they will last for years. Downside? They cost a fortune and I had to upgrade my charger and alternator. I figured what the he11 though, I might as well spend it on the boat before I loose all of it in the market.
If anyone is looking for gells in the Northeast, PM me. I can get them at cost.
Trojan T105's are rock solid batteries, and seem to be able to stand a lot of abuse. I'm up to year 7, I was going to replace them this year, but I was out off the dock charger for four days a few weeks ago and they just kept right on going. I have a house bank of four, and two newer group 31 Trojan starting bats. However I sometimes use the T105's to start the engines, its sort of the acid test - if the engine starts, we're good.
I had 6 of the Trojan 6 volt golf cart batteries on my trimaran when we were living aboard. Wind and solar couldn't quite keep up and I was out on a mooring so I had to run them down all week and then run the generator on the weekend because I didn't like letting it keep going unattended. I ran the batteries down to about 75%-80% discharge every week for at least 2 years and they lost nothing. The next owner let them sit dead for 6 months and that killed them. For a starting battery I'd go AGM.
Billy Ruff'n was launched in November 1994. She's seen full time live aboard use for 7 of those years and seasonal use the other 8. She's has yet to consume the second set of Trojan 6V lead-acid batteries. (Start battery is a 12V Trojan combo "deep cycle starting" battery (whatever that is???)
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