Battery Selection Question - Page 2

**Pblais** · 01-10-2008, 18:53

OK, it could be worse. It sounds like the basics are all behind you. Things that add to the mix include a Battery Monitor. They can measure the amps used and the current amp load. With information like that you have a real battery fuel gage. Think about adding something like that to the system. It lets you see what the load is and what the amp recharge is (when charging). If you know the in's and the out's you can read the integral in your head. Calculus never got so easy when you have real life in the cross hairs.

Now the batteries are like the fuel in the tank! Way cool stuff these battery monitors.

Strygaldwir · 01-10-2008, 19:45

I keep on reviewing charging lifes of AGM vs FLA. It seems like on the whole FLA's support a higher number of charging cycles in comparison to AGM's.

Whimsical · 02-10-2008, 05:34

Quote:

Originally Posted by Wotname

Both will fail early if left dischaged (or partially discharged) for any length of time

Goeff
From what I have read the AGM is far more sensitive to being left in a slightly discharged state than the FLA is.
Do you still have contacts for NiCads that have been swapped out,usually at about half life, why not use them.

Mike

**Pblais** · 02-10-2008, 05:52

Quote:

I keep on reviewing charging lifes of AGM vs FLA. It seems like on the whole FLA's support a higher number of charging cycles in comparison to AGM's.

The otherside is it takes more input to recharge a flood battery due to higher internal resitence. The accptance rate is higher and they wate less of the input energy. AGM's are cheaper to to own if you have to pay to recharge them like from your alternator for example.

Caribsailors · 06-10-2008, 20:08

Thanks Wotname... I'm in the midst of redoing my battery, charger, monitor systems.

I have installed a Xantrex XC 3 bank charger with temp sensor on house bank.
I have FINALLY installed a Link20 battery monitor, I tried to get the CruzPro.

Anyway now for the batteries..... from my research and reading, I have decided to go with four 6volt AGM's in a series parallel configuration for the house because of the AH of the 6's compared to 2- 4D's along with weight and space.

For the start battery is where I'm waffling, I haven't decide on another two 6's or one 12v. AGM also

Thanks for everyones input... great reading it has put the gears in the noggin turning

Cheers

Pelagic · 06-10-2008, 20:19

Quote:

Originally Posted by Whimsical

From what I have read the AGM is far more sensitive to being left in a slightly discharged state than the FLA is.
Mike

Where did you read that Mike, cause I have read the opposite that "stratification" is not an issue for AGM's

Nick

**btrayfors** · 06-10-2008, 21:09

Coupla data points:

1. AGMs are currently about three times the price of FLAs; and
2. AGM longevity (in "life cycles") is highly dependent on average depth-of-discharge (DoD).

If you contemplate using batteries in an application where they will be routinely discharged to more than about 50-60%, you're likely better off with FLAs as they will produce a greater number of useful cycles. And, of course, they're 1/3 the price to begin with.

Typical AGM specifications for a 40% DoD, however, are about 1,500 cycles. Pretty good!

However, if it's both cycles and ability to be deeply discharged you're looking for, it's hard to beat the Rolls/Surette batteries. These FLA designs -- which are costly -- typically last over 10 years, way past the likely longevity of AGMs.

It's true that both AGM and FLA batteries deteriorate if left for long at less than a full charge (due mostly to sulfation, not stratification). However, AGMs have a much lower self-discharge rate, so you might be better off with them if you contemplate leaving the batteries unattended and not on a charger for substantial periods of time.

Newer, better technologies are in the wings (and are even now available on a limited basis to military and some industrial users). We can only hope that they'll be available on the general market in a year or two.

Meanwhile, FLAs are definitely the price-point technology. But, AGMs have a great deal of appeal for some situations, too.

Bill

Whimsical · 07-10-2008, 01:17

Quote:

Originally Posted by Pelagic

Where did you read that Mike, cause I have read the opposite that "stratification" is not an issue for AGM's

Nick

Theres been some posts, here I think, where agm's have died a premature death and the feedback from the manufacturers was that they must be bought back to a full state of charge. Operating them between 50 and 90% kills them quick.

Mike

donradcliffe · 07-10-2008, 07:13

The nice thing about gel batteries is that you can operate them partially discharged without losing capacity. For your boat, I'd recommend a 75 ah gel starting battery and a 200 ah house battery. Cost is about the same as the AGM's.

01-10-2008, 18:53	#16
Pblais Moderator Site Helper Join Date: Mar 2003 Location: Hayes, VA Boat: Gozzard 36 - Bright Eyes Posts: 4,514 Images: 7	OK, it could be worse. It sounds like the basics are all behind you. Things that add to the mix include a Battery Monitor. They can measure the amps used and the current amp load. With information like that you have a real battery fuel gage. Think about adding something like that to the system. It lets you see what the load is and what the amp recharge is (when charging). If you know the in's and the out's you can read the integral in your head. Calculus never got so easy when you have real life in the cross hairs. Now the batteries are like the fuel in the tank! Way cool stuff these battery monitors. __________________ Paul Blais s/v Bright Eyes Gozzard 36 37 15.7 N 76 28.9 W

06-10-2008, 20:08	#20
Caribsailors Registered User Join Date: Jun 2008 Location: Somewhere in the Caribbean Boat: Beneteau First 38 Posts: 37	Perfect Thread Thanks Wotname... I'm in the midst of redoing my battery, charger, monitor systems. I have installed a Xantrex XC 3 bank charger with temp sensor on house bank. I have FINALLY installed a Link20 battery monitor, I tried to get the CruzPro. Anyway now for the batteries..... from my research and reading, I have decided to go with four 6volt AGM's in a series parallel configuration for the house because of the AH of the 6's compared to 2- 4D's along with weight and space. For the start battery is where I'm waffling, I haven't decide on another two 6's or one 12v. AGM also Thanks for everyones input... great reading it has put the gears in the noggin turning Cheers __________________ As I sit, a swirling sea of passion gives it's poems in waves underneath me. The whispers of the sun in my eyes, a silence within. Rhythm of the surf, drums of the sea. Thoughts tumble and toss about the deep blue abyss inside me, where the love of you dwells. I'm fighting currents to get back to you, listening to the flow of your liquid language as you beckon me, "Come Play" Mariners Cove, CI. Anonymous.

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01-10-2008, 19:45	#17
Strygaldwir Registered User Join Date: Dec 2004 Location: Herndon, Virginia Boat: Privilege 37 Posts: 575 Images: 5	I keep on reviewing charging lifes of AGM vs FLA. It seems like on the whole FLA's support a higher number of charging cycles in comparison to AGM's.

06-10-2008, 21:09	#22
btrayfors Moderator Site Helper Join Date: Jul 2006 Location: Chesapeake Region Boat: 42' Perry sloop, "Born Free" Posts: 854	Coupla data points: 1. AGMs are currently about three times the price of FLAs; and 2. AGM longevity (in "life cycles") is highly dependent on average depth-of-discharge (DoD). If you contemplate using batteries in an application where they will be routinely discharged to more than about 50-60%, you're likely better off with FLAs as they will produce a greater number of useful cycles. And, of course, they're 1/3 the price to begin with. Typical AGM specifications for a 40% DoD, however, are about 1,500 cycles. Pretty good! However, if it's both cycles and ability to be deeply discharged you're looking for, it's hard to beat the Rolls/Surette batteries. These FLA designs -- which are costly -- typically last over 10 years, way past the likely longevity of AGMs. It's true that both AGM and FLA batteries deteriorate if left for long at less than a full charge (due mostly to sulfation, not stratification). However, AGMs have a much lower self-discharge rate, so you might be better off with them if you contemplate leaving the batteries unattended and not on a charger for substantial periods of time. Newer, better technologies are in the wings (and are even now available on a limited basis to military and some industrial users). We can only hope that they'll be available on the general market in a year or two. Meanwhile, FLAs are definitely the price-point technology. But, AGMs have a great deal of appeal for some situations, too. Bill

07-10-2008, 07:13	#24
donradcliffe Registered User Join Date: Mar 2007 Location: Heading south for the winter Boat: Beneteau First 456 Posts: 304	The nice thing about gel batteries is that you can operate them partially discharged without losing capacity. For your boat, I'd recommend a 75 ah gel starting battery and a 200 ah house battery. Cost is about the same as the AGM's.