AGM Battery Questions

What advantages are you looking for to be worth spending double the money?
No maintenance and fast charging are the primary advantages. Do you spend time off grid?
What make and model converter do you have?
Any issues to avoid the wet cell golf batteries?

It is unlikely that any one 12V battery (AGM or otherwise) will have the capacity of two 6V golf cart batteries. Check the amp-hour ratings to compare.

Do you "need" spill proof type battery like AGM?

To me if you are looking for the most Ahr for your money those AGMS are extremely expensive.

You can get Sams GC2 FLA batts with 210Ahr for $80 per 6V battery vs $210 (plus $32 shipping) per Amstron 210 Ahr 6V battery.

Sams 6V FLA costs $.38 per Ahr and Amstron is $2.42 per Ahr.

Something else to consider, there are several types of AGM, one is only good for 80% or less DOD (Depth of Discharge) and the other is good for 50%-60% DOD.

Compare that to Sams FLA GC2 which can be easily discharged down to 20% DOD without harm (although at somewhat expense of some of the life).

FLA can also be discharged 100% and as long as you recharge as soon as possible it will "recover" to some sort of usable capacity.

AGMs if discharged to 100% will result in expensive door stops (even if recharged immediately)

Granted AGMs are considered Maintenance free, that same characteristic can also be a downfall in the fact that if you overcharge a AGM it will vent the pressure and when that happens you lose electrolyte and can not add new electrolyte.

With a FLA if you overcharge it you can at least add water to it..

There are a lot of pros and cons to both types..

To me, watering my batteries is not a chore, I do it once a year and only takes 10 minutes at the max. So far no corroded terminals but I use a product called No-Alox which is a grease used for connection aluminum wire to copper wire.. It stops oxygen and moisture from getting to the connection and hence prevents corrosion. Been using that for years on my vehicle batteries with success..

You just need to ask yourself if you just simply want (and don't mind paying for)the "cool factor" when you tell folks you have AGMs.

You need a smart three stage charger where you can turn off any equalization functions. Same applies to any solar charging systems. AGM do not like being charged at 15+ volts.
At the rate my original 6V were rusting the battery area they would be dragging on the ground by now if I had not switched to AGM. You need to do a lot of off the grid camping to justify the extra cost IMHO.

I love the cleanliness. Just dust them now and then!

AGM v flooded 2011

2oldman wrote:
I love the cleanliness. Just dust them now and then!

AGM v flooded 2011

I need to take some photos of my FLA GC2s, they are so spotless you can eat off them and I don't do ANYTHING to them other than let my PD9160 with Charge wizard take care of them 24/7 when not camping..

I am not buying into the cleanliness thing..

I'll offer you an example of how and why I chose AGM

I needed a spill proof battery

The battery is placed alongside my bed, dealing with fumes, and corrosive liquid was out-of-the-question. The battery must remain pristine clean and dry with a dusting needed every week.

The battery, a single group 31 has to charge faster, a lot faster, than a flooded group 31 battery. Sometimes power returns for a half-hour and as much energy as possible has to get stuffed back into the battery. This one accepts 71 amperes without a whimper. A standard 31 balks at around 42 amperes. If I had more charger the AGM would accept over 90 amperes, which is my goal.

The battery is going to see occasional 89-90% discharges. I don't like to do that to a battery but rather than stare into blackness in 90 degree heat and 70 percent humidity, the battery is going to have to work to light my bedroom, power a Fantastic fan, and my BiPAP. This battery is heavy but it has to do "portable" duty to hotel rooms, and even inside my car if I decide to spend an uncomfortable night parked at a gasolinera. If will have light, fan, and BiPAP

It is silly to choose AGM solely on the fact they can be recharged faster if the rig is a power pole addict and never boondocks. Similarly having a battery bank that can accept a 200 amp charge rate but only having a 50 amp charger and a generator that stalls overloaded at 40 amps is not a wise balance. The fast recharging advantages only come when all of the criteria is met. Generator + charger. Big on both. A 4,000 watt generator and 130 ampere charger would be considered "moderately effective" for such a bank.

Even though I do not use the feature, the AGM battery provides a lot more CCA rated power to run high demand loads, like a microwave. But that takes a huge pure sine wave inverter and copper cables with the conductor as large as your thumb in order to make sense.

AGM is cleaner than flooded, and corrosion becomes a non-issue.

You are thinking about purchasing off-brand batteries. Care must be taken to not end up with engine starting batteries with labels replaced with deep cycle. Usually GC three cell AGM batteries are made with heavier plates. But there's a lot of garbage out there with .060" thick positive plates.

In my opinion it's best to bite the bullet and go with a proven line like Lifeline or Fullriver. Yes the price hurts. But getting screwed hurts more.

Hope This Helps

My question regarding agm's is;

although they CAN be charged faster, DO they charge faster???

... comparing two 220Ah 6v fla, to two 220Ah 6v agm, at the same soc, using the same 40a charger on each, with Vabs at the recommended setting for each, how much faster would the agm's charge to full?

Charge ACCEPTANCE is key. When regular battery absorbsion limit is reached and amperage starts backing down, the AGM will still be maxxing the charger. This phenomenon is pronounced and prolonged. A greater amount of WATT HOURS in (or kWh which is more accurate).

So charger size is a vital component of "Do they charge faster?" You need to understand the voltage/charging curve in relationship to your charger. A 20 amp charger wouldn't do a squat worth of difference nor would a huge charger on a titanic battery bank. Fifty percent of ampere hour rating MINIMUM to take full advantage of an AGM battery's charge receptivity. 100 amperes for a 200 amp hour rated AGM bank. Two hundred amperes to take full advantage of a 400 amp hour bank.

An AGM user here. I have a single 4D AGM. It gives about the same AHs as 2 6V in series. AHs are AHs no matter how you arrange them.

I like having 2 terminals to keep clean instead of 4. No rust or corrosion in my battery box area. My 4D has had 5 seasons so far. I expect at least another 3. For 6 months of the year my AGM sits, disconnected, with no battery minder. Nothing. In less than 1/2hr charging it is ready to go for the next season.

Yes it was expensive, but I like the peace of mind knowing that I have almost the best made & most reliable when I am out dry camping miles from any Walmart where the cheap 6V wet cells come from.