AGM batteries, what's your opinion?

[dan_erickson]

I am starting to do research on AGM batteries for my two cars and want to ask BITOG crowd what brands to buy or stay away from. I know that most seem to be made by JC, some Deka, some Exide. I am not in dire need of the batteries right now so I am hoping to catch a sale before I buy.

Now the reason I am looking at AGM batteries, and forgive me if I am wrong, is because the Grand Prix sits for long periods on time in the garage and the Honda has a stereo that will draw some juice.

I guess what I am asking first, is it worth it to pay the extra money for am AGM battery? Second, what major brands should I look at and not look at?

 

[jimbrewer]

I can't remember the ins and outs at the moment of AGM vs. flooded lead acid.

If you garage your car I can recommend using a float charger. Even if you only use it once a week on your daily driver, I think you would see an improvement in battery longevity. Mine is about halfway through its service life after five years after getting off to a bad start with my low-mileage driving habits.

I'm guessing that you could at least defer the new AGM long enough to pay for the float charger.

Of course you would want to make sure your float charger is compatible with AGM for when you do make the change.

 

[NHGUY]

An AGM can take a long drain and come back faster,better.An AGM can "cycle" many more times than a conventional battery....Batteries have a limited "starting"(cranking drain) life and an AGM can increase that by double or triple.An AGM plate cannot technically "short" as there is a fiberglass acid absorbed separator between them.All that said,with an AGM twice or + twice more expensive,you may not get the full advantage for your dollars spent.

 

[barryh]

All batteries will be slowly discharged by the quiescent current drawn of every modern car in storage and only the AH capacity will differentiate how different batteries are affected by that discharge.

But batteries discharge themselves in another way due to the internal chemistry. The big difference between AGM and standard wet cell batteries is that AGM have a vastly lower internal self discharge rate.

So for example on a vehicle that has zero current draw like an old classic car without a clock the AGM can be left for months at a time without loosing any significant charge where as a standard battery would be substantially discharged over the same period.

Even when the vehicle has a quiescent current draw the total discharge rate will be lower with an AGM so it can be left for longer before being re-charged.

 

[Trav]

My cars sit most of the year. I don't even put a couple of thousand miles on any one of them, my 07 Sky bought new has only 5,xxx miles on it.
The GP battery was replaced by the first owner with a Die Hard sealed top in 2003 and is still in fine shape, the Sky's was replaced in 2010 with a Die Hard sealed top and is also fine, in fact all the cars using these sealed top Deka made batteries do not require replacement very often sitting or not.
The only ones that didn't do well were the AA gold and yellow ones from Wally's.

The point here is there are 7 cars here that sit most of the time and don't go through batteries (none are AGM) so its either how I maintain them, the condition of the charging circuit or its the brand. Maintenance is zero, I do not use a maintainer on them only the tractor, snowblower and lawn mower, I do lock them by hand so the alarms don't arm and draw the batteries down and every few months or if the battery is 50% give them a slow charge.
The GP never gets charged, sitting from Nov- April the battery is still at 70% and fires right up. Friends in the parts business tell me the warranty replacements on AGM batteries is horrendous, lots of early failures. I can neither confirm or deny that but if a good flooded batter is holding its own after almost 14 years I cant see how there can much benefit.

Try locking the car by hand not the key fob, battery drain on the GP will drop to almost nothing which really saves the battery. Now when I do need a battery I get Die Hard with the code for Deka made on them not Johnson.

 

[UncleDave]

For me the choice is dependent on a few factors.

For a regular auto with access to current to run a maintainer I wouldn't bother, a decent maintainer will extend a lead acids life to 10 years or more.

IF you can't plug in a maintainer an AGM makes sense as it will self discharge much slower as has been said already.

I go with AGMs if I need to mount in an enclosed area and can't vent hydrogen, or need the ability to charge quickly as their low resistance lets you slam current into them.

Otherwise regular wet lead acid typically have a higher cycle count, and are cheaper if you can keep them on a maintainer.

UD

 

[901Memphis]

If the parasitic draw is great enough they need to be recharged no matter matter the chemistry

 

[Wolf359]

The original AGM battery in my Mercedes is still going strong at 9 years. The instrument cluster can give you the current voltage and it's been doing fine lately so I haven't bothered to replace it yet. Advance Auto typically has good coupon codes to take the price down about $50 so they're not too much more than regular batteries plus they last longer and you don't get the corrosion on the terminals you normally get on flooded batteries.

 

[CrAlt]

Good maintainers(tenders) definitely seem to extend the life of regular lead acids from what I have found. I have a NAPA "legend" GP75 battery thats going on 9 years now. 2 others that are 5 years old. I used to go through batteries like crazy in my cars that sit.

 

[slacktide_bitog]

Napa's batteries are made by Deka, and Deka's batteries are the best. Sears/Kmart DieHard is now Deka, too. Any battery made by Deka will be good, AGM or otherwise.

AAP and Autozone batteries are made by JCI.

Go for the best price Deka-made battery you can get.

 

[UncleDave]

Originally Posted By: 901Memphis
If the parasitic draw is great enough they need to be recharged no matter matter the chemistry


For sure.

As long as the OP understands the self drain loss, and the parasitic loss are additive.

UD

 

[bioburner]

I will stick to wet cell unless I get another Jeep and decide to go bouncing around or try and put a car on the race track.
I can go to the salvage yard and get 1 year old batteries or less, name brand for $30. After Xmas storm there should be a pallet of them with accidents reported at several hundred per day. Ba humbug.
Charging vehicles with a maintainer or monthly will help keep them going well past 5 years at least in my environment.

Wolf359 having good luck with his and the vehicles charging system is probably tweaked for the AGM

 

[SHOZ]

AGMs are all I've had for the last 15 years. Still have some that are 15 years old. Both Hyundais came from the factory with AGMS. It's the only kind of battery I would have. But I hesitate at the spiral cell design.

I just disconnect them if they are going to sit for more than a month. And they quickly recharge; not much use for a maintainer unless you want to keep the battery hooked up and taking care of the normal off current draw.

I have one in the mower and it does not even take 5 minutes in the spring if I boost it, I generally don't and it's +10 years old.

 

[HangFire]

AGM's are great if you limit the charging voltage as per spec.

No one does this in cars.

Worked in a place that went AGM crazy for a while and bought them for all experimental and service vehicles with no voltage limiters. 2 years later they were all in a pile by the garage door, waiting for Purchasing to go through the motion of warranty claims. Sat there for years after several different factory reps explained charging voltage.

 

[Donald]

If the battery manufacturers felt the AGMs were significantly better they would give a better warranty. But they do not.

If you look at the cost per month to have a battery that will always start your vehicle, my guess is the Walmart MAXX would win out.

I am not convinced that all charging systems will be optimal for an AGM battery. Given that the plug-in charges have a setting for AGM and flooded, I assume it would be best if the vehicle's charging system did also. Only a couple of high end vehicles, maybe BMW or Mercedes.

 

[SHOZ]

I see no voltage or charging problems with AGMs. I have a cheap 30 year old 2/6A charger. But how often do you use a charger? My cars keep the voltage at 14v when fully charged, a little lower in summer, and they charge the battery after a start at about 14.5-14.3V.

Both are OEM batteries but two different manufactures.

 

[wrcsixeight]

People tend to lump all AGMs into the same category and all having the same characteriestics.

But there is a huge Difference Between the Deka Intimidator and say an Odyssey,in both CCA figures and self discharge, and what voltages/amperages are recommended when recharging.

Much depends on teh usage of course, but a deeply depleted Odyssey wants a minimum of 40% of the AH rating. 40 amps per 100AH of capacity and are then to be held at 14.7v for 4 more hours.

The Deka Intimidator says no MORE than 30 amps per 100Ah of capacity and 14.4v is the absorption voltage.

There is nearly a 50% price difference in these two batteries too, so the Lumping of these two together is unwise.

East Penn/Deka make a great battery, but the intimidator AGM is the most rebranded AGM in north America. its self discharge is not much better than a flooded battery, Its CCA is not much if any battery than a flooded starting battery, adn their claims of deep cycling ability is not really impresive at 350 cycles to 50% depth of discharge, where as Odyssey claims something like 800 cycle to 50%, in addition to having 30% more CCA.

AGM batteries as starting batteries are usually of little benefit. They are certainly not the Super battery than their price and consumer mindset usually assign to them.

Most vehicles voltage regulators are way too timid to ever exceed the 'recommended' limitations of an AGM, but a super Hot AGM being fed 14.7v all day long is certainly not a good thing. Not good for the Flooded battery either, but the flooded battery can be watered if low.

The temperature at chich the battery is Kept and how close to 100% charged are the main determinants in tbattery longevity. The absolute best battery chronically undercharged and exposed to hot temperatures will not outlast the cheapest battery kept coller and fully charged.

Any reports of Longevity, good or bad, without knowing how the battery was treated, in terms of how close it was kept to 100% charged, or the average temperature and maximum temperatures to which is was exposed through out its lifespan, are entirely meaningless. Unless of course battery X shorts a cell in a month and many others report the same occurrence.

Beware of assigning any AGM 'super battery' status. Some can indeed be super batteries with super low self discharge and almost obscene CCA and PCA figures and crank and engine violently quickly to life. But if these batteries are accidentally deeply discharged and not recharged properly, or not fully recharged, they will lose that ability, and not really last any longer than the cheapo starting battery with the 2 year free replacement warranty available nationwide.

Buyer beware of marketing, buy buyer must also accept some responsibility on the proper care and feeding to maximize the longevity.

 

[SHOZ]

The last Odyssey I bought was used a PC 925. It had been sitting on a shelf outside for two years and was dead as any battery can get. I do have a charge made for the Absolyte line of hand lift truck batteries. But it took 4 days for the thing to come to life. Still in use today. One of the brands in my Hyundai is a Pilot, not sure of the other.

The sealed and liquid trapped qualities are what I like. No leaky batteries and no more maintenance for hat matter.

 

[slowrench]

Can anyone explain the fact or theory of two batteries same size, same weight,but one has more lead plates to achieve something,i forget. This may have a negative effect on battery life.How can you tell the difference.

 

[Chris142]

Agm is all i will run. My exide orbital lasted 90 months. I replaaced it with an optima red top and i relaced it with a deka intimadator a few weeks ago only because it was going on 7 yrs. Wet batteries never last that long plus they corrode the terminals constantly.