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Old 27-09-2009, 00:29   #31
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AGM Batteries should not be equalized if they are treated properly. If charged at the proper voltage and not discharged nore than 40% they can last more than 10 years and I have heard that 15 years is not all that uncommon. However, if they are mistreated they will sulphate like a standard battery. At this point they must be equalized. Unfortnately this will do damage to the battery, but is still better than letting it continue to sulphate.
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Old 27-09-2009, 04:51   #32
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I think I'll just try to keep 'em charged up and forget about equalisation...

I've had AGMs for 3 years now and I'm impressed with their performance.
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Old 06-10-2009, 09:31   #33
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The fact is, 'marine batteries' aren't really deep cycle batteries at all, and are just slightly better than automobile batteries for 12v electrical systems. Worst to best is as follows (using standard nomenclature):
automotive battery (i.e. Sears)
marine battery (i.e. Sears Marine)
golf cart battery (i.e. T-105)
fork lift battery (i.e. L-16)
industrial cells (i.e. IBE/Hawker)

...the last three (industrial, golf cart, & fork lift) being true 'deep cycle' batteries. And deep cycle is actually a misnomer, as your batteries should be kept above 80% charge always, and should absolutely never fall below 50% charge.
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Old 06-10-2009, 09:55   #34
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Originally Posted by Not Sure View Post
The fact is, 'marine batteries' aren't really deep cycle batteries at all, and are just slightly better than automobile batteries for 12v electrical systems. Worst to best is as follows (using standard nomenclature):
automotive battery (i.e. Sears)
marine battery (i.e. Sears Marine)
golf cart battery (i.e. T-105)
fork lift battery (i.e. L-16)
industrial cells (i.e. IBE/Hawker)

...the last three (industrial, golf cart, & fork lift) being true 'deep cycle' batteries. And deep cycle is actually a misnomer, as your batteries should be kept above 80% charge always, and should absolutely never fall below 50% charge.
Well that may have been true in the past, but the current sears marine battery is a oddssy battery TPPL in disguise.

http://www.sears.com/shc/s/p_10153_1...rine+Batteries

ODYSSEY Batteries - Battery Specifications

Now I can't say for sure how it will pan out over time, but if it turns out like I think it will, it will prove to be a better battery than the others you mention, when price, safety, capacity, time to recharge ect is taken into account.
I was a big believer in Trojan t105's in the past. After taking on water, and having those batteries leak all over the cabin, I don't think so ever again.
The future is in new battery technology, not past. Wet lead acids have their place, but I believe not on my boat.

Bob
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Old 06-10-2009, 10:39   #35
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Old 06-10-2009, 13:21   #36
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Well that may have been true in the past, but the current sears marine battery is a oddssy battery TPPL in disguise.

http://www.sears.com/shc/s/p_10153_1...rine+Batteries

ODYSSEY Batteries - Battery Specifications

Now I can't say for sure how it will pan out over time, but if it turns out like I think it will, it will prove to be a better battery than the others you mention, when price, safety, capacity, time to recharge ect is taken into account.
I was a big believer in Trojan t105's in the past. After taking on water, and having those batteries leak all over the cabin, I don't think so ever again.
The future is in new battery technology, not past. Wet lead acids have their place, but I believe not on my boat.

Bob
Boat Battery Basics: Boats and Yachts Maintenance and Troubleshooting

Boat batteries regardless of type should be contained in a covered battery box to protect them from water.
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Old 06-10-2009, 15:08   #37
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Boat batteries regardless of type should be contained in a covered battery box to protect them from water.
Note that Pascoe says "Regardless of type, it is highly recommended that batteries be mounted in rugged, covered plastic boxes specially designed for this purpose. This is to contain the inevitable sulfuric acid leaks, this acid being very damaging to all organic materials (clothing, wood) as well as most metals."

Insurance companies, who have a vested interest here, definitely feel the risk is not too high. I checked with my insurer (Zurich NA - who's actually pulling out of the marine market ) and they specifically said that securely mounting AGM batteries on their sides - without a "battery box" - was fine with them as long as they're secured in the case of a knockdown, and the terminals are covered (mine with a .25" Lexan sheet) to prevent accidental shorting.

Try to find a plastic box which can hold four L16-style batteries!

Remember that AGM's hold their electrolyte suspended in fiberglass matting, and will leak extremely little - if at all - if the plastic battery casing is breached. Salt water entering into the casing will generate chlorine, just as in FLA batteries - but at a much smaller rate.
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Old 06-10-2009, 15:42   #38
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Note that Pascoe says "Regardless of type, it is highly recommended that batteries be mounted in rugged, covered plastic boxes specially designed for this purpose. This is to contain the inevitable sulfuric acid leaks, this acid being very damaging to all organic materials (clothing, wood) as well as most metals."

Insurance companies, who have a vested interest here, definitely feel the risk is not too high. I checked with my insurer (Zurich NA - who's actually pulling out of the marine market ) and they specifically said that securely mounting AGM batteries on their sides - without a "battery box" - was fine with them as long as they're secured in the case of a knockdown, and the terminals are covered (mine with a .25" Lexan sheet) to prevent accidental shorting.

Try to find a plastic box which can hold four L16-style batteries!

Remember that AGM's hold their electrolyte suspended in fiberglass matting, and will leak extremely little - if at all - if the plastic battery casing is breached. Salt water entering into the casing will generate chlorine, just as in FLA batteries - but at a much smaller rate.
So...is your claim that the same 'flooding' that caused your other batteries to leak battery acid isn't going to affect the AGM batteries why? (which are apparently turned on their sides?) Because they have a piece of lexan _over_ the terminals?

Uh, one (or two) batteries per battery box, depending on size, with holes drilled for interconnect cables where necessary.
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Old 06-10-2009, 17:39   #39
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So...is your claim that the same 'flooding' that caused your other batteries to leak battery acid isn't going to affect the AGM batteries why? (which are apparently turned on their sides?) Because they have a piece of lexan _over_ the terminals?

Uh, one (or two) batteries per battery box, depending on size, with holes drilled for interconnect cables where necessary.
No - the lexan is to prevent any errant metal object - like a crescent or socket wrench - from accidentally shorting the battery terminals, in lieu of a plastic battery box performing the same. Obviously you haven't seen my battery bank, so don't jump to conclusions.

And I'm not just making idle claims. While I'm not a power engineer (my degrees are electrical/telecom engineering) I did lots of research when designing the new electrical system on my boat. I think our resident battery expert here on the forum, Rick (who wrote the battery "sticky" topic in this forum), would back up what I said in my earlier post.

Virtually all AGM batteries are sealed - no vents. Because they have a low internal resistance, they don't generate nearly as much heat as standard FLA batteries when charging or discharging; hydrogen gassing is greatly reduced and any pressure caused by gassing within the sealed case recombines gaseous hydrogen and oxygen back into water. So the only way they'll leak is if (a) some outside blunt force trauma breaches the case or twists the terminal head, or (b) an internal short causes thermal overloading and blasts the case from the inside - something that would probably damage any roto-molted plastic box it would be sitting in as well.

Because they're sealed, they can be mounted in any position, except for possibly upside down. Check with any reputable AGM manufacturer and they'll concur. No insurer would insure a boat with sideways batteries if there were any risks that they'd have to pay out a claim because of it. Remember - these things were designed for fighter jets for the USAF - they can handle a lot more g-forces than any shaking around a boat would do. And if they don't - hey, you've got much bigger problems than worrying about chlorine gas or acid splashing around.

You're new here - show a little respect for us old farts! Sometimes we're even right! And most of us will even admit it when we're wrong, as long as you point us to the right reference material...
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Old 07-10-2009, 01:06   #40
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Actually an AGM should have little to no leakage even if broken or punctured because the glass mats inside them are only 95% soaked with acid.

Its like taking a sponge, soaking it with water, then squeezing a (very little) bit out. You may get the occasional drip, but they will be few and far between if you even see any, and the sponge will still feel very wet obviously.

Great battery tech overall!

EDIT: Sorry I see this was mentioned 2 posts up, but I stand by my endorsement
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Old 07-10-2009, 02:56   #41
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... Try to find a plastic box which can hold four L16-style batteries! ...
The Noco (HM462) Dual L16 Commercial Battery Box 12.65"L x 15.00"w 17.75"h accepts (2) L16 Batteries at 11.625" x 7" x 16.75"
Noco Marine and Golf Cart Battery Boxes
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Old 07-10-2009, 10:20   #42
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No - the lexan is to prevent any errant metal object - like a crescent or socket wrench - from accidentally shorting the battery terminals, in lieu of a plastic battery box performing the same. Obviously you haven't seen my battery bank, so don't jump to conclusions.

And I'm not just making idle claims. While I'm not a power engineer (my degrees are electrical/telecom engineering) I did lots of research when designing the new electrical system on my boat. I think our resident battery expert here on the forum, Rick (who wrote the battery "sticky" topic in this forum), would back up what I said in my earlier post.

Virtually all AGM batteries are sealed - no vents. Because they have a low internal resistance, they don't generate nearly as much heat as standard FLA batteries when charging or discharging; hydrogen gassing is greatly reduced and any pressure caused by gassing within the sealed case recombines gaseous hydrogen and oxygen back into water. So the only way they'll leak is if (a) some outside blunt force trauma breaches the case or twists the terminal head, or (b) an internal short causes thermal overloading and blasts the case from the inside - something that would probably damage any roto-molted plastic box it would be sitting in as well.

Because they're sealed, they can be mounted in any position, except for possibly upside down. Check with any reputable AGM manufacturer and they'll concur. No insurer would insure a boat with sideways batteries if there were any risks that they'd have to pay out a claim because of it. Remember - these things were designed for fighter jets for the USAF - they can handle a lot more g-forces than any shaking around a boat would do. And if they don't - hey, you've got much bigger problems than worrying about chlorine gas or acid splashing around.

You're new here - show a little respect for us old farts! Sometimes we're even right! And most of us will even admit it when we're wrong, as long as you point us to the right reference material...
Since I qualify as an 'old fart' also, I'll dole out the respect as I deem appropriate, thanks. No offense, but in this instance, one's longevity or post count doesn't give them a 'walk' when discussing safety.

The fact is, you still haven't answered the question. Do you believe that your current setup of AGM batteries lying on their sides with a piece of lexan over them makes them any different in a flooding situation than your previous lead acid setup? (other than the potential for leaked acid). Because as far as I'm concerned, your new setup is just as toasted in a flood as your previous setup. You've just removed the majority of the potential for loose acid in your new setup ---and that is discounting entirely that when shorted by salt water your AGM's may burst regardless of whether or not they 'leak'.

If you can somehow show how you've mitigated the flood danger posed by your new battery-box-less installation, I'll stand corrected.
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Old 07-10-2009, 13:49   #43
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When you submerge an AGM battery in sea water, the only problem you get is that the battery will discharge itself into the low electrical resistance of the water. Don't think that the water will short the battery. Copper conducts electricity more than 10 million times as good as sea water (see Electrical conductivity - Wikipedia, the free encyclopedia).

I think nothing much will happen. Even if the path through the water is as low as 120 Ohms, you only get 1A discharge from a 12V system or 2A from a 24V system. If the resistance gets as low as 12 Ohms, you get 10A for 12V / 20A for 24V. All that is just not enough to create enough gas for explosive/poisonous concentrations to worry about.

I once flooded my Trojan L16's with fresh water and was highly surprised that the water did not get through the vent-holes in the caps into the batteries.

cheers,
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Old 07-10-2009, 14:06   #44
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When you submerge an AGM battery in sea water, the only problem you get is that the battery will discharge itself into the low electrical resistance of the water. Don't think that the water will short the battery. Copper conducts electricity more than 10 million times as good as sea water (see Electrical conductivity - Wikipedia, the free encyclopedia).

I think nothing much will happen. Even if the path through the water is as low as 120 Ohms, you only get 1A discharge from a 12V system or 2A from a 24V system. If the resistance gets as low as 12 Ohms, you get 10A for 12V / 20A for 24V. All that is just not enough to create enough gas for explosive/poisonous concentrations to worry about.

I once flooded my Trojan L16's with fresh water and was highly surprised that the water did not get through the vent-holes in the caps into the batteries.

cheers,
Nick.
Assuming of course that an errant screwdriver or any other piece of conductor material isn't washed nearby. No, it appears that you've just traded one problem for another, particularly since your old battery terminals, which were upright, were sticking up further out of the water than your new setup is, and therefore were better protected.

Regardless, you seemed to have convinced yourself of the 'safety' of your current setup, so what do I care.
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Old 07-10-2009, 14:46   #45
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Quote:
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When you submerge an AGM battery in sea water, the only problem you get is that the battery will discharge itself into the low electrical resistance of the water. Don't think that the water will short the battery. Copper conducts electricity more than 10 million times as good as sea water (see Electrical conductivity - Wikipedia, the free encyclopedia).

I think nothing much will happen. Even if the path through the water is as low as 120 Ohms, you only get 1A discharge from a 12V system...
However, if the path is as low as 0.04 Ohms*, you might expect get a discharge of about 3,000 Amps.

Distilled Water has a resistance of about 1,000,000 Ohms per meter; whereas Sea Water has a resistance of bout 0.1 Ohms per meter.

However, Conductivity is measured in MS/cm2 which is Micro-Siemans* per Square Centimeter. Resistivety is measured in Meg-Ohm/cm2 which is Million Ohms per Square Centimeter. These terms were adopted because Ohms of resistance per foot of distance was too easily understood.

A Siemen is a mho. It is called Siemen to make it harder to remember than mho.
Mho is Ohm spelled backwards, a clear clue to its meaning which is 1/ohms or reciprocal Ohms. Since Ohms is resistance, mhos is conduction.
Mhos had too many people understanding what was going on, so it was renamed Siemen to make it sound really technical, keeping most people from understanding it easily. A deci-Siemen is one tenth of a Siemen or 0.1 mho, and a a micro-Siemen is 1 millionth of a Siemen.

Someone help me !!!
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