AGM vs wet cell batteries

[eze2bme]

I know this has been discussed before - BUT - now that some time has passed - what is the joint opinion. Does an 8D AGM last longer than the wet cell for starting batteries in banks of two? My wet cells last about 4 years and then a cell seems to short and kill the batteries. The theory of AGM would suggest that cells wouldn't short out or need watering since they are sealed - but that's just theory. From what I see on here even the AGM's seem to last only 4 years. Maybe the gell cell is a better way to go?? Thanks for any imput.

 

[Jaxfishgyd]

I replaced my four 8D batteries with group 24's 12 years ago..... I got 6 yrs out of them and replaced them a year ago and I like them....A LOT easier to replace and have had zero problems at any time...
I have the rear starboard bank set up to run the inverter but also have the bank on an 'on/off' switch so I can use it in tandem with the front bank if needed....
But I also only have a 43' and use the inverter mainly for the refrig and the TV system at night if we're not running the generator when away from the dock.
I get mine from "Battery Depot" and paid $76.00 per battery last year due to the fact I was buying 12 at one time...
And I check the batteries every month (even though it's a PITA as they are located on the outside of the engines)

 

[Pascal]

On the boat i run We have 3 banks of 8D AGMs for house and engines, plus a 4D for each genny and none have lasted beyond 5 years, which pretty much what I get from the lead acid golf cart batteries on my own boat...

On the plus side they are maintenance free

 

[Boatsb]

I pulled a set of 6 year old lifeline agm batts and used them for almost 3 years in my boat before they died. Just delivered a 8d deep cycyle agm the other day. Almost 50 pounds heavier than a standard one

 

[rwappleton]

Tom,

Call Ken. That is what he does for a living. he should be able to hook you up on pricing too.

Russ

 

[mrdeepseafisher]

some of you may have read that I am currently having battery issues so this is a question I have also regarding AGM vs lead acid. So here is my question.

I am having trouble finding AGM 8 volt locally, must order. Also each AGM is 300.00/each, so I could buy 4 AGMs for 1200.00 or replace all 8 for 800.00. I did find today 8 volt lead acid batteries locally.

If all eight are replaced I can change the settings on my charger to lead acid and be back to two new banks with the proper charge sequence for lead acid.

I have been thinking about installing an inverter and could use the current good AGMs (4 total) for the inverter.

Based on this thread am I reading that there doesnt seem to be much advantage to AGMs?

 

[Ross Macdonald]

With AGM batteries for your inverter system it's all about how many times you cycle them down to say 60% then recharge them. We have 4 8D AGM batteries that are dedicated solely to the 24 volt inverter system and we are on a mooring every summer for about 70 days. So obviously they are cycled down 140 times in the summer (during the night and during the day when the genset is off.) So we have gotten about 4 years out of these batteries. When you do research on these batteries it is all about how many times you cycle them. I have to replace the 8 volt lead-acid batteries in the OEM starting and house banks about every three years. So I don't see a great advantage to the AGM's other than I don't have to check them every thirty days. The AGM's for our inverter are in a special rack in the utility room and consequently are almost impossible to service. The group 31 AGM's I have for the gensets seem to last 5 years. Just my personal experience....Ross

 

[GJH]

some of you may have read that I am currently having battery issues so this is a question I have also regarding AGM vs lead acid. So here is my question.

I am having trouble finding AGM 8 volt locally, must order. Also each AGM is 300.00/each, so I could buy 4 AGMs for 1200.00 or replace all 8 for 800.00. I did find today 8 volt lead acid batteries locally.

If all eight are replaced I can change the settings on my charger to lead acid and be back to two new banks with the proper charge sequence for lead acid.

I have been thinking about installing an inverter and could use the current good AGMs (4 total) for the inverter.

Based on this thread am I reading that there doesnt seem to be much advantage to AGMs?

It sounds to me like you are using very small batteries for this purpose, entailing starting and house use. When you say "replace all 8" is that total or per side? Anyway if you are considering using 8 volt LA (you know AGMs are LAs too) that cost 100 bucks apiece, hat would give me a lot of pause.. there's no free lunch in this game. If you think you will match the performance of a Deka that cost about three times that, or a Rolls that costs 5 times that...

I looked through the Discover site and their 8 volts all appeared to be golf cart types and none weighed over 95 pounds, most much less. For reference sake my Rolls batteries in the OEM form factor weigh 139 pounds. I do have a set of 8v195s that are solely used to start the starboard engine and are so configured, they weigh about 90 lbs but are never deep cycled; I don't have any illusions of them lasting a long time, though on their third year and cranking very nicely. I still feel like I am "Gomering" a bit on that bank. I know people who don't start their engines very often who "get away" with using golf carts.

I'd also submit that not all AGMs are created equal, which is why Lifelines and Odysseys cost so much more than the lower end Chinese stuff, and at least anecdotally last longer according to a very non-scientific survey of people who have tried both.

Personally I only have one AGM among the 15 big batteries on board, to start the generator and feed some small intermittent 12 volt loads (macerator pump, holding tank gauge, etc). I was feeling kind of profligate that day and it was on sale (Sears Platinum Plus marine, made by Odyssey).

All my batteries are very easy to service and the theoretical payback time in life span is so long I don't care about it. If there was an AGM 8 volt equivalent to the Rolls or Dekas, I might of tried it. The Rolls cost about 500 bucks a piece so I was in the ballpark anyway. Without knowing what kind of use your boat has had in tha past 5 years, your lifespan on the batteries per your other post doesn't sound bad though. Didn't you just buy this boat in the last year or so?

 

[Fanfare]

I am into my fourth year on Interstate AGM 12v 8D batteries, no problems so far. My batteries are under the galley in my generator room. This gets pretty hot when operating the generator and required me to add water to my batteries about monthly. Since I have a total of five batteries this is a lot of cells (even though I was given a nifty battery filler pitcher that automatically fills each cell to the top without my having to look inside!). With the AGMs I don't have to use water at all. I worried that the generator heat might dry out even AGMs but enough time has passed for me to say apparently not.

I had a 1992 Miata that came with an AGM battery. When I sold that car in 2005 it still had the original battery, which never failed to start during the entire time I owned it. Hence my decision to try AGMs on the boat.

If you really have extra boatbucks, Rolls now has AGMs. I look forward to someone reporting on these!

 

[ian w]

As an aside is it acceptable to use Watermaker (reverse osmosis )water in batteries I am in the islands -no distillrd in local stores ian w

 

[mrdeepseafisher]

Hey George,

Thanks for the input. Yeah I know that AGMs are lead acid also. I guess I don't take time to fully provide all information, most of this posting is done while elbow deep in other projects as well as trying to answer work phone calls while being on "vacation" and I am lucky if I get about half of what I am thinking in the post. In this case I am using the term AGMs as the sealed glass mat batteries versus the classic wet unsealed batteries.

I have spent two days getting advice from several boating "experts" in the Wilmington area and I am not talking about the guys here at the dock. The range of opinions is impossible to convey here. I second guessed myself on reverting back to the wet batteries that need to be checked monthly based on a previous post one of the local sales persons saying they could provide an eight volt for about that price. In actuality, they couldn't come close to that price.


Yes we have owned the boat for a little over a year and a half but have been aware of, and on the boat for over three years which is one reason we ended up with this boat (we knew a bit about it). The PO before us used AGMs for both banks (4 8 volt on each side) The port bank is used for starting and provides power to all 32 volt systems on board. The starboard bank is used for starting only. Port side is Evergreen and starboard side is Fullriver. Each battery is about 80-85 lbs.

I had called Sams a couple of days ago and they finally got back with me early today. I explained what I had in the boat and they sent me to a regional rep for Fullriver. I have four new 8 volt sealed AGMs that should be here on Monday. Folks at Sams and the battery rep seemed to think that going back with the Fullriver would be the best option. Was able to get them for about 300.00 each. Which looking online prices seemed to range from 300-450 a piece.

I think the AGMs deep cycle are on the port bank due to the fact they are used for the 32 volt systems as well as starting the port engine. I did consider moving the starboard batteries to the port side and purchasing starting only for the starboard side. I mentioned this to both the Sams folks and the fullriver rep and they didn't see the need for that.

We have never had any issues with starting the engines until earlier this year. I personnally think that we "killed" the port side last year when we were in Murrells Inlet for a week with too many family members onboard.

The inlaws wanted to have a birthday party on board and we had almost 20 people here. Had little hands running throughout boat and didn't realize that many 32 volts items had been turned on, including lights in the engine rooms, salt water washdown pump in cockpit, etc. I got up next morning frantic when the heads wouldn't flush. (I think I even posted something asking for help)

After looking boat over I found that the port bank was basically fully discharged and the breaker for the battery charger had been turned off as well as others. I thought I would blow a gasket but wife did it for me. We sent everyone to the beach house and got them off boat. It took a day and a half to get the port bank charged to the point it would start the port engine. Batteries have never been right since last year.

I think I am taking Pascal's advice and looking for a panel/display that can monitor and alarm when conditions deviate form normal. I also have the charger manual out tonight and will be checking to see if it may have any issues.

As always thanks to everyone for the help. I took the day off today and went to Southport to see Magnawake's boat as he is just down the way from me. Back to boat work tomorrow.

 

[Pascal]

At the dock or on generator, the number of 32v items turned on or used should not make a difference since the charger should provide enough juice. You may want to make sure the charger is working and particularly that the wiring from charger to the house bank is nice and clean

A good location to put in digital meters is to the right of the helm, by the stairs. That's a position where you can easily see then form the saloon and also every time you go downstairs.

I like the blue sea meters, other for DC and AC. Both can cycle between amp and volt. Easy to instal, just a round hole and that spot to the right of the helm make it easy to wire down to the ERs

 

[fissioneng]

FWIW, I have two 12 volt Exide Nautilus deep cycle conventional 8Ds for my port bank that will be 6 years old in Sept. I check water and SG regularly. I don't take them down much since we run the generator all the time for the AC. Because of this, AGMs don't offer me much and also would force me to change my alternator regulator if I went that way.