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Batteries should be kept fully charged as often as possible - shore power charger and/or solar depending on circumstances are the best options. If they are left below full charge for long they will sulphate and have a short life.

If your Costco batteries are true deep cycle batteries 5 years is on the low side.
 

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Batteries should be kept fully charged as often as possible - shore power charger and/or solar depending on circumstances are the best options. If they are left below full charge for long they will sulphate and have a short life.

If your Costco batteries are true deep cycle batteries 5 years is on the low side.
5 years may be a bit on the short side, seems a cheap cost for the savings of being on a mooring. Many areas that could be a savings of a few thousand a year, not to mention the peacefulness of it. I think if it were me on a mooring, I would likely set up at least some solar just to keep them topped up. even a flexible on the cabin top would likely help.
 

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5 years may be a bit on the short side, seems a cheap cost for the savings of being on a mooring. Many areas that could be a savings of a few thousand a year, not to mention the peacefulness of it. I think if it were me on a mooring, I would likely set up at least some solar just to keep them topped up. even a flexible on the cabin top would likely help.
Not suggesting a marina - if on a mooring a small investment in solar will save money on batteries over time. 40 or 50 watt panel and a small Genasun MPPT controller costs under $200.
 

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Hey,

In May of 2012 I replaced all three batteries on the boat. I paid $95.27 each for 3 Maxx 96 group 27 deep cycle. It is listed a 114AH, 845 MCA. If that lasts me 5 years I will be more than happy. I can afford $300 in batteries every 5 years. Before that, I bought 2 new batteries in 2007 (1 bat was new).

Solar would be OK but then I need to find a place to mount the panel, wire it, keep it clean, keep birds and other crap off it, make sure nothing cracks it, etc.

Since I don't use use a lot of electrical power I'll just stick the alternator.

Barry

Not suggesting a marina - if on a mooring a small investment in solar will save money on batteries over time. 40 or 50 watt panel and a small Genasun MPPT controller costs under $200.
 

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Hey,

In May of 2012 I replaced all three batteries on the boat. I paid $95.27 each for 3 Maxx 96 group 27 deep cycle. It is listed a 114AH, 845 MCA. If that lasts me 5 years I will be more than happy. I can afford $300 in batteries every 5 years. Before that, I bought 2 new batteries in 2017 (1 bat was new).

Barry
Did your boat open a wormhole and send you forward/backward in time?
 

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Welcome to the C&C Club...As Joel mentioned join the C&C group online. Lots of great information.

I would sail it for a year to figure out you needs. People waste lots of money with either mismatched electrical systems, or intiially by something with real limitations and have to upgrade and buy the correct size again later.

I know I am in the minority, but I have 6-6 volt Lifeline AGM. 720 ah or 4-5 days without needing to recharge if not able to. Refrigeration is by far our largest draw at 40-50 ah/ day. They are on their 6th year and have shown 0 drop off. For sure I do watch them and due the required maintainence on them and am able to bring them back to full charge almost all of the time. I also desulfate them regularly. They are maintainence free also.

AGM are not for everyones use, but they suit our needs, sailing profile and space requirements as they dont have to be upright.

Again sail a year and see what you needs will be, do an electrical "diet" for your boat. Dont undershoot your electrical bank amp hours either.
 

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Discussion Starter · #28 ·
AGM are not for everyones use, but they suit our needs, sailing profile and space requirements as they dont have to be upright.

Again sail a year and see what you needs will be, do an electrical "diet" for your boat. Dont undershoot your electrical bank amp hours either.
Sounds like that will be my plan. Use it, monitor the batteries and decide from there.
Why are AGMs not for everyone?
 

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Agm batteries are fussier than flooded batteries. They really require a full charge very often to get a long life out of them. The charging system should also be upgraded when switching to Agm batteries. Because they will accept very large current during bulk charging they have a habit of burning out alternators that end up running at max output for long periods of time. A good alternator with an external regulator like the Balmar MC-614 and temp sensors for both alternator and batteries is a good combination. This adds up to a lot of money and the batteries are about twice the price of flooded batteries as well. And even then many do not get the life they should expect out of them.

Good thread here regarding Agm batteries:AGM Batteries - Making The Choice - SailboatOwners.com

Flooded golf cart batteries are the best value and if treated well should last 6 years or more.
 

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Seeing how this is an electrical 101 thread I鈥檒l add to it.

I bought a 鈥渘ew to me鈥 boat in October 2013. During the two day transit from Boston to Narragansett Bay two things happened. At one point the first day I noticed the instruments and autopilot went dead. I went below and started checking things and they came back on after touching a wire. (first clue). We docked overnight and when we set out the next morning the alternator fried. At the time I thought it was some sort of back feed from the shore power that caused the alternator issue. (second clue). Fast forward to now, having the alternator repaired, $150 I asked what could have caused the failure and universally it was bad batteries. Now, having inspected the entire system the one thing that links both problems is a poor battery connection and sure enough the connections at the batteries were all dirty and corroded. Bad connection, no power to the instruments, bad connection no place for the alternator energy, fried diodes. I should have known from years of auto repairs that the first place to trouble shoot car electrical issues is at the battery connection. Lesson learned.

John
 

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John-
If you've got a common 3-wire harness on the alternator (like almost all cars do) then all someone has to do is disconnect the voltage sense lead (one of those wires) for about 30 seconds and it will fry the diodes and ruin the alternator. This is a common scam for rip-off garages to pull on customers, they disconnect the wire in front of your eyes and then hook up a meter to show you "See, it's dead" and it sure is now.
Then they'll blame it on the battery being bad, so you'll buy both a new battery and a new alternator.

But it simply is a weak point in the common alternator design. Disconnect the voltage sense lead, the alternator says "Oh the battery is so very low, I have to put out full power!" and in doing so, it can burn out in 30 seconds. And damage all the electronics and light bulbs, if they are on.

So...not necessarily a problem caused by the battery connection, although that lead goes from the alternator to a battery, same as the charging lead does.

Boats can be a hard place for electrics and unfortunately it can be a physical PITA to get close enough to make sure all the connections are clean and tight.

FWIW, If you have a "one wire" system, it doesn't have that problem, but there are always other tradeoffs.
 
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