AGM Batteries vs Wet Cell

[monkeyfeet]

Hi

Just wanting some opinions with regards to AGM vs. wet cell's. Specifically for a sail boat that will be cruising not just a live aboard on the dock. We will be cruising continually for 3 years. Any opionions on which is better would be appreciated. Our boat is equipped with regulator and a divertor.

Thanks

[Therapy]

http://www.cruisersforum.com/forums/...ery-11113.html

http://www.cruisersforum.com/forums/...ies-11268.html

http://www.cruisersforum.com/forums/f14/agm-7356.html

http://www.cruisersforum.com/forums/...otes-5566.html

[bruadair]

When we left to go cruising three and a half years ago we purchased Lifeline AGM batteries, the dealer said these were the best batteries around. After one year performance decreased greatly and after contacting Lifeline they said to equalize them for six hours at 15.5 volts, but no more than once a year. After equalizing them they performed better, but only after six months. So I contacted Lifeline again and they suggested equalizing the batteries again and to do so every six months.

After three years the batteries no longer performed. I was highly disappointed that my 'maintenance free' batteries didn't last up as I was told they would. It is important to say that they were never discharged less than 50%, usually no less than 25%, charged regularly with solar and wind. Followed all of Lifeline's instructions.

Lifeline now states on their web site that their AGM batteries must be recharged to 100% every time that they are charged for maximum battery life. Failure to charge to 100% every time will result premature battery failure.

They go on to state that AGM batteries may not be the ideal battery choice in an application where the batteries can not be charged to 100% every time a charge is applied.

As a cruising boat it is impossible to charge batteries to 100% every time a charge is applied. Solar panels and wind generators apply a charge but this isn't enough to charge to 100% every single time. Lifeline tells me that this is why my batteries failed prematurely. Of course none of this was published when I purchased my batteries. Lifeline says that in applications where the batteries are in a charged state most of the time then charged to 100% when they are discharged these batteries will perform as advertised. Boats primarily at a dock will do great with these batteries. Cruising boats away from the dock most of the time will not like these batteries. We have met many cruisers who have left their AGMs behind and taken on Trojans like we have.

For more information about AGM batteries you might want to read their web site. On their web site you will find their instructions for equalizing their batteries.

All just my opinion and/or my experience,

[AnchorageGuy]

as a marine service tech for more years than I care to count, I have found the same issues that Bruadair encountered many times. For the cost of these batteries it just does not seem worth it on a cruising boat. You can replace the wet cell batteries for less money and get more years use for the same dollars with replacements. Plus eliminate some extra weight.

[CSY Man]

Ditto.

Good old Lead Acid wet cells will last 5 years or more if taken care off.

I have good experience with DEKA.

Marine Batteries and Boat Batteries - Gel Batteries, Gel Cell Batteries and Dominator - AGM and AGM Batteries

[senormechanico]

Brudair,

The problem with your AGM Lifeline batteries is that you actually USED THEM!
<sarc>

Steve B.

[Joli]

We use wet cell golf cart batteries and have had good luck with them. Sams Club is selling 6 volt deep cycle golf cart batteries for $66. Pretty sure they are East Penn GC 10's 190 AH. They seem to last about 5 years or so.

[slomotion]

Don’t know about Lifeline. Our AGMs were made by Concord (I think). We never had a problem in 3 years - in fact, I don’t think I ever saw them again after installation. We had professional installation and a smart charger programmed by a guy who evidently knew what he was doing. I don’t think they were ever 100% charged - usually somewhere between 60s and 90s depending on demand. The whole set up cost $2000+. But this was 8 years ago, so maybe the price difference has changed.

Our sole reason for going this route was to get an 800 amp/hr battery bank into a 34 foot boat. There was no way to accomplish this without mounting batteries in odd locations which would have been impossible or dangerous with wet cells - we also got rid of the boat’s built-in starboard list. If you don’t mind the maintenance and you have easy access, wet cells are bound to be more cost effective.

[jdoe71]

Slomotion, pretty sure that Lifeline batteries are a Concorde brand name. They are on the same website anyway.

Concorde Battery - AGM Aircraft Batteries

[slomotion]

Hmmm - maybe we had aircraft batteries. All I can tell you is that I knew I was clueless so I relied on a professional to select them and they worked for us.

Maybe they have quality control issues. Or, maybe the charger makes a difference - we were told this was critical. Or, maybe you would get better results if you just put tape over the Lifeline name and wrote 'Concorde' on it - hope this helps

[hellosailor]

CSY-
"Good old Lead Acid wet cells will last 5 years or more"
You realize the folks at Rolls and Surette would tell you 10-15 years is a more reasonable expectation.<G>

Monkeyfeet, in wet cells you have the choice of "deep cycle" "marine" "traction" "industrial" "commercial" and other quality grades. The difference is a physical difference in the plate construction, with typical deep cycle batteries having about a 5-year useful life, and the bigger, heavier, way more expensive industrial/commercial batteries hitting 10-15 plus years. But, they will be bigger, heavier, and more expensive per amp-hour of capacity.

With AGM batteries you usually can find traction (designed for fork lifts and wheelchairs and golf carts) grade or standard deep cycle, again targeted to the 5-6 year market.

Most folks have found the performance--aside from the variation in brands--to be about the same, if they are charged properly. The AGM advantage is that there is no liquid acid to spill. The tradeoff is that they are more expensive, and if you boil out electrolyte you can't simply top them up, it is gone forever. On the other hand, they also have a higher charge acceptance rate, so all things being equal you can motor 25% less and still get a full charge into the battery without boiling it.

Look around at the old threads on sailing forums and some of the battery sites on the web--there are a lot of opinions but they all agree on most of the larger points. Most unusual to hear a LifeLine owner complain about poor battery life.

[FrankZ]

Originally Posted by slomotion

...Or, maybe you would get better results if you just put tape over the Lifeline name and wrote 'Concorde' on it - hope this helps

Do you really think this type of reverse engineering should be done in the field?

[camaraderie]

Ditto that HS...if you charge them right, AGM's perform beautifully over time. They are also less expensive over time than standard wet cells due to their # of life cycles and so are ideal for a full time liveaboard who wants to charge a big bang QUICKLY (you can put in any amount of amps you want during bulk charging rather than limiting to 15-20% as with wet cells). We had a 130amp charger and a 110amp alternator and the TIME spent charging is a big deal. I found NO need to charge to 100% every time, but I DO think it is important to only discharge to around 50% and to put on a 100% charge every couple of weeks to prevent sulphation.
I believe that most of the reported problems with ANY type of battery are due to some combination of poor charging/discharging practices or poor maintenance and that most could get a lot more out of their batteries than they do.

For those with interest in the relative economics of various batteries...this is a great link:Cost comparison of AGM, Gel, and flooded batteries
The rest of the site is quite interesting as well.

[MidLandOne]

Personally, even with replacement of our service batteries a year or so back, have stuck with known brand wet lead acid (in our case we have always used Trojan). The supplier who dealt in a variety of makes and types of batteries including for fishing and other commercial fleets asked what makes I had considered and if had considered AGM (for ISAF Offshore Special Regulations for race sail boats sealed batteries are recommended from a safety point of view). I stated "Yes, but prefer wet" to which he said he thought that was the best option too for non race boats undertaking independant cruising.

I managed the build of some commercial power boats for a client a while back who used AGM's. BUT he replaced all batteries annually to ensure reliability.

[Alan Wheeler]

They are also less expensive over time than standard wet cells due to their # of life cycles and so are ideal for a full time liveaboard who wants to charge a big bang QUICKLY (you can put in any amount of amps you want during bulk charging rather than limiting to 15-20% as with wet cells).

No that is not entirely right. Firstly, AGM's will never last as long as an equivilant FLA. However, it is all in measuring the equivilant and how you compare the apples and oranges, to work out the difference. To say this another way, even FLA batteries have large differences in longevity in regards to design types. My FLA's have a 10yr warranty.
The other comment on charging is also not entirely correct. Once again it's all in how you compare the apples and oranges. If monitored, you can certainly charge an FLA battery with significantly more charge than the 20% figure and the opposite can be true with AGM, if not monitored correctly. So looking at this Genericaly, it depends on other factors aside from design type.