AGM vs. Flooded

garageman402

garageman402

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This seems to be an on-going debate, but seriously, what is the advantage to an AGM over a flooded? This is going in the 2008 Enclave, which has the battery in the floor behind the passenger seat. It has a tube to vent to the outside, the Delco 48PG that is specified for this is not AGM I believe. It's solidly mounted, I presume in a roll-over, the electrolyte would flow (if it did escape) out that vent tube. Heat is not an issue being away from the engine.

NAPA uses East Penn, which I like, and the price difference is $30. Right now they are offering $20 off of a $75+ purchase, and my battery has been in for 3 years now, so I'm looking. If I'm reading their ad correctly, the AGM has a 24 month warranty, where the AAA flooded battery supposedly has a 36 month warranty, but when you click on it, the NAPA battery pops up with 24 month warranty.

It seems that battery manufacturers have gone away from any kind of pro-rated warranty, I think as of 4/2020. Haven't been to Costco for batteries since before Covid, so not sure of their policy now.

So what is the advantage to AGM? They can cycle more deeply? Last longer (in spite of shorter warranty period)?
 
bullwinkle said:
I personally like East Penn flooded, although in a high vibration/off road/racing situation an AGM would probably last longer. I just haven’t seen the ROI on a twice as expensive AGM.
Click to expand...
Ya middle of the wheelbase mounting location, vibration shouldn't be an issue
 
My car came with agm I dont have to decide.. it gets an agm. No doubt they are superior.. but if it matters in your application is unknown.

garageman402 said:
NAPA uses East Penn, which I like, and the price difference is $30. Right now they are offering $20 off of a $75+ purchase, and my battery has been in for 3 years now, so I'm looking. If I'm reading their ad correctly, the AGM has a 24 month warranty, where the AAA flooded battery supposedly has a 36 month warranty, but when you click on it, the NAPA battery pops up with 24 month warranty.
Click to expand...
For me the napa legend premium agm is 18month replacement 75? month pro rated.. their warranties are hard to find.

I picked up mine for $128 in h7 AGM size (also group size 94r)
 
Last edited:
AGM batteries don't really last longer, the main advantage is they won't leak acid and don't have to be mounted upright. As long as remember to connect the tube you won't have to worry about battery acid corroding the tray.
 
garageman402 said:
This seems to be an on-going debate, but seriously, what is the advantage to an AGM over a flooded? This is going in the 2008 Enclave, which has the battery in the floor behind the passenger seat. It has a tube to vent to the outside, the Delco 48PG that is specified for this is not AGM I believe. It's solidly mounted, I presume in a roll-over, the electrolyte would flow (if it did escape) out that vent tube. Heat is not an issue being away from the engine.

NAPA uses East Penn, which I like, and the price difference is $30. Right now they are offering $20 off of a $75+ purchase, and my battery has been in for 3 years now, so I'm looking. If I'm reading their ad correctly, the AGM has a 24 month warranty, where the AAA flooded battery supposedly has a 36 month warranty, but when you click on it, the NAPA battery pops up with 24 month warranty.

It seems that battery manufacturers have gone away from any kind of pro-rated warranty, I think as of 4/2020. Haven't been to Costco for batteries since before Covid, so not sure of their policy now.

So what is the advantage to AGM? They can cycle more deeply? Last longer (in spite of shorter warranty period)?
Click to expand...
Advantage is you won't have battery acid in your floor board.
 
Rand said:
For me the napa legend premium agm is 18month replacement 75? month pro rated.. their warranties are hard to find.

I picked up mine for $128 in h7 AGM size (also group size 94r)
Click to expand...
When was this?

I think it used to be the NAPA part number incorporated the warranty period, e.g. a #7524 was a 75 month Group 24. Now I think they only have the free replacement period.

Now it's $199.99 for AGM Part #9848, & $169.99 for Part #8448 "AAA Battery BCI No. 48 730 A Wet"
 
garageman402 said:
When was this?

I think it used to be the NAPA part number incorporated the warranty period, e.g. a #7524 was a 75 month Group 24. Now I think they only have the free replacement period.

Now it's $199.99 for AGM Part #9848, & $169.99 for Part #8448 "AAA Battery BCI No. 48 730 A Wet"
Click to expand...
last saturday after black friday.
 
the cherokee will actually fit a 27f? which is massive for this size vehicle.. but you have to file the a holddown tab off on the battery it interferes with the clamp.
it was the 30% off napa BF sale.. and of course you get 5$/100 rewards.. and 5% back for paypal with chase freedom CC.

next best price was sams club at 186.99 + tax
or amazon ac delco agm that got bad reviews for around $160
 
Chris142 said:
In the past my AGM batteries have lasted 3x as long as my flooded ones. Got 9 years out of an AGM but barely 3 out of a flooded. Plus the AGM does not corrode the cables like a flooded will.
Click to expand...

A regular flooded lead acid battery won't corrode anything as long as you connect the vent tube.
 
Rand said:
the cherokee will actually fit a 27f? which is massive for this size vehicle.. but you have to file the a holddown tab off on the battery it interferes with the clamp.
it was the 30% off napa BF sale.. and of course you get 5$/100 rewards.. and 5% back for paypal with chase freedom CC.

next best price was sams club at 186.99 + tax
or amazon ac delco agm that got bad reviews for around $160
Click to expand...
Ya Amazon sells old date codes
 
generic internet also offers this nugget of questionable agm info

Advantages of the AGM battery​


What are the advantages of the AGM battery?
AGM batteries have a very low internal resistance, are capable to deliver high currents on demand and offer relative long service life, even when deep-cycled.
AGM is maintenance free, provides good electrical reliability and is lighter than the flooded lead-acid type.
It stands up well to low temperatures and has a low self-discharge.
The leading advantages are a charge that is up to five times faster than the flooded version,
and the ability to deep cycle. AGM offers a depth-of-discharge of 80 percent; the flooded,
on the other hand, is specified at 50 percent DoD to attain the same cycle life.
Click to expand...
 
So The AGM has higher CCA but lower CA than the flooded. I have been in 0° weather exactly 0 times. I’m more likely to experience 32° weather which the CA is based on.

Speaking of that, at what temperature does battery electrolyte freeze? I’ve read where a previously frozen battery will not be warrantied, how do they test it a 0°?
 
Rand said:
generic internet also offers this nugget of questionable agm info
Click to expand...
Thanks for posting that, I do question that info:

If the internal resistance is so low then why is the 32° CA rating higher in a flooded battery than an AGM?

I put flooded batteries in my RV (house battery) because they were rated for deep cycle, and fast charging would be a minor issue in my opinion.
 
Jake_J said:
AGM batteries don't really last longer, the main advantage is they won't leak acid and don't have to be mounted upright. As long as remember to connect the tube you won't have to worry about battery acid corroding the tray.
Click to expand...
They do often last longer, but that’s because their self discharge is lower, they recombine hydrogen and oxygen faster, and they don’t shed plate materials as easily.
 
add to that, the plates in agm’s are mechanically braced by the mat. So they can’t deform and contact each other causing cell shorting from wear or vibration. It’s a mechanically more durable design. The only BUT to that, is that the same mechanical design makes them less tolerant of overcharging. my agm experience is that they probably will last longer. since I’ve swapped over I haven’t had one fail yet (except one knowing purchased after sitting on the shelf for 7 months, which then failed under warranty) so I don’t really know how much longer. I think our oldest agm is now 8 years old, in a trunk-mounted Volvo.
 
AGM's bulk charge faster than flooded due to low resistance. Some can take ~500A bulk charging ... if you have the dual alternators to feed it all it can take. Leave your lights on too long and then start the engine: the charge current can toast the 1990's GM firecracker alternators. The faster charging in short trip use can allow the AGM to last longer.

"Spill Proof" is NOT "Leak Proof"! Yes the battery cables generally last longer. However when the terminal seal cracks they can leak just like a"Dry Cell" flashlight battery and corrode the cable and battery pan. It's not a given the cables will corrode like flooded batteries are well known to do.

Vibration from our bad roads to air cooled single cylinder Diesel light plants that shake the bolts out of everything: hands down AGM wins.

Lower self discharge is irrelevant in most cases when the vehicle is left parked for weeks. The onboard computers will suck the battery dry no matter what kind it is. If you pull that cable off or the "Storage" fuse some vehicles have: then it can make a difference.

AGM's have a past reputation for lasting longer. Nothing you can bank on. Heat kills batteries and the extreme heat here means you replace the battery at 2 years if it made it that long. Or you take your chances of when it will fail in year 3.

BattriesPlus does offer an in house extended warranty of 5 years total on some of their AGM batteries: like the X2 and Odyssey.

In depth info on AGM look at the Lifeline Technical Manual

lifelinebatteries.com

Knowledge Center - Lifeline Batteries

If you cannot find what you are looking for below, we are standing by to help you with your battery needs. Feel free to contact us anytime and talk to a real
lifelinebatteries.com lifelinebatteries.com
 
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