AGM battery life?

[Brewbud]

A lot depends on the manufacturer. I went through 3 Red Top Optima AGMs in my jeep in 4 years. Switched to a Diehard Platinum+ (Rebranded Odyssey) and it is still going strong after at least 4 years. My Cummins goes through dual flooded batteries every 2-3 years. I think it is the grid heater that really takes those down.

 

[Flipper]

This AGM mystique is out of control. I have been reading all the posts and threads on AGM, and lots of “expert “ opinions and comments are just flat wrong, overcharging, undercharging, incorrect application, one post suggested reserve capacity was a smaller battery inside the battery. A lead acid battery is a plastic box filled with LIQUID acid, and AGM is nothing more than the same plastic box , they just soak the liquid acid in fiberglass cloth ( the acid does not destroy the fiberglass cloth) and seal the box. So they have the two dissimilar metals sandwiched in between the cloth instead of sloshing around in a tub of liquid acid.. In an Optima battery they just roll them up like a fruit cake instead of sandwiching them flat, basically a gimmick. The great thing about AGMs there is nothing to leak, or vent gas so you can use them in an enclosed compartment, you can even lay them on their sides. They have been used in aircraft for years because of this.
Here is the biggest misconception. There a basically 3 types of batteries, AGM or lead acid. A Start, dual purpose and deep cycle. A start battery has multiple thin plates that gives a large current draw for a short time. That’s why it goes dead if your truck won’t start after several tries. A deep cycle battery has really thick plates for a LOW CONTINUOUS DRAW, NOT CRANKING A STARTER! A dual purpose battery has medium size plates so it can handle a low continuous draw or a large current burst......hence the name Dual Purpose.
If you use a start battery, AGM or Lead Acid, in a deep cycle application you will drastically reduce the life of the battery.
If you use a deep cycle battery, AGM or Lead Acid, in a start application you will drastically reduce the life of the battery. Another issue AGMs are very sensitive to OVERCHARGING, 14.6-14.8 for a deep cycle charge 13.6-13.8 standby use. So the DC to DC chargers that are pumping 15 +volts are damaging the batteries.
Use the correct battery for the correct application.

 

[Brewbud]

This AGM mystique is out of control. I have been reading all the posts and threads on AGM, and lots of “expert “ opinions and comments are just flat wrong, overcharging, undercharging, incorrect application, one post suggested reserve capacity was a smaller battery inside the battery. A lead acid battery is a plastic box filled with LIQUID acid, and AGM is nothing more than the same plastic box , they just soak the liquid acid in fiberglass cloth ( the acid does not destroy the fiberglass cloth) and seal the box. So they have the two dissimilar metals sandwiched in between the cloth instead of sloshing around in a tub of liquid acid.. In an Optima battery they just roll them up like a fruit cake instead of sandwiching them flat, basically a gimmick. The great thing about AGMs there is nothing to leak, or vent gas so you can use them in an enclosed compartment, you can even lay them on their sides. They have been used in aircraft for years because of this.
Here is the biggest misconception. There a basically 3 types of batteries, AGM or lead acid. A Start, dual purpose and deep cycle. A start battery has multiple thin plates that gives a large current draw for a short time. That’s why it goes dead if your truck won’t start after several tries. A deep cycle battery has really thick plates for a LOW CONTINUOUS DRAW, NOT CRANKING A STARTER! A dual purpose battery has medium size plates so it can handle a low continuous draw or a large current burst......hence the name Dual Purpose.
If you use a start battery, AGM or Lead Acid, in a deep cycle application you will drastically reduce the life of the battery.
If you use a deep cycle battery, AGM or Lead Acid, in a start application you will drastically reduce the life of the battery. Another issue AGMs are very sensitive to OVERCHARGING, 14.6-14.8 for a deep cycle charge 13.6-13.8 standby use. So the DC to DC chargers that are pumping 15 +volts are damaging the batteries.
Use the correct battery for the correct application.

All great info, however, simply adding the glass mat to the cell does change the characteristics of the battery. AGM batteries typically have lower internal resistance and are less prone to sulfation. They also have a low self-discharge. This means they can sit in storage for longer before a charge becomes necessary. This is important for me as my Jeep is not a daily driver.

 

[Flipper]

All great info, however, simply adding the glass mat to the cell does change the characteristics of the battery. AGM batteries typically have lower internal resistance and are less prone to sulfation. They also have a low self-discharge. This means they can sit in storage for longer before a charge becomes necessary. This is important for me as my Jeep is not a daily driver.

Agreed, I just tried to keep it to the basics. Same with our 2 group 31 house batteries, they sit for weeks on end until our next adventure. I float mine at 13.8v. Being as expensive as they are I want them to last as long a possible. The Optima, deep cycle in my skiff, used for deep cycle only application was bought in 2007 and is still good!

 

[Viking1204]

This AGM mystique is out of control. I have been reading all the posts and threads on AGM, and lots of “expert “ opinions and comments are just flat wrong, overcharging, undercharging, incorrect application, one post suggested reserve capacity was a smaller battery inside the battery. A lead acid battery is a plastic box filled with LIQUID acid, and AGM is nothing more than the same plastic box , they just soak the liquid acid in fiberglass cloth ( the acid does not destroy the fiberglass cloth) and seal the box. So they have the two dissimilar metals sandwiched in between the cloth instead of sloshing around in a tub of liquid acid.. In an Optima battery they just roll them up like a fruit cake instead of sandwiching them flat, basically a gimmick. The great thing about AGMs there is nothing to leak, or vent gas so you can use them in an enclosed compartment, you can even lay them on their sides. They have been used in aircraft for years because of this.
Here is the biggest misconception. There a basically 3 types of batteries, AGM or lead acid. A Start, dual purpose and deep cycle. A start battery has multiple thin plates that gives a large current draw for a short time. That’s why it goes dead if your truck won’t start after several tries. A deep cycle battery has really thick plates for a LOW CONTINUOUS DRAW, NOT CRANKING A STARTER! A dual purpose battery has medium size plates so it can handle a low continuous draw or a large current burst......hence the name Dual Purpose.
If you use a start battery, AGM or Lead Acid, in a deep cycle application you will drastically reduce the life of the battery.
If you use a deep cycle battery, AGM or Lead Acid, in a start application you will drastically reduce the life of the battery. Another issue AGMs are very sensitive to OVERCHARGING, 14.6-14.8 for a deep cycle charge 13.6-13.8 standby use. So the DC to DC chargers that are pumping 15 +volts are damaging the batteries.
Use the correct battery for the correct application.

In the Marine industry they make batteries labeled Starting/Deep Cycle and I have found those work the best for Overland applications and I put those in my truck too. The reason for this is they still have plenty of cranking power but also have a high ah rating allowing you to run low amperage items off them for a short time and still start your vehicle. I don't think there is any AGM mystique, the fact is AGM batteries in general have proven they last longer than a standard lead/acid battery and they are marketed as such. AGM batteries built for large UPS units have a 10 year life expectancy, I found this out when I acquired a few of them. Now I use one 90ah UPS battery and can power my fridge for 48 hours with it. Once I attach solar to it I have no doubt I'll be able to run my fridge for several days. My starting battery in my truck has 925 cranking amps and 90ah so it serves as my backup should I need to run my fridge off it. Came in handy the other day when we were out shopping and bought some tuna and shrimp dip at a farmer's market, just plugged the fridge in to the cigarette lighter plug in the back seat and it kept the dip cold while we shopped around some more. At the time I didn't have my UPS battery with me, it was at home charging.