AGM battery

[Donald]

I was at Sams Club looking for a "house" battery for my boat. It seemed that a group 24 AGM had more CCA than a group 27 flooded cell. And this AGM was a deep cycle, not a starting battery.

So it seemed to me that the most CCA per dollar was in an AGM and I did not think that was true.

They were East Penn (Duracell) batteries.

I was disappointed to see batteries almost 1 year old. The salesman said the company comes once per quarter and only pulls batteries that are over 1 year old. Any battery, not just AGM. IMHO, 6 months is the max it should be on the shelf.

Interesting that the batteries over 1 year are "repurposed" meaning they are checked out, charged and sold as used batteries at some places. (They leave Sams, but this is what I was told happens to them.)

 

[stockrex]

Originally Posted By: Donald
I was at Sams Club looking for a "house" battery for my boat. It seemed that a group 24 AGM had more CCA than a group 27 flooded cell. And this AGM was a deep cycle, not a starting battery.

So it seemed to me that the most CCA per dollar was in an AGM and I did not think that was true.

They were East Penn (Duracell) batteries.

I was disappointed to see batteries almost 1 year old. The salesman said the company comes once per quarter and only pulls batteries that are over 1 year old. Any battery, not just AGM. IMHO, 6 months is the max it should be on the shelf.

Interesting that the batteries over 1 year are "repurposed" meaning they are checked out, charged and sold as used batteries at some places. (They leave Sams, but this is what I was told happens to them.)


drive/call other sams club they might have fresher batts,
sams sells a lot of house batts beginning of summer,
get the 2 6volt will last longer and give you more capacity, just charge them often,
the agm will last long also but capacity is lower (from what I remember when I looked at them for my APU).

 

[Donald]

Originally Posted By: stockrex
Originally Posted By: Donald
I was at Sams Club looking for a "house" battery for my boat. It seemed that a group 24 AGM had more CCA than a group 27 flooded cell. And this AGM was a deep cycle, not a starting battery.

So it seemed to me that the most CCA per dollar was in an AGM and I did not think that was true.

They were East Penn (Duracell) batteries.

I was disappointed to see batteries almost 1 year old. The salesman said the company comes once per quarter and only pulls batteries that are over 1 year old. Any battery, not just AGM. IMHO, 6 months is the max it should be on the shelf.

Interesting that the batteries over 1 year are "repurposed" meaning they are checked out, charged and sold as used batteries at some places. (They leave Sams, but this is what I was told happens to them.)


drive/call other sams club they might have fresher batts,
sams sells a lot of house batts beginning of summer,
get the 2 6volt will last longer and give you more capacity, just charge them often,
the agm will last long also but capacity is lower (from what I remember when I looked at them for my APU).



I was not clear, I got a fresh one, it was 2 or 3 back from the front.

My point was it seems this AGM deep cycle group 24 has more CCA than a group 27 flooded cell battery. The group 27 is significantly larger in footprint.

 

[JHZR2]

Originally Posted By: Donald


I was disappointed to see batteries almost 1 year old. The salesman said the company comes once per quarter and only pulls batteries that are over 1 year old. Any battery, not just AGM. IMHO, 6 months is the max it should be on the shelf.



Based upon what? Internal resistance and self-discharge are lower in AGM batteries. Stores are usually kept at pretty decent temperatures, around 75F. So long as they were charged once in a while, I see no issue. Optimally they would be float charged, which we know isnt the case, but neither is it when put into service usually.

Of course it is smart to look for the newest battery, simply because it is the newest one. But an AGM on the shelf still showing good voltage wouldnt scare me much.

Originally Posted By: Donald

My point was it seems this AGM deep cycle group 24 has more CCA than a group 27 flooded cell battery. The group 27 is significantly larger in footprint.


Apples and oranges though. What is the Ah rating of each?

 

[rfeir]

An AGM battery may require a higher charging voltage than a wet acid battery. Thus both the house and starting battery should be AGM and the regulator may need to be changed.

 

[[email protected]]

I bought my marine AGM's from Sams Club 2 years ago and put them through the test (overnight every weekend with the d/c refrigerator running at max, tv on an inverter, anchor light on overnight, etc). They are GREAT batteries for the $$

 

[SubLGT]

There is at least one manufacturer of AGM batteries (I can't remember the name) claiming a shelf life of two years under favorable conditions.

Deka claims their VRLA batteries (gel and AGM) have a shelf life up to 7 times longer than a wet cell antimony alloy deep cycle battery.

 

[wrcsixeight]

AGM batteries always have significantly higher CCA ratings than flooded batteries.

Most people think this relates to more capacity and think AGMs are more powerful, but this is not to be. Batteries like Optima might have more CCA than a similar footprinted flooded battery, but about 25% less overall capacity. But marketers have duped the masses again.

Even rectangular AGM batteries like Odyssey are rated slightly lower capacities than their flooded counterparts, and weigh more to boot. But whereas a flooded group31 dual purpose marine battery might have 700CCA and weigh 62 pounds and have 115 amp hours, a Odyssey group 31 will have 1050 CCA weigh 78 lbs and be rated for 105 Amp Hours capacity.

A deep cycle battery can be used for starting if it has enough CCA, and will be more durable if the vehicle is the type to be short driven with lots of stereo use with the engine off.

Best way to maximize the longevity of any battery is to make sure it gets an occasional true full charge, and the vehicles charging system is not very good at this task despite the prevaling opinion that alternators are instant magical battery chargers.

 

[DBMaster]

^A dealership parts guy told me about this maintenance charging quite a few years ago. I connect a trickle charger every now and then, but it always lights up "green" and shows the battery is fully charged so I'm not sure what good it's doing.

I found that AGM batteries (Optima Red Top for me) were far preferable to conventional in my 89 Accord. The one I bought in 2002 lasted six years and when it went bad it continued to start the car - it just cranked over more slowly. That was DOUBLE the life span of any conventional battery I had in the car since new. The one I bought in 2008 was four years old when I wrecked the car. Lots of people on here complain about Optima batteries having reduced quality in recent years. I don't know if that was the case in 2008, but even the four years it had gone by 2012 when I sold the car was still longer than any previous conventional battery.

I think they are worth the extra money for the warning they give you alone. All other batteries I had would simply fail to start the car when they went bad.

 

[wrcsixeight]

DBmaster,

After engine shutdown it will take some time for a battery's surface discharge to dissipate. Hooking the maintainer, or almost any smart charger to it when the battery is reading over 12.8 volts, will cause the charger to go into float/maintenance mode. I often have to trick my chargers by loading the battery till voltage drops below 12.8, then they will take 12 or 25 amps, versus the 1.3 amps that it takes to hold 13.2 when it is started at 12.9.

Batteries need a certain time in the mid 14 volt range to shoehorn in all they can take. It is debatable if 13.2 for 24 hours can do what holding 14.5 for 2 hours can do.

The green lights lie.

 

[Donald]

I returned the AGM and got a lead-acid group 27. Decided not to mix battery types for the starting and house battery.

For people who go to a AGM battery in their car, how do they adjust the alternator so it charges to the proper voltage for an AGM battery which is a little higher than a lead-acid.

 

[DBMaster]

I hooked up the charger last night and actually got a yellow light on it. It took a couple of hours at the 2A setting for it to go green. I think 2-3 times a year might be often enough to do this.

My charger is a little Black & Decker thing that chargers at either 1A or 2A. I bought it to just hook up overnight every once in a while.