AGM vs GEL battery replacement

Bob James

Bob James

.
May 3, 2008
190
Catalina 310 Catawba Island
I have two 4-D AGM that are in their 9th sailing season. They seem fine - they are on dock power charging most of the season and are seldom off charge for more than two days at a time. Do you think it would be a good idea to do a preemptive replacement?

I have an economic incentive to buy this year due to an employee discount at WM that is about 50% on either type that may not be availabable in the future.

Is there any consensus re AGM or GEL? I have had such a good experience with AGM and would tend to lean that way.
 
JK_Boston_Catalina310

JK_Boston_Catalina310

.
Nov 18, 2010
2,441
Catalina 310 Hingham, MA
bobjames said:
I have two 4-D AGM that are in their 9th sailing season. They seem fine - they are on dock power charging most of the season and are seldom off charge for more than two days at a time. Do you think it would be a good idea to do a preemptive replacement?

I have an economic incentive to buy this year due to an employee discount at WM that is about 50% on either type that may not be availabable in the future.

Is there any consensus re AGM or GEL? I have had such a good experience with AGM and would tend to lean that way.
Click to expand
I have not been big on AGM since I read Maine Sail's musing on the subject. http://forums.sbo.sailboatowners.com/showthread.php?t=124973

Sounds like for you use you might be better off by saving some bucks and going with 6 volt flooded. But they will require adding water.
 
Maine Sail

Maine Sail

.
Feb 6, 1998
11,672
Canadian Sailcraft 36T Casco Bay, ME
bobjames said:
I have two 4-D AGM that are in their 9th sailing season. They seem fine - they are on dock power charging most of the season and are seldom off charge for more than two days at a time. Do you think it would be a good idea to do a preemptive replacement?

I have an economic incentive to buy this year due to an employee discount at WM that is about 50% on either type that may not be availabable in the future.

Is there any consensus re AGM or GEL? I have had such a good experience with AGM and would tend to lean that way.
Click to expand
The West Marine/East Penn AGM & GEL batteries are rated by East Penn (the manufacturer of both) for the following # of lab rated cycles.

GEL = 1000
AGM = 300

Which one do you suppose is the real deep cycle battery?;)

If you want AGM buy Lifeline or Odyssey as these are the premium AGM batteries.

If you want GEL the East Penn product is great.
 
Alansails

Alansails

.
Oct 3, 2011
827
Anam Cara Catalina 310 Hull #155 155 Lake Erie/Catawba Island
We have the 2 4D Batteries and I have no idea as to how old they are, so I called the broker and asked him to check with the previous owner, no paperwork was provided,but like Bob, we are hooked to shore power most of the time and when we are not even when running the fridge for half a day it does not "Kill" the battery. The broker and Battery reps we met at the Chicago boat show advised that the lifeline is the maintenance-free way to go. They advised ordering on-line and having them delivered But since Bob has the DEEP DISCOUNT, at WM that has to be the least expensive option.
 
I

iSailor

.
Oct 17, 2011
221
Catalina 310 USA
FYI - One of my 4D AGM batteries decided to kill itself this year. When we arrived at the boat, there was a horrible sulfer smell. You could hear the one battery "boiling" internally and the outside casing was extremely hot. Shore power was hooked up and the battery charger on. Even after the power was cut, the battery was still boiling due to the other battery feeding it juice. After the batteries were disconnected from each other, the boiling finally stopped.

Not sure about the age of the battery, it was from DEKA. Boat is a 2001. Last season I remember a lot of corrosion on the battery terminal, not sure if this was a sign it was going bad or not. Replaced with 4D's from Interstate Battery. WM was too costly.

Not sure what would have happened if we decided not to come down that weekend.....
 
JK_Boston_Catalina310

JK_Boston_Catalina310

.
Nov 18, 2010
2,441
Catalina 310 Hingham, MA
Alansails said:
We have the 2 4D Batteries and I have no idea as to how old they are, so I called the broker and asked him to check with the previous owner, no paperwork was provided,but like Bob, we are hooked to shore power most of the time and when we are not even when running the fridge for half a day it does not "Kill" the battery. The broker and Battery reps we met at the Chicago boat show advised that the lifeline is the maintenance-free way to go. They advised ordering on-line and having them delivered But since Bob has the DEEP DISCOUNT, at WM that has to be the least expensive option.
Click to expand
I think "maintenance-fee" is the wrong term to use. They may be reduced maintenance in that you don't have to water them. But read what Maine Sail has posted about AGM batteries. If you don't maintain them with proper charging cycles and equalizations you are just throwing your money away. Also you can seriously reduce their cycle life if your charger and alternator aren't up to the job. I don't know what you have as all of the boats are slightly different in that manner.

For me, I will go with flooded 6volt golf cart batteries until some new technology comes along that is affordable, as easy to maintain and less picky about charge source but I suspect that will be a long time from now.
 
Stu Jackson

Stu Jackson

.
Feb 26, 2004
22,776
Catalina 34 224 Maple Bay, BC, Canada
Alansails said:
...but like Bob, we are hooked to shore power most of the time and when we are not even when running the fridge for half a day it does not "Kill" the battery...
Click to expand
The difficulty with this approach is that one rarely knows when a bank is dead until "you're out there." Keeping them "charged" on shorepower ALL THE TIME is also not good for banks. Constant float creates sulfation.


iSailor said:
FYI - One of my 4D AGM batteries decided to kill itself this year. When we arrived at the boat, there was a horrible sulfer smell. You could hear the one battery "boiling" internally and the outside casing was extremely hot. Shore power was hooked up and the battery charger on. Even after the power was cut, the battery was still boiling due to the other battery feeding it juice. After the batteries were disconnected from each other, the boiling finally stopped.

Not sure about the age of the battery, it was from DEKA. Boat is a 2001. Last season I remember a lot of corrosion on the battery terminal, not sure if this was a sign it was going bad or not. Replaced with 4D's from Interstate Battery. WM was too costly.

Not sure what would have happened if we decided not to come down that weekend.....
Click to expand
This is a perfect example of the first quote. Maine Sail has mentioned many times: "Batteries don't kill themselves, they're murdered."

Perhaps this skipper did the right thing, but...

And 4D batteries are NOT true deep cycle, and they're back killers.

Really, I suggest that those of you who are ALWAYS on shorepower do a simple test, maybe even once a month: FULLY charge your house bank and then DISCONNECT from shorepower.

Then, you will see what is really happening the next time you come down to the boat.

Most folks seem to get it backwards: "My bank was fully charged when I left the dock."

The real world issue {for those of you who are NOT marina hoppers (and this could be many of you and is a description of activity - how YOU use YOUR boat, and is not meant in a negative way at all} is that the challenge is to spend a night on the hook or unplugged, and run your normal loads. In MOST cases, a good daily draw with a fridge is +/- 100 ah.

Like this:

Record of Daily Energy Use of 100 ah per day:

http://c34.org/bbs/index.php/topic,6353.msg41471.html#msg41471

One must work THE OTHER WAY: "How does my system work when the bank is DISCHARGED for a night or two," NOT how it works when it's full to start off with.

This is for those of you who prefer to disconnect from shorepower, whether it be a trip or an overnight at your favorite anchorage.

Give it a try sometimes, you might find out things you never knew. :dance:

Maine Sail's discussion of AGMs is VERY worthwhile reading. The main point is that they fail without warning. IN many boating forums, recently, I've seen questions like, "My AGMs are 9 years old, should I replace them?" It's kinda amazing, the same question in four different forums. In all cases, I refer them to Maine Sail's link, and this one, too:

AGM Battery Issues and the Blue Seas Dual Circuit Switch (from Maine Sail) "DARN AGM Batteries"
http://forums.catalina.sailboatowners.com/showthread.php?p=848465&highlight=darn agm

That is why, for most of us frugal boat owners, AND who have reasonable ACCESS to our batteries, wet cell remains the most bang for your buck way to go. Others, who have difficult or NO access, yup, AGMs, but I'd go gels first.

Your boat, your choice.

All the best,

Stu
 
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