Log In | Register
Skip to main content
Topic: Expected agm battery life? (Read 989 times) previous topic - next topic
0 Members and 2 Guests are viewing this topic.
Expected agm battery life?
As I enter the 7th season of my 2011 24FL, I'm starting to wonder just how long I should trust my original equipment AGM coach batteries. Thoughts?

I've run into several other 2011s and they had to replace theirs years back.

I average 100 days a year in it, mostly on shore power, but I also dry camp several times a year.

Original converter & 200 watts LD installed solar. No problems.

...am I being a nervous nellie or pushing for too much...or what.

Thoughts? Again, these are the factory installed AGMs. (Original chassis battery too.)

Lori Y
2011 24FL
Lori Y
2011 24FL

Re: Expected agm battery life?
Reply #1
Expected battery life depends on many factors.  There is no simple answer to your question.    Good upkeep and use can get a set of AGM's to 10 or more years.   Too many variables for anyone to make a hard and fast rule.   RV use generally is very hard of batteries as most of us treat the house batteries like we treat our car batteries.    Enclosed is a Lifetime Tech Manuel.
Lifetime  Tech Manual

A quick method to check you batteries.    Fully charge them  ie run the generator for a few hours or drive a  long distance.   Assuming a full charge -  disconnect the batteries.  Let them rest for at least 24 hours.   Then measure voltage.    This will tell you the condition of the battery.    The above manual will cover this in more detail. 
personal fine art photo stuff
TF Mack | Flickr
It's all good .......
2014 Twin King

Re: Expected agm battery life?
Reply #2
Can someone check today's battery logic:

A few days ago, my generator wouldn't start. Cranked to a count of 10 after priming, cranked weaker 2d time & barely cranked 3d time...just like weak batteries. Idiot lites said full charge, as they should have, since it had been plugged in before I disconnected for gen run.

Scratched my head, plugged it in again & left it for a few days before I got back to it.

Today, I left it plugged in and the generator fired right up. (I know my system defaults to the generator when it's running)

My logic says: Batteries charging, but not holding the charge under load. Ergo, time for new batteries.

Does that track?

Lori Y
2011 24FL



Lori Y
2011 24FL

Re: Expected agm battery life?
Reply #3
Lori from how you explained it. It sure sounds like it's new battery time. A lot of battery retailers have load testers and can check your batteries condition. Myself I am a better safe than sorry guy. So with the age of the batteries and the problems you noted. I would probably be replacing them.
Lynn and Lori

Re: Expected agm battery life?
Reply #4
"A few days ago, my generator wouldn't start. Cranked to a count of 10 after priming, cranked weaker 2d time & barely cranked 3d time..."

The battery issue aside... next time the gen is reluctant to start, fire up your truck engine! This will give the gen set the little kick in the butt that it needs to start. Been there, done that!   :)
Steve S.
Lazy Bones & Cedar
2004 30'IB (Island Bed)
Yesterday is History, Tomorrow is a Mystery
Live for the day!

 

Re: Expected agm battery life?
Reply #6
IMO, this website is the most accurate, reliable, comprehensive, and frequently updated source of battery information:

Car and Deep Cycle Battery FAQ 2017, Battery Manufacturers and Brand Names...

As ever, YMMV.

This is a very good site but it only covers lead acid batteries.  The OP was asking about AGM's.  
personal fine art photo stuff
TF Mack | Flickr
It's all good .......
2014 Twin King

Re: Expected agm battery life?
Reply #7
"This is a very good site but it only covers lead acid batteries. The OP was asking about AGM's."

AGMs are lead-acid batteries, and at least some of the material on that site (e.g. the Excel spreadsheet) specifically mentions AGMs.
Andy Baird
2021 Ford Ranger towing 2019 Airstream 19CB
Previously: 1985 LD Twin/King "Gertie"; 2003 LD Midbath "Skylark"

Re: Expected agm battery life?
Reply #8
More battery sites that describe the differences among AGM, gel, and flooded lead acid batteries:

Absorbent Glass Mat (AGM) Battery Information - Battery University

Knowledge Center - Lifeline Batteries

VRLA battery - Wikipedia

I believe that many RVers may choose AGM batteries despite the considerably increased cost over flooded cell lead acid batteries because they have been told that AGMs are  "maintenance free". While it's true that one doesn't add water to the electrolyte in the cells of  AGMs, they do require "maintenance" in the form of checking the connections, cleaning the terminals, and making sure that all the components, i.e., batteries, charge controller, and multi-stage converter are matched and playing together nicely.

Advantages and disadvantages of AGMs are described in a chart in the first linked site above; in addition to their high cost, the main disadvantage of AGMs (IMO) is that they are very sensitive to overcharging, and will fail prematurely if an "inadequate" charge controller allows repeated overcharging.

A few years ago when AGMs began to become popular replacements for "traditional" flooded cell batteries (e.g., replacing Trojan T105s in many LDs), understanding of the technology and specific requirements of AGMs could be a little sketchy; even some respected installers (apparently) didn't fully realize the need to match capabilities among the batteries, charger, and converter, and expected the AGMs to function with whatever controller and converter was in the rig . The HPV-22B, a fairly advanced charge controller in its time, consistently allowed overcharging of the first set of AGMs in my 2003, to the point that one of the batteries split around the terminal; the failure happened about 4 years from the time the AGMs were installed. (The converter at the time was the original Parallax 7300).

Battery and associated component technology (like most other technology!) develops very rapidly; before spending about $600 on a pair of AGMs, I suggest making sure that one understands the advantages and disadvantages of this battery type and ascertaining whether the solar controller and converter in the RV are of like technological capabilities and are matched with the AGMs.

P.S. Trojan T-105s (or the T-125s, T-145s, if they will fit) and a Pro-Fill (or similar) battery watering system are excellent choices for many LDers!  ;)

As ever, YMMV.



2003 TK has a new home

Re: Expected agm battery life?
Reply #9
Lori from how you explained it. It sure sounds like it's new battery time. A lot of battery retailers have load testers and can check your batteries condition. Myself I am a better safe than sorry guy. So with the age of the batteries and the problems you noted. I would probably be replacing them.
Unfortunately, most battery dealers do not have a large enough battery tester to adequately test deep cycle batteries.
The load bank I used, when employed, was big enough to be mounted on a trailer.
This is a situation where a battery capacity meter is very useful.

In normal usage, RV batteries last 5-7 years, with a occasional sets reaching 10 years.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze

Re: Expected agm battery life?
Reply #10
As noted above, different folks will have different experience.  This is mine.  In November, 2008, I had my two factory batteries, stored outside, removed and had 6 AGM's installed under the front dinette seat in my mid bath.  I have been fulltiming all that time.  in warm weather I do a lot of dry camping, plus I use a computer for several hours a day, a DVR, a TV for several hours every evening and a CPAP machine all night.  On a typical summer day, I will start battery usage with a 100% charge around 5 PM.  By the next morning I am in the mid-70's % if I leave the DVR plugged in overnight, and low 80's % if I unplug the DVR by 10 PM.  If I have a very good location for my 5 AM100 solar panels, my battery bank is back to 100% by mid- to late afternoon.  If not so good, I run my generator for an hour in the morning.  In winter months, I am usually plugged into shore power.  It is the original battery pack, now 8 1/2 years old, and the batteries are not showing any significant departure from those numbers in all these years.  This may be significant - the batteries are inside, so are kept at a constant room temperature year round.

Ken F  in NM
'08 MB

Re: Expected agm battery life?
Reply #11
Ken, which charge controller and converter do you have?
2003 TK has a new home

Re: Expected agm battery life?
Reply #12
Joan, I have a Magnum 2000 watt whole house inverter and controller.

Ken F in NM
'08 MB

Re: Expected agm battery life?
Reply #13
Well, OK, that should do it!  :D  Thanks, Ken!
2003 TK has a new home

Re: Expected agm battery life?
Reply #14
As noted above, different folks will have different experience.  This is mine.  In November, 2008, I had my two factory batteries, stored outside, removed and had 6 AGM's installed under the front dinette seat in my mid bath.  I have been fulltiming all that time.  in warm weather I do a lot of dry camping, plus I use a computer for several hours a day, a DVR, a TV for several hours every evening and a CPAP machine all night.  On a typical summer day, I will start battery usage with a 100% charge around 5 PM.  By the next morning I am in the mid-70's % if I leave the DVR plugged in overnight, and low 80's % if I unplug the DVR by 10 PM.  If I have a very good location for my 5 AM100 solar panels, my battery bank is back to 100% by mid- to late afternoon.  If not so good, I run my generator for an hour in the morning.  In winter months, I am usually plugged into shore power.  It is the original battery pack, now 8 1/2 years old, and the batteries are not showing any significant departure from those numbers in all these years.  This may be significant - the batteries are inside, so are kept at a constant room temperature year round.

Ken F  in NM

Ken, that's impressive.  I have a similar set up to you, including similar panels (I have 2x RV-100 and 2x RV-150).  I also have a Magnum ME-RC50 inverter and charger.  I have 2x GPL-6C AGM Lifeline batteries in the original battery compartment, and 2x GPL-4C AGMs under the Fridge in my 2000 MB.  I'm guessing we both got them from AM Solar (mine in June 2008).

Can I ask you what you look at besides level of charge to know how your batteries are doing?  I have the Magnum display and a Xantrex Battery Monitor.

Thanks -- and I'll be curious to know when your batteries show a notable loss of performance.

S-
Steven & Carol Crisp -- 2000 26.5' Blue Mid-Bath named Thistle Dew Too
Our RV Motto:  "No place to be ... and all day to get there"
2024 Adventure: The Great Eclipse Escapade!  HI(Air),NV,AZ,NM,Mason,TX(Totality!) ...

Re: Expected agm battery life?
Reply #15
Steve, it sounds like you have two batteries inside and two outside.  Be aware that batteries at different temperatures have different charge and discharge rates.  Also, two are 220 Ah and 2 are 300 Ah.  That might also be a concern, but if AM Solar set it up, it is probably ok.  They did mine in November, 2008.  Mine are all GPL-4C's and are all inside.

I monitor my battery condition by checking their level of charge in the morning.  My demand is fairly constant.  If I began to see significantly lower charge levels in the morning, or if I began to see any sign of corrosion on the battery terminals, that would be a reason to be concerned.  So far, I am not there yet.

Ken F in NM
'08 MB

Re: Expected agm battery life?
Reply #16
"I have a Magnum 2000 watt whole house inverter and controller."

Ken, I thought the Magnum 2000 was an inverter/charger.  Does yours also act as a solar charge controller, or is that handled by a separate device such as a Blue Sky controller?
Andy Baird
2021 Ford Ranger towing 2019 Airstream 19CB
Previously: 1985 LD Twin/King "Gertie"; 2003 LD Midbath "Skylark"

Re: Expected agm battery life?
Reply #17
Andy, I have the Hpv-30DR charge controller for the solar side of things.  Sorry about the omission.

Ken F in NM
'08 MB

Re: Expected agm battery life?
Reply #18
The HPV-30DR was one of the Heliotrope family of products; I knew that the company was long gone (the domain name is for sale), but thought that some might find this information (quoted from AM Solar's website) interesting:

"Greg worked with Heliotrope General to design the world’s first dual battery solar charger, the RV30.  As orders were coming in, a fire destroyed the factory where the charge controllers were being manufactured.  Instead of rebuilding, the owner sold the charge controller manufacturing rights to Greg as a percentage of gross sales, thus starting Heliotrope PV.  These charge controllers were initially assembled by hand and later outsourced to electrical assembly factories.  RV manufacturers were the primary market for the controllers, who without solar, were seeing batteries die while their vehicles waited in assembly line parking lots. 

Over time, the expensive analog technology used in the Heliotrope controllers gave way to more efficient digital technology and Heliotrope PV was abandoned...."
2003 TK has a new home

Re: Expected agm battery life?
Reply #19
"I have the Hpv-30DR charge controller"

A word to the wise: keep a close watch on its charging voltages. A few years ago my HPV-30D went haywire and started putting out 16-18V, which quickly destroyed a very expensive set of Lifeline AGM batteries. Of course Heliotrope (literally, "turns to the sun") was long gone by then, so there was no help from that quarter.
Andy Baird
2021 Ford Ranger towing 2019 Airstream 19CB
Previously: 1985 LD Twin/King "Gertie"; 2003 LD Midbath "Skylark"

Re: Expected agm battery life?
Reply #20
"...if I began to see any sign of corrosion on the battery terminals, that would be a reason to be concerned..." (Ken)

So AGM battery terminal corrosion is a sign of failing batteries?

If so, I've been cleaning off and treating the terminals for at least 2 years now. (Being used to standard flooded batteries, I just thought that was normal after a few years.)

Lori Y

Lori Y
2011 24FL

Re: Expected agm battery life?
Reply #21
After the above, I decided to replace my battery bank proactively.  I spoke with the folks at AM Solar.  They said the first indication of AGM batteries coming to the end of their service life would be if they delivered a low voltage under heavy demand.  The specific example mentioned was if I used the microwave through my inverter, and the inverter reported low voltage.  As the AGM batteries are pretty much sealed, I would not expect to see corrosion.  I did not mean to imply that corrosion is a sign to be watching for.  Rather, while I would not expect corrosion in a failing AGM battery, if I saw such, that would be alarming to me.

Ken F in NM
'08 MB

Re: Expected agm battery life?
Reply #22
I did think it was odd for the terminals to corrode. Thanks for the quick answer--I won't panic replace based on that as a symptom of failure.

Can any of you wizards out there explain why AGM battery terminals corrode? (I am in the Seattle area where everything rusts or molds.)

Lori Y
2011 24FL
Lori Y
2011 24FL

Re: Expected agm battery life?
Reply #23
Lori,
It is galvanic corrosion.  The lead, steel and copper create a battery cell in the humid air and corrode just like a copper and steel water pipes do if installed without a dielectric union. 
To prevent the corrosion, i clean every thing with baking soda and water.  The baking soda neutralizes the acid on the surface of the battery.  Don't get baking soda in the battery cell it will neutralize the battery acid and destroy the battery.   Then coat all of the battery connection parts wire lugs, washers and nuts thoroughly with wheel bearing grease.  Assemble, tighten and cover exposed parts with grease again.
When the grease gets thin, do it again.

Like here
http://www.lazydazeowners.com/index.php?action=dlattach;topic=29841.0;attach=2436

This is an old mechanics and AT&T telephone battery bank trick, before the spray on battery stuff.  I have been doing this for 40 years and have had less than 5 battery start failures due to corroded terminals.

P.S.  The AT&T Battery bank used Copper Buss Bars with Brass Screws.  They assembled the joints with Vaseline, petroleum Jelly as described above.
Rodney
1988 Mid Bath

Re: Expected agm battery life?
Reply #24
Lori, if your AGMs are Lifelines, their manual offers comprehensive information on the batteries. According to the literature, the posts of the deep cycle batteries for coach (not engine) use are a copper alloy; the "press" states that this material is superior to lead in resisting corrosion. 

http://lifelinebatteries.com/wp-content/uploads/2015/12/manual.pdf

I never experienced any corrosion on the posts of the first set of Lifeline AGMs, but one did develop a split around the post due to overcharging from an inadequate ("unmatched") charge controller. No issues with the second set of Lifelines (and Blue Sky 3000i).
2003 TK has a new home