AGM batteries - are they better?

they cost yes..
weight ISSUE and less amphrs exist with 'SPIRAL WOUND' 6 pack batteries like Optima

this is NOT the case when dealing Lifeline , and other premium AGM batteries

i have grp29~31 ? format AGM's that weigh 100# each and are rated at 139 amphrs each

generally AGM's recharge faster in bulk mode, but all batteries take time to get back to 100%

generally AGM's have a 'LOWER' self discharge rate, and IF fully charged will hold charge longer than flooded cell batteries

too many people keep applying, GEL characteristics and faults to AGM, even though it has been stated many times, they ARE NOT the same thing

old guy wrote:
I think the two main reasons they are not used is the cost and the discharge rate they have compared to acid batteries. and recharging that battery back up to full charge after many discharges.

Superior charging speed
Superior vibration resistance
Superior resistance to shorted cell
Superior resistance to freeze damage
Reduced maintenance
Reduced self discharge in storage

Mounted on side seems Ok but inverted is not recommended.
AGM will gas less to none but is not exempt from RVIA standards to vent battery outside the living space.

I expect 400 amp hours of AGM will have the same power as 400 amp hours of flooded. Same group 27 (as example) will have less amp hours.

Must have an appropriate charging system.

And then there is cost.

MEXICOWANDERER wrote:
It is a lot heavier than a flooded battery
It has about 85% of the usable capacity of a flooded battery
Then look at the price.

Thanks. I didn't realize the energy density was lower. I was aware of the price difference. Extra weight for the same capacity is a concern for me. I need to keep my chassis weight down. The list of advantages was compiled by the AGM manufacturer, so clearly they aren't about to tell me the disadvantages.

I'd still like very much to see how fast they charge from 80% SOC to 100% SOC.

pugslyyy wrote:
AGMs are fantastic - but only you can decide whether they are worth the premium to you.

Lifeline is a pretty well regarded and their website is comprehensive - worth a look for even general AGM info.

http://www.lifelinebatteries.com/rv.php

(I have over $2000 of AGMs in my rig)

How many AHs do you have in your bank?

I read the list of advantages. I saw nothing that convinced me, but it left questions open.

The high charge rate is nice, but it looked like it was avoiding the questions I have.

1) I'd have to buy a new charger to gain anything.

2) 500A is well beyond my gen capability, so I couldn't power that anyway.

3) It didn't say I could charge at a higher rate at the tail end of the charge cycle, which is where I run most of the time.

I'd need a charge diagram to see that, and so far I haven't found one. It's no good to me if my last hour of AGM charge is the same as the tapered last hour of my FLA that I currently see. I spend most of the time recharging in that last hour, and I already own a charger that's bigger than the FLA's will accept. It's not of value to me if the entire high charge rate advantage lies in the below 80% SOC charge region. I need better performance in the 80% to 100% region.

Finally, the improved cycle life is also nice, but it's eaten up by the increased cost. I already get 6-8 years of life depending on usage and care. I'm not convinced I'd really get 18-24 years of life, which is what the cycle life implies. My battery life isn't limited by cycle life, but by age of the batteries.

I'm looking for real world advantages in the way I use my batteries. I'm not trying to convince anyone else that AGMs aren't good for them, but so far I don't see advantages for me.

(The decreased discharge rate is also nice, but not something that concerns me. There's no significant discharge during my typical RV trip, and I keep the batteries plugged in and charge maintained when I'm not traveling.)

Here's a good study.

Find an image of an AGM battery online. Stare at it, while pondering the following...

It is a lot heavier than a flooded battery

It has about 85% of the usable capacity of a flooded battery

Then look at the price.

At this point, study the "sealed no maintenance" points, higher CCA and discharge capabilities.

Then return and look at the price.

Sleep on it a week if you have to.

Then look at the price one last time...

Have you fallen off the fence to one side or another, yet?

AGMs are fantastic - but only you can decide whether they are worth the premium to you.

Lifeline is a pretty well regarded and their website is comprehensive - worth a look for even general AGM info.

http://www.lifelinebatteries.com/rv.php

(I have over $2000 of AGMs in my rig)

I think the two main reasons they are not used is the cost and the discharge rate they have compared to acid batteries. and recharging that battery back upto full charge after many discharges.