AGM vs Gel Batteries

[stevensuf]

nb i like the point he makes about if you are using an engine or genset to charge your batteries , saving 10-15% on run time / fuel/maintenance

[motion30]

Originally Posted by stevensuf

here is a very good study of batteries for marine use , he even works out cost vs life per watt a bit anal, but there you go!
Battery Types: Flooded versus AGM and Gel

I would like to find the life lines at the cost quoted The ones I purchased were over $500 and I looked around awhile

[norsearayder]

not long ago i head of acid battery leaking on a nother cruiser here,they breathed in the fumes for a week before they found the problem and replaced the bats. in a small vessel you are never far away from this possibly explosive fumes or poisonus fummes, i run agms on both start and house,no problem mon,4 years running

[sy_gilana]

We regularly get 6+ years out of our Trojan T105's, and the TCO (total cost of ownership) is the lowest. Friends with expensive batts, were still paying the mortgage on their batteries, when we bought our second set, and now were on our third, (just purchased) With Automatic watering system theyre hard to beat.

[hellosailor]

Talisker-
This man's way of looking at it?
1-Wet cells, cheap, can be abused because you can top up the electrolyte.
But that damned acid always gets to eat something, and in 30 days without charging they will damage themselves from self-discharge. AGM and gel don't have that problem, they can sit for a couple of months and be happy.

2-Gel cells. According to the makers, the champs at getting the most and deepest cycles for the buck without damage. Sealed, no acid burns. Big drawback? Easily overcharged and permanently damaged--which is no problem IF your charging system is matched and operated properly. Costs more than wet cells up front, costs way less per charge cycle if you care for them properly. Which mainly means, everything has to match the voltage they want.

3-AGMs. Not as good as gels, but they take "wet" charging system voltages. No acid burns. Costs a bit less than gel up front, costs about 30-50% more than wet. Won't give you as many charge cycles as gel but generally is comparable to wet--except the real deep cycle wet, like fork lift batteries and those two pricey brand names. A good compromise for a lot of people, especially if there will be some "month or three sitting alone" when wet lead would take damage. Overcharging will kill AGMs, but I've had one go eight years before it died. Well, didn't exactly die, it just said "Go away, I'm napping." I thought it didn't last very long--till the battery guy read the code and told me how old it was.

If I was going all-new and for the long term? I'd go for gel. And make Real Damn Sure the system was set up to not overcharge them. If I had to go cheap? I'd go wet lead and buy extra clothes and baking powder for the spills.

[stevensuf]

the two agms in my boat that i just replaced were originals from 2001, the boat was ex charter so you can imagine the abuse it took, they were still holding 80ah down from 180ah originally.

[Kettlewell]

1. Deep-cycle wet cells: cheapest to purchase, decent longevity (5 years give or take), require maintenance of water level.

2. Gel cells: according to manufacturers are the most durable in deep-cycle applications, but generally do not have as much capacity for the same size, cost at least double the wet cells, and require slightly lower voltage charging regimen.

3. AGMs: according to manufacturers are not as long lasting in deep-cycle applications as 1 or 2, but do have a very high charge acceptance rate and can achieve decent longevity if you charge them carefully and often to maximum. They do not accept charging abuse as well as 1, and even under the best of conditions will not last as long as 2, but cost as much as 2. Read the eleven steps to better battery life if you want to see what is required.

My vote would be for wet cells as the best cost/benefit ratio, unless having non-spill, non-watering, non-gassing batteries is important to you and worth the extra cost.

[Viking Sailor]

Originally Posted by hellosailor

Talisker-
This man's way of looking at it?
1-Wet cells, cheap, can be abused because you can top up the electrolyte.
But that damned acid always gets to eat something, and in 30 days without charging they will damage themselves from self-discharge. AGM and gel don't have that problem, they can sit for a couple of months and be happy.

2-Gel cells. According to the makers, the champs at getting the most and deepest cycles for the buck without damage. Sealed, no acid burns. Big drawback? Easily overcharged and permanently damaged--which is no problem IF your charging system is matched and operated properly. Costs more than wet cells up front, costs way less per charge cycle if you care for them properly. Which mainly means, everything has to match the voltage they want.

3-AGMs. Not as good as gels, but they take "wet" charging system voltages. No acid burns. Costs a bit less than gel up front, costs about 30-50% more than wet. Won't give you as many charge cycles as gel but generally is comparable to wet--except the real deep cycle wet, like fork lift batteries and those two pricey brand names. A good compromise for a lot of people, especially if there will be some "month or three sitting alone" when wet lead would take damage. Overcharging will kill AGMs, but I've had one go eight years before it died. Well, didn't exactly die, it just said "Go away, I'm napping." I thought it didn't last very long--till the battery guy read the code and told me how old it was.

If I was going all-new and for the long term? I'd go for gel. And make Real Damn Sure the system was set up to not overcharge them. If I had to go cheap? I'd go wet lead and buy extra clothes and baking powder for the spills.

+1

I have had all three types aboard. Currently, have two 8D AGM's, two group 27 AGM's, and a group 31 GEL. The GEL has been the easiest to maintain over the years. When the big AGM's finally die I'll replace each 8D with three group 24 GEL's. The three group 24 GEL's fit into the 8D box and have same Ah rating as an 8D GEL. The group 24's will be a lot lighter and thus easier to get in and out of the bilge and boat.

Yes, spending $1200 on six new GEL's every five years while cruising is a big deal. But that is only $240 a year from the cruising kitty. And, that is most likely worst case.

[four winds]

Two group 31 AGMs have lasted 5-6 years in my boat, owned for almost two years now. 50amp alt, recently changed to 80amp and shore power for charging. In a marina most of the last two years except three months on the hook last summer, not sure about the past years but believe marina stays mostly.

One battery shorted a cell recently so I'm looking at the need for 220 Ah of new batteries. Replacement AGMs are $650. Flooded golf cart batteries about $300.

Wish I could afford AGMs but can't even get the wet batteries just yet so I'll limp around on one old AGM for now.

The thing is, wouldn't good golf cart batteries last 5-6 years as well? I'm on the boat full time and know how to take care of them.

If money wasn't an issue I'd go AGM again for convenience but can't justify twice the price on my budget for the same service life.

[Viking Sailor]

Originally Posted by four winds

Two group 31 AGMs have lasted 5-6 years in my boat, owned for almost two years now. 50amp alt, recently changed to 80amp and shore power for charging. In a marina most of the last two years except three months on the hook last summer, not sure about the past years but believe marina stays mostly.

One battery shorted a cell recently so I'm looking at the need for 220 Ah of new batteries. Replacement AGMs are $650. Flooded golf cart batteries about $300.

Wish I could afford AGMs but can't even get the wet batteries just yet so I'll limp around on one old AGM for now.

The thing is, wouldn't good golf cart batteries last 5-6 years as well? I'm on the boat full time and know how to take care of them.

If money wasn't an issue I'd go AGM again for convenience but can't justify twice the price on my budget for the same service life.

As a temporary solution you could get a very inexpensive set of batteries, such as these from Wallmart:

Walmart.com: EverStart 24DP-4 Marine Battery: Automotive

They run around $70 each here on the left coast. These are rated for 105 Ah and should last long enough to allow you to up grade to a good set of AGM's or GEL's in a year or so.

[four winds]

Thanks for that info Viking.

I didn't realize that type of Wal Mart battery was 105 Ah. That would be about $150 for the same capacity as my current pair of $650 worth of AGM from SeaVolt, 105 Ah each.

I'm amazed and confused. Most every battery I've owned in cars and bikes has lasted 5 years usually and dies during a change of seasons in the winter or summer.

I'm rebedding ports and doing some inexpensive maintenance right now so not going anywhere far until I sell a car I don't need anymore. But I should consider your advice, so I won't have to worry about the other AGM failing while doing an overnighter in Perdido Bay or over in Pensacola anchoring out to watch the Blue Angels practice.

Thanks

[Adelie]

Originally Posted by downunder

Talisker indicated he has a winter layover period which means AGM's would be better over flooded cells.

He also indicated he had 10amp shore service.

Check this link out: Systems.

Evans is a CF Adviser if I recall correctly. In any case he is a regular contributing member.

[Kettlewell]

Best battery deals right not are at Sams Club where you can get Deka-Penn deep cycle batteries that are identical to the ones sold by West for twice the price, as confirmed and reported by MaineSail. The 6-volt golf cart batteries, 230 amp run about $85 a piece around here. They also have Group 31 AGMs for around $166 and other deep-cycle bargains.

[four winds]

I'm not a Sam's Club member, but I can't seem to find any batteries on the web site. About 20 miles from closest store.

Can't figure out what I'm doing wrong.

[Talisker]

Thanks for all the tips and web references, certainly some food for thought. I have also learnt how much I mistreat my batteries.

I suppose it all comes down to what sort of use and pocket depth. I have just had the battery (gel I believe) replaced in my Audi A6, 300 Euros plus Ouch!

I have definitely decided that the Gel type is not for me, as I have no intention of replacing my charging system. Over here in Europe the AGMs are about twice as expensive as lead/acid, but I have not read that AGMs are twice as good as lead/acid.

There are some sealed lead/acid on the market so that solves one disadvantage, I guess.

Think I'll just go with the sealed lead/acid, and be done with it!

Thanks again!