www.iFourWinns.com

Is anyone using AGM (Absorbed Glass Mat) batteries in their boat?

My dad just replaced the batteries on his sail boat this week. The 3 house batteries are Lifeline GPL-8DL and the starting battery is a Lifeline group 31 GPL-31T.

My batteries are three years old and one of them starting to give me problems. On the heels of his purchase I can get a 40% discount on two group 27 Lifeline GPL-27T batteries. Still i'm not saving any money and probably spending $100.00 more for the set.

Is there any reason to spend the extra money on AGM batteries instead of standard acid flooded type?

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Jeff
2006 H240 6.2 MX 320HP B3
La Habra, California

At the beginning of last season, all of my lead-acid batteries were replaced with AGM's (I carry four). I have been thoroughly pleased with their performance and enjoyed the absence of maintenance (no water to check and top off).

Here's some basic info that may inform your decision and answer your questions...

-Gel and Absorbed Glass Mat (AGM) batteries can dispense charge at a higher rate than flooded cells. Deep-cycle Flooded Cells cannot deliver more than 25% of their rated amp-hour capacity in amps without plummeting Available Capacity.
-Deep-Cycle Flooded cell battery manufacturers recommend a 4 to 1 ratio between battery bank size and the largest load encountered on board.
AGM and Gel cell manufacturers recommend a ratio of at least 3 to 1, a significant difference for loads such as the engine starter or windlass.
-Virtually no gassing under normal operating conditions: Unlike flooded cells, gel cells and AGMs are hermetically sealed and operate under pressure to recombine the oxygen and hydrogen produced during the charge process back into water.
-Gel cells and AGMs require no maintenance once the charging system has been properly set up. No equalization charges (usually), no electrolyte to replenish, no specific gravity checks, no additional safety gear to carry on board in order to protect yourself.
-The higher charge efficiency of AGMs allows you to recharge with less energy: Flooded cells convert 15-20% of the electrical energy into heat instead of potential power. Gel-cells lose 10-16% but AGMs as little as 4%.
-While flooded cells lose up to 1% per day due to self-discharge, AGM's lose 1-3% per month.
-High vibration resistance: The construction of AGMs allows them to be used in environments where other batteries would literally fall to pieces. This is another reason why AGMs see broad use in the aviation and the RV industry.

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Previously:
2008 V358/Volvo 5.7 GXi Inboards

And if you have deep pockets, and want the ultimate in batteries, choose Lithium Ion.

Torqeedo Power 26-104 is uncompromisingly designed for marine use. It is waterproof to IP 67 standards, so it can be completely submersed at 3' for 30 minutes and still function properly. It will also shut itself down if submersed longer to avoid dangerous galvanic effects. Superior safety aspects of the new battery encompass proven and secure battery chemistry, advanced safety electronics, as well as unique hardware protection of each individual battery-cell. Delivering 2,685 watt-hours from a weight of only 44 lbs., the new Power 26-104 features four times the energy per pound of battery weight compared to conventional lead-gel or AGM batteries. It outperforms other lithium batteries on the market.

Advantages of Lithium Ion Batteries

*Fast Charge Ability
*Light weight
*High Energy Density
*Safe & Green
*Zero Maintenance
*Easy to Install
*Temperature Tolerant
*Low self dissipation

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One of 4 Previous (Sold) Boats:
2000 Four Winns 268 Vista

Current Boat: 2004 Chaparral 235 ssi cuddy

"Is there any reason to spend the extra money on AGM batteries instead of standard acid flooded type?" - One consideration I would have is how accessible are your existing battery(s). If they are a real bitch to get at to check the water levels than I would be looking at AGM's.

On my 328, I just replaced a house battery last weekend and I had a brand new flooded cell group 27 battery in my basement that I had purchased for my previous boat but didn't install because we sold it.

If I didn't already have this new battery I would of bought an AGM ( or similar non flooded type) as where the house battery is in the 328 it is not real easy to check the battery water levels. The two starting batteries on my 328 are maintenance free ones - Glad they are.

Mike.

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Current Boat
- 2001 Four Winns 328 Vista "Hour Decision"
- 2010 310 Mercury Inflatable

Previous Boats
- 30' Doral Prestancia
- 25' Doral Citation

Last month I replaced both standard acid flooded batteries with the AGM group 27 Lifelines. The AGM batteries are much heavier than the acid flooded type. Between both batteries I'm guessing I added an additional 20# to the port side of the boat. Supposedly the AGM batteries will only lose 1%-3% total charge per month. My plan is to not pull or disconnect the batteries over the winter. I'm headed up to run the boat this weekend for the last time this season and won't see her until next May (roughly 6 months). I'll report back either way.

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Jeff
2006 H240 6.2 MX 320HP B3
La Habra, California

Last winter, my first with AGM's, was my first not storing batteries off the boat on a trickle charger. I left them on board, disconnected, with my mechanic's blessing. I saw no noticeable difference in battery performance this season. Just do your best to disconnect them with as full a charge as possible.

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Previously:
2008 V358/Volvo 5.7 GXi Inboards

When changing to AGM batteries do you not have to make any changes to the shore charger or alternator?

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Oliver
'06 V278
Singapore

I run group 29 deep cycles from Walmart.

They have been nothing short of spectacular for 85 dollars each (after tax).

They'll run 2 fridges, radio, and the wife's crazy needs for a weekend without a hiccup.

And for the price... if they go bad in 3 years, I'll replace them knowing I got my use out of them....

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2008 318 Vista -SOLD, but I am still around!
All Night Long, Seattle WA

I never expected to use luxuary and Walmart in the same sentence but here goes: "Unfortuntely in Singapore we do not have the luxuary of picking up cheap batteries at Walmart"...
I'm hoping a good top up of water will sort out the issue in the near term.

Thanks for all the responses guy - Merry Xmas!

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Oliver
'06 V278
Singapore