Are AGM's worth the extra $

[Steve Kiemele]

Originally Posted by wa8yxm

What I have heard and what I have found

AGMs:
- Charge faster
Lifeline does recommend a faster recharge for THEIR AGM's. but that is brand specific, other brands. NOT so

- Don’t self-discharge as fast
In my testing this was never an issue with either AGM or Flooded wet so I can not say.

- Are maintenance free (don’t need watering)
True

- Don’t corrode your battery compartment and cables
Not true. but they do not corrode as fast.. Corrosion happens due to many things. AGM's (And in fact most all Maintenance free types) address ONE of those issues.

Longer overall life.. I found the opposite

Can be mounted at odd angles, no This Side Up... True

WAY HIGHER COST.. True.

Regarding charging,the AGMs accept amps at a higher rate. You don’t do anything to charge faster; the batteries just accept the charge.

Regarding corrosion, I agree that if you spray salt and acid in your battery compartment, you will still have a corrosion problem. If you don’t do that and switch to AGMs, you will have greatly reduced corrosion.

I have not tried to measure self-discharge rates. This feature is just generally accepted.

One thing to keep in mind: AGMs will sulfate just like wet cells if you only recharge them to 80% or so. You need to recharge them to float level ASAP.

[757driver]

Originally Posted by Steve Kiemele

Regarding charging,the AGMs accept amps at a higher rate. You don’t do anything to charge faster; the batteries just accept the charge.

Regarding corrosion, I agree that if you spray salt and acid in your battery compartment, you will still have a corrosion problem. If you don’t do that and switch to AGMs, you will have greatly reduced corrosion.

I have not tried to measure self-discharge rates. This feature is just generally accepted.

One thing to keep in mind: AGMs will sulfate just like wet cells if you only recharge them to 80% or so. You need to recharge them to float level ASAP.

Actually you do/should consider charge rate when charging batteries, depending on the type. On most if not all inverter/chargers there is a setting for charge rate expressed as a percentage of the chargers overall output. Most flooded batteries should be charged at 10-15% of their “C” rating. AGM batteries can take 25% or higher. On a 400 AH flooded battery bank and a 100 AH charger the charge rate should be dialed back to 40-60%. On a 400 AH AGM battery bank that charge rate could be set to 100%. Both will accept the high rate of charge (as you mentioned) but for one it is good for the other it is harmful.

[Winemaker2]

Be careful accepting the "AGMs charge faster" statements w/o understanding all the specifics.
Heres the best article / tests I've seen that expose some of the myths.
https://marinehowto.com/how-fast-can...ry-be-charged/

My take is they CAN be charged faster but it may take a change snd possibly an investment in charge equip to get it.

Self discharge rate is attractive vs FLA.
I disconnect 4 AGM battys on our boat during off season storage and measure V before reconnecting each spring.
For last 5 yrs my AGMs read 12.6-12.7 V after sitting from mid Sept to end of Apr.
I do make sure they are fully charged in the fall before disconnecting.
No data but doubt FLA could do that.

[l1v3fr33ord1]

I have a 2 x 6V coach, so a smaller dog in this fight than many.

For it and the former coach, both needing battery replacement upon purchase, I chose AGMs. I obsess about so many things that it's nice to have a product I can install and ignore.

I bought Lifelines in both cases. They have a great reputation. Not dissing the other high-end makers, though.

As I said, I'm the chihuahua among a bunch of danes and mastiffs.

I note that for some folks, safely accessing the batteries for water level checks is difficult enough to compel using a watering system.

[757driver]

Originally Posted by Winemaker2

Be careful accepting the "AGMs charge faster" statements w/o understanding all the specifics.
Heres the best article / tests I've seen that expose some of the myths.
https://marinehowto.com/how-fast-can...ry-be-charged/

My take is they CAN be charged faster but it may take a change snd possibly an investment in charge equip to get it.

Self discharge rate is attractive vs FLA.
I disconnect 4 AGM battys on our boat during off season storage and measure V before reconnecting each spring.
For last 5 yrs my AGMs read 12.6-12.7 V after sitting from mid Sept to end of Apr.
I do make sure they are fully charged in the fall before disconnecting.
No data but doubt FLA could do that.

Some interesting reading there Don, thanks for posting.

[Winemaker2]

Originally Posted by 757driver

Some interesting reading there Don, thanks for posting.

That Marine How To site has some very well done articles that apply to RVs as well as boats
Deep Cycle Battys
DIY Batty Cables
Wire terminals... etc

https://marinehowto.com/

[ALLOY]

Filling FLA is a pain but I've found being able to check the specific gravity is a plus.

A less expensive option to AGM are Sealed VR batteries...

[Scottybdivin]

Originally Posted by ALLOY

Filling FLA is a pain but I've found being able to check the specific gravity is a plus.

A less expensive option to AGM are Sealed VR batteries...

I can fill my 8 T-105's in about 5 min. 4 min to dig out the pump and jug of water and 1 min to complete the fill on all 8.

[757driver]

Originally Posted by Winemaker2

That Marine How To site has some very well done articles that apply to RVs as well as boats
Deep Cycle Battys
DIY Batty Cables
Wire terminals... etc

https://marinehowto.com/

I have been to that site before, many informative articles. I especially liked the write up on LiFePO4 batteries.

[Winemaker2]

Originally Posted by ALLOY

Filling FLA is a pain but I've found being able to check the specific gravity is a plus.

A less expensive option to AGM are Sealed VR batteries...

I thought AGMs were sealed valce regulated?
I'll look but wonder if you can post a link to one.

[Nasdaqsam]

Great discussion and feed back. Thank you for the education for sure. I went to Sam's to pick up the AGM's. Web sight says 10 in stock I get there to find 2. No more until the next truck in 10 days. I start looking at the Regular golf cart batteries and thinking do I really need the AGM's that bad? As I stand the guy next to me says you scouting them out and waiting for the sale tomorrow too? Huh.......ahhhhh did you say sale? One day only $20 off in stock batteries only. At $79 less $20.....$59 is a tough deal to beat. I would have gotten the AGM's tomorrow if the had them.

[lajuene]

T-105 6v $155 = 230AH, useable 115AH

X6 batteries = $930 = usable 345AH

$930/345AH usable = $2.69/AH

--------------------

AGM 6v $389x2=220AH=110AH useable

X6 batteries = $2334 = usable 330AH

$2334/330AH usable = $7.07/AH

--------------------

Lithium 12v $950 100AH useable 80AH

X4 batteries = $3800 = useable 320AH

$3800/320AH useable = $11.80/AH

--------------------

Then you need to wiegh the benefits of each type and decide which is best for what you want and are willing to pay.

--------------------

We had all 3 types. AGM was a great upgrade and then they wore our lithium was a great upgrade. We really LOVE lithium because of being able to draw down to almost zero, extrwamly fast recharge in bulk mode all the way to 100%, way less weight. Longer life with many more charge cycles. Expensive though. Added them to our insurance policy by calling and making sure they had proof we installed them.

[staggerlee]

I bought 3 AGM Trojan batteries for the house. I got around 100.00 ea. off because they were factory blems, with same warranty.

When I change the start batteries it will be the group 31 "Overdrive" Trojans.
I will be going back to the same dealer, hoping I can get blems too.

[Searching_Ut]

I personally don't find AGM to be worth the price difference if the choice is between the two lead acid variants. I've been involved in testing and servicing batteries of all types over the years. When properly maintained, all the real world results I've seen give flooded cells about a 12 percent lifetime power output advantage over AGMs when comparing comparable batteries. That said, depending on how you intend to abuse, and maintain your batteries as well as the constraints of your battery location could easily make AGMs a better choice.


My batteries are easy to get at for servicing, and I have my charging system set up to where outgassing isn't a significant issue so my annual battery maintenance is only 30 or so minutes a year, with much of that being checking the connections for security. If I spend a lot of time on shore power instead of solar, and my somewhat crude Progessive Dynamics PD 9280 converter/charger isn't switched off my battery servicing needs go up to every couple months that the charger is running. You kind of have to learn what your system norms in determining how often to do your servicing.