AGM Baterries. Extravagant or Worth the Cost?

[scottyb]

I went the cheap route, purchasing 4 x 6V Energizer GC-2 batteries, when I upgraded my storage. Everything is contained and vented so no chance for spills or corrosion. My question is, are AGM batteries that much better? It seems like the cost is 3X that of lead acid batteries. Do they really last 3 times as long? To me, it really boils down (no pun intended) to the anual cost / Ah since periodically adding water and worrying about corrosion is not an issue. Are there other factors that make AGM's worth the price?

 

[Cjackg]

I am currently looking at replacing the junk Group 27 battery my dealer installed in my new 3110 and am considering an AGM. They are pricey but seem to have a much longer warranty period than std or GC lead acid batteries.

We dont often boondock and do have a generator so I am not interested in hauling a lot of batteries around but do want to be sure when I need 12v power there will be quick powerful response for the jacks, slides, etc.

 

[Lynn1130]

I would be interested in seeing what comes of this discussion since batteries, no matter what type, do not last more than 18 months to 2 years in Arizona. I have had trouble bring myself to spend that kind of money on batteries that will not last any longer that the golf cart batteries that I am now using.

 

[Jim.Allison]

I have no experience with AGM, but there are better batts than lead acid, if you can afford them. In my case, I have 166 lbs of batts in my batt cabinet. The weight is largely borne by the truck. If I had that weight behind the basement wall then i would be better off. But my lead acid prevents putting them back there because of gassing.

To learn more about house batteries, youtube is a good source. The "preppers", "doomsayers" and "off grid" crowd are building systems and they have posted a lot of information on youtube.

I will be watching this post with interest. My system is new and very functional, I would not change it, but I would be curious to know what a better system might be.

I went the cheap route, purchasing 4 x 6V Energizer GC-2 batteries, when I upgraded my storage. Everything is contained and vented so no chance for spills or corrosion. My question is, are AGM batteries that much better? It seems like the cost is 3X that of lead acid batteries. Do they really last 3 times as long? To me, it really boils down (no pun intended) to the anual cost / Ah since periodically adding water and worrying about corrosion is not an issue. Are there other factors that make AGM's worth the price?

 

[porthole]

AGM's have advantages, but only you can decide if it is worth the cost.

They can last a long time
The charge faster
reduced inspection
Can be mounted in any position
They tend to not crack and -or leak due to the AGM properties


They are sensitive to over charging.

 

[Jim.Allison]

There is no reason a house battery cannot last for several thousand cycles in any environment. In any house batt install, your charger must know the temperature of the battery in order to charge it. If there is no temperature sensor on your house battery then it is being overcharged when the battery is above 100 degrees and undercharged in the cool early morning desert temperatures. This leads to early failure. A true deep cycle house battery normally used in a 5th wheel should last for 5 to 8 years in any environment.

I would be interested in seeing what comes of this discussion since batteries, no matter what type, do not last more than 18 months to 2 years in Arizona. I have had trouble bring myself to spend that kind of money on batteries that will not last any longer that the golf cart batteries that I am now using.

 

[scottyb]

They can last a long time
The charge faster
reduced inspection
Can be mounted in any position
They tend to not crack and -or leak due to the AGM properties


They are sensitive to over charging.

That's the kind of information I was looking for. Of course the maintenance is obvious. I assume a good inverter/charger like a Magnum can addequately charge them? Are there different parameters to be set when charging them? I believe temperature monitors are standard with the MS 2012, right? I would like to know if anyone has experience with them lasting for many years beyond the expected life of lead acid batteries.

You are right, it like many other options. Is it worth the price of convenience to you.

 

[Lynn1130]

Good theory Porthole, but not real life here. In 40+ years of driving vehicles in Arizona I have seen one battery go more than 2 years before it died and that was a Japanese made quad battery. I have never had one of those do that since either. Want to conduct a survey to prove or disprove my observations, talk with any business that sells batteries here. Batteries usually give up about the middle of May when it gets nice and hot and they give little to no warning.

 

[brianharrison]

Yes, a good charger like the Magnum 2012 will adequately charge AGMs; charging voltages are similar to flooded however the low internal resistance of AGMs allows significantly higher charge amperages. I learned the other day about the Lifeline batteries having essentially no limit on charge rate (allowing faster recharge times). Each battery is different. My AGMS are limited to a continuous charge of 0.3 times C (Ah capacity at 10hr) . Most good inverter/charges are limited to 100 to 150 Amps continuous output.

I have not seen any research on changing up algorithms (ie bulk, adsorption, float) for AGMs vs flooded; however I know AGMs do not need to be equalized, as there is no fluid to stratify creating unequal voltages within the cells or between cells.

Brian

 

[scottyb]

Yes, a good charger like the Magnum 2012 will adequately charge AGMs; charging voltages are similar to flooded however the low internal resistance of AGMs allows significantly higher charge amperages. I learned the other day about the Lifeline batteries having essentially no limit on charge rate (allowing faster recharge times). Each battery is different. My AGMS are limited to a continuous charge of 0.3 times C (Ah capacity at 10hr) . Most good inverter/charges are limited to 100 to 150 Amps continuous output.

I have not seen any research on changing up algorithms (ie bulk, adsorption, float) for AGMs vs flooded; however I know AGMs do not need to be equalized, as there is no fluid to stratify creating unequal voltages between within the cells or between cells.

Brian

How long have you had yours. based on pricing I am finding on Lifelines, it looks like around $2.25 / Ah. If they last 10 years (big assumption), that's $0.225 / Ah / Year. Assuming GC-2's or T-105's will go 5 years (big assumption again), the cost would be around $0.16 - $0.26 / Ah / Year, depending whether you buy Energizers or Trojans.

Good theory Porthole, but not real life here. In 40+ years of driving vehicles in Arizona I have seen one battery go more than 2 years before it died and that was a Japanese made quad battery. I have never had one of those do that since either. Want to conduct a survey to prove or disprove my observations, talk with any business that sells batteries here. Batteries usually give up about the middle of May when it gets nice and hot and they give little to no warning.

Texas is not AZ, but we do get frequent 100+ days. Summer of 2011 we got 85 of them and 150 days over 90 degrees. With that said, I have a 12V gate opener and use a Group 27 Marine battery that is maintained by a battery tender from 110V. It is in a metal control box painted dark forest green and there is no telling how hot it gets inside during the day. It is only used for short durations a couple times a day and is rarely drawn down substantially. I have averaged about 3-4 years with them over a 14 year span.

 

[Jim.Allison]

Just to add here, my Xantrex which is similar to the Magnum has a remote display where you program your batt information which adjust the type of charging it provides. I dont know the range of batts that are available, but I'm sure that anything we would buy is included in that sophisticated system. Its been a while but I remember inputting the minimum voltage at which the charger would kick in, the amp hours of the battery bank the bulk charging rate, the absorption time, and float voltage. I got that information from the data sheet on the Trojan 1275's.

The Magnum has all of this stuff too, maybe more. So the upshot is that the custom battery feature is available so you dont have to rely on the defaults. From what I understand, many people do not know how far to push their batts during charging which leaves them undercharged, damaged and not up to the task when you need them the most. Solar is absolutely the best charging system around, but when that is not available these sophisticated 4 stage programmable chargers are a friendly and useful device. I use solar about 90% of the time and let the Xantrex do its thing when hooked to pedestal power or generator. BTW when all charging sources are being used the solar charger and inverter/charger work well together. The solar charger and TV charger also work well together, with minor hiccups.

As an after thought, It seems to me that a batt that accepts a bulk charge faster would be of benefit when charging off the generator in terms of fuel, and time on your generator. So one might factor in $30 of LP running the generator that it is going to take to charge a battery bank to 100% from 50%.

Ditto on equalization, there is debate there, but most literature I have seen indicates no reason to equalize batts other than conventional lead acid. If the batt manufacturer does not specify a thing then it does not exist in my mind.

Yes, a good charger like the Magnum 2012 will adequately charge AGMs; charging voltages are similar to flooded however the low internal resistance of AGMs allows significantly higher charge amperages. I learned the other day about the Lifeline batteries having essentially no limit on charge rate (allowing faster recharge times). Each battery is different. My AGMS are limited to a continuous charge of 0.3 times C (Ah capacity at 10hr) . Most good inverter/charges are limited to 100 to 150 Amps continuous output.

I have not seen any research on changing up algorithms (ie bulk, adsorption, float) for AGMs vs flooded; however I know AGMs do not need to be equalized, as there is no fluid to stratify creating unequal voltages within the cells or between cells.

Brian

 

[Ladiver]

How long have you had yours. based on pricing I am finding on Lifelines, it looks like around $2.25 / Ah. If they last 10 years (big assumption), that's $0.225 / Ah / Year. Assuming GC-2's or T-105's will go 5 years (big assumption again), the cost would be around $0.16 - $0.26 / Ah / Year, depending whether you buy Energizers or Trojans.

My Lifeline batteries were $1.43/Ah. Considering they are 6v, you need 2, so that makes it $2.86/Ah. BTW, that cost also included new mounting brackets.

 

[Jim.Allison]

Well cared for batts will last a long time, but 5 years is reasonable considering all points. More advanced batteries can cycle more than 50%. Conventional industrial lead acid can too, but at a price in longevity. IMHO and I mean MH opinion. The 6v concept is obsolete. I use twelve volts, my system is twelve volts, it makes things easy and there is no mathematical reason to use 6v, at least no reason that I have found. Im not saying I can't be corrected on this topic but I have been asking and no-one has ever been able to advise on this traditional use of 6v batts VS 12v.

My Lifeline batteries were $1.43/Ah. Considering they are 6v, you need 2, so that makes it $2.86/Ah. BTW, that cost also included new mounting brackets.

 

[Ladiver]

Some of the reasons against 12v that I have heard of is that you can get better performance/lb in 6v. I have heard that 6v discharge slower than 12v (I don't understand how that is possible).

Just for S&G's I decided to look for a 300Ah 12v battery or some smaller ones to give me the same capacity. I did find three things that convince me on 6v. 1. Cost 2. physical size 3. weight.

http://www.lithiumion-batteries.com...ion-battery/12v-300ah-lithium-ion-battery.php

http://www.surplusbattery.com/images/SPECSHEETS/PS12200.pdf

http://pvpower.com/uploads/products/8a4dltpspec.pdf

 

[JohnD]

My 2013 Heartland Trail Runner came with two batteries from the factory.

Fact is, I haven't given them much thought!

I am going to check them out thorougly tomororow and will report back then!

 

[Jim.Allison]

This is the problem, there is all kinds of myths out there, the math is what is important. So far I have not seen any math that points to why 2 6v are better than 1 12v. Im sure there is a legitimate debatable point here as people still believe in the multiple six volt system. I'm reviewing the link you provided. Thanks.

Some of the reasons against 12v that I have heard of is that you can get better performance/lb in 6v. I have heard that 6v discharge slower than 12v (I don't understand how that is possible).

Just for S&G's I decided to look for a 300Ah 12v battery or some smaller ones to give me the same capacity. I did find three things that convince me on 6v. 1. Cost 2. physical size 3. weight.

http://www.lithiumion-batteries.com...ion-battery/12v-300ah-lithium-ion-battery.php

http://www.surplusbattery.com/images/SPECSHEETS/PS12200.pdf

http://pvpower.com/uploads/products/8a4dltpspec.pdf

 

[Ladiver]

the math is what is important

This is where the problem comes in. What "math" do you want. Do you want 12v to be better or 6v? I learned many years ago, you can use numbers to prove anything you want. Lying with statistics creates excellent marketing!

 

[Jim.Allison]

Math as opposed to myth!!!!!!! Show me where it is better that a battery bank is better comprised of 6 volt batts. I am inviting ANYONE to show me that. I looked at all the angles when I built my solar charging system and all i could find were myths and assumptions. When you look at true RE deep cycle batts and compare 6's to 12's there is no real benefit except to complicate a simple system. As far as the numbers lying, its not that numbers lie but people interpret numbers incorrectly. Numbers never lie. They may appear to lie if you don't know how to do the math. I am sincerely open to this question. IF I made a bad decision, I want to know about it, I'm making an invitation. The math that I want is the only math that applies. if it shows 6's are better than 12's then so be it. But if people are building batt banks out of 6v because grandpa used 6v gc batts. Then its time for that thinking to go away.

This is where the problem comes in. What "math" do you want. Do you want 12v to be better or 6v? I learned many years ago, you can use numbers to prove anything you want. Lying with statistics creates excellent marketing!

 

[Ladiver]

Jim,

I really hope someone can put in some good input. I will never claim one is "better" than the other. I personally like the idea of 2 12v. If one dies, you are still OK. If one of my 6v's die, I am screwed! Luckily I have an aux 12v battery that normally rides with me for HAM radio work, so I really would not be up a creek.

The reason I went 6v was the "idea" given to me that they will charge faster, last as long or longer than a comparable 12v. I wanted a high quality battery that could be deep cycled many times. Both my installer and another battery tech (business associate) seemed to lean towards 6v. I will see if I can get more info from the battery tech. He services our UPS in our server room. I have a bank of 24 6v batteries there.

 

[Jim.Allison]

I have spent some time looking at the question. When I started my system I just wanted industrial deep cycle batteries, I studied the subject and rejected the 6v in series for the 12v in parallel. Then from there, I expanded my system all the way through solar. Although my solar supported electrical is strong and well designed, IT was only persistence and luck that made it that way. Let me explain

I did an energy survey and determined that I only needed 300 AH for my system (150 available)That was not based on having an inverter. See what I mean by luck. Turns out that with solar, 150 available AH is sufficient for my needs. I chose two 12v Trojans over the having 4 Trojan T105 GC (most popular GC batt for RV house batts).

I am more familiar with the whole subject today than I was 7 months ago when I started building my system. This is what I have learned tonight.

The 6v battery is a holdover from a time when 6v systems were the best choice. once there were only 6v and 8v. The 12v was considered hi-tech. 6v and 8v batts were the best way to store AH. But technology has brought us 12v batts that can provide efficient storage of AH. As the technology stands today, it is about equal whether you go 6v or 12v. But the 6v being 30% less in dollars makes it more attractive for large battery banks. Even in small battery banks it is significant. I did not realize this when I started on my system, I don't know if I would change it today.

3 T1275 Trojans, 450 amp hours, $660, 252 lbs, connecting cables $0, connecting weight cable weight 0 lbs, 293 square inches total foot print.

4 T105 GC Trojans, 450 amp hours, $424, 248 lbs, connecting cables required $50, connecting cable weight 10 lbs. 293 square inches total foot print.

To increase amp hours on the 6v system you have to add 2 additional batteries. To increase the amp hours on the 12v system you have to add only one. HOWEVER, the 6v system would increase by 225 amp hours the 12v only 150 amp hours. But adding two 12v instead of one would result in an increase of 300 amp hour increase.

Price is the only practical difference on large systems, there is really little reason if any for systems as small as ours. The question is not what voltage format is correct but what type of battery is the most efficient per pound per dollar.

Jim,

I really hope someone can put in some good input. I will never claim one is "better" than the other. I personally like the idea of 2 12v. If one dies, you are still OK. If one of my 6v's die, I am screwed! Luckily I have an aux 12v battery that normally rides with me for HAM radio work, so I really would not be up a creek.

The reason I went 6v was the "idea" given to me that they will charge faster, last as long or longer than a comparable 12v. I wanted a high quality battery that could be deep cycled many times. Both my installer and another battery tech (business associate) seemed to lean towards 6v. I will see if I can get more info from the battery tech. He services our UPS in our server room. I have a bank of 24 6v batteries there.