Upgrade to an AGM battery. You can safely mount them inside, and upside down, and they will out-perform any flooded battery you ever owned!Here's a quote from another thread. It's typical of others I've seen. I wonder if anyone here can convince me it's correct. Clearly the AGM has some advantages. Two are seen in that quote - inside and upside down. If you need to mount upside down and can't ventilate, sure, that's an advantage, but I don't need those advantages and don't want to pay extra for something I don't need.We're left with the rapid charge rate they are reputed to permit. I would love to run my 80A charger at 80A continuously until I reach 100% SOC. Right now my 460AH FLA batteries recharge at 80A from 50% SOC for about 3 hours (some fluctuation in current - slow climb from below 80 to above 80 during the first hour as they warm up then down to 70+ at the third hour), then begin to taper more rapidly during the last hour as the battery voltage approaches the charger voltage.Does anyone have charge curves for AGM showing the performance (preferably with an 80A charger)? I'd particularly like to see the tail end of the charge cycle. How do AGMs perform? Is it significantly better than FLA batteries? Do AGMs taper the charge rate the way FLAs do, or is the entire advantage in the fact that I could run a bigger charger (100+ A) for my 460AH battery bank?Are there other advantages that AGMs offer?

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.

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)

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 batteryIt has about 85% of the usable capacity of a flooded batteryThen 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?

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.)

MEXICOWANDERER wrote:It is a lot heavier than a flooded batteryIt has about 85% of the usable capacity of a flooded batteryThen 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.

AGM batteries - are they better? | Good Sam Community

Almot
Explorer III
Nov 06, 2013
The thread subject was indeed "which is better", but the OP had clarified what exactly were his criteria of "better" - mostly the rate of charge and tapering close to the float stage.
beemerphile1
Explorer
Nov 06, 2013
harold1946 wrote:

I simply used the criteria provided by Deka to illustrate their overall rating.
The subject of the thread is, "which is better" meaning the battery itself, not which one is best in every application. Deka did not address that. Neither did I. :R

No need to be defensive. I did not criticize your post, only pointed out that different assets are important in different uses.

In reference to the thread title, there is no superior battery in every use. In my fleet of vehicles and RVs I use flooded, AGM, and Gel depending on the use.

If anyone wants to talk "better" or superior we should also include nickle and lithium batteries. Why limit the discussion to only lead/acid batteries?
harold1946
Explorer
Nov 06, 2013
beemerphile1 wrote:
harold1946 wrote:
Using the figures submitted by Deka and the 19 criteria, with the assesment values provided AGM's come out on top.
Ignoring cost and any specila charging requirements, this is where the evaluation comes out.
wet cell; 49/19=2.157
AGM; 59/19=3.105
Gel cell; 54/19=2.842
Draw your own conclusion.

Keep in mind that you cannot go strictly by that measure. Anyone looking at the list needs to weight the issues important to their particular use.

The chart you are looking at weights everything equally but in the real world some things are more important than others to an individual consumer.

I simply used the criteria provided by Deka to illustrate their overall rating.
The subject of the thread is, "which is better" meaning the battery itself, not which one is best in every application. Deka did not address that. Neither did I. :R
beemerphile1
Explorer
Nov 06, 2013
harold1946 wrote:
Using the figures submitted by Deka and the 19 criteria, with the assesment values provided AGM's come out on top.
Ignoring cost and any specila charging requirements, this is where the evaluation comes out.
wet cell; 49/19=2.157
AGM; 59/19=3.105
Gel cell; 54/19=2.842
Draw your own conclusion.

Keep in mind that you cannot go strictly by that measure. Anyone looking at the list needs to weight the issues important to their particular use.

The chart you are looking at weights everything equally but in the real world some things are more important than others to an individual consumer.
harold1946
Explorer
Nov 06, 2013
Using the figures submitted by Deka and the 19 criteria, with the assesment values provided AGM's come out on top.
Ignoring cost and any specila charging requirements, this is where the evaluation comes out.
wet cell; 49/19=2.157
AGM; 59/19=3.105
Gel cell; 54/19=2.842
Draw your own conclusion.
pnichols
Explorer II
Nov 03, 2013
Wayne,

Outstanding observations!

It seems to me that, given what you are saying, AGM batteries hands-down have at least that (tremenduous?) added advantage over FLA's ... which in many cases might mean that an RV'er who switches to them might not need to spend additional $$ to replace their stock single-stage 13.8V converter. Obviously I never replaced mine ... used the saved $$$ for other RV mods.

What you mention probably is related to two things:

1) Some AGM batteries are designed to be floated in the 13.5V-13.8V range.

2) All AGM batteries intrinsically have much lower internal impedance than FLA batteries ... hence AGM batteries, if needing a charge, can also suck up pretty good charge current at only their float voltages.
Wayne_Dohnal
Explorer
Nov 03, 2013

- They seem to defy all forum-knowledge by both floating and charging (when camping) from the same fixed voltage ... ~13.8 volts from a stock converter.
I saw this immediately when I put an Interstate AGM battery into the prior RV that used a Magnetek 7345, 13.8 volt converter. When discharged even slightly, the battery would pull pretty high current, then taper off to almost nothing when recharged. It appeared that a multi-stage charger would offer no benefit whatsoever. The specified float voltage for many AGMs is 13.5 to 13.8 at 77* F.
pnichols
Explorer II
Nov 03, 2013
full_mosey wrote:
We should get a free pass for early failure!

EITHER as you say ... OR (in my case) ... maybe AGM manufacturers consider use in a wheelchair as a mission-critical application requiring ultra-high design and/or construction quality (haha). ;)
full_mosey
Explorer
Nov 03, 2013
Hi Phil;

I converted beginning Jan 2009. If those are your first set of AGMs as is my situation, I would consider them a training set. We should get a free pass for early failure!

I bought three of them a year apart, after which I changed from a pop-up to a TT, and added two 12V fridges and solar to the mix with the current set. It is a stretch to call them a set as I grew into them; more an adventure.

HTH;
John
pnichols
Explorer II
Nov 03, 2013
I admit I'm heavily biased, now, towards AGM batteries for my motorhome MAINLY based on my personal experience with mine instead of what the experts publish:

- I bought 'em in the fall of 2006.

- They still do their thing on camping trips.

- There's never any corrosion around them.

- I never get holes in my pants if I brush up against them.

- They're never thirsty.

- I get to pay no attention to how far I draw them down before recharging.

- They seem to defy all forum-knowledge by both floating and charging (when camping) from the same fixed voltage ... ~13.8 volts from a stock converter.

- They're fully charged from the 130 amp Ford alternator (when driving) during 5-6 hours of travel.

Maybe it's because I screwed up by buying wheelchair AGM batteries instead of buying AGM batteries advertised to be for recreational vehicles. :h