AGM Battery Homework

Topic: AGM Battery Homework (Read 3177 times) previous topic - next topic

AGM Battery Homework

July 27, 2015, 09:12:41 pm

In preparing for our coach's battery transplant from 2 MK 8D GEL's to 4 (East Penn/Deka/ MK) O'Reilly Super Start AGM8D's, I have been doing some homework regarding the care and treatment of these big boys. To recap what I have found out about the origin of these, East Penn makes their own labeled line and slaps on different labels for at least three other lines: MK MK Battery | 12 Volt 245 AH Deep Cycle AGM RV & Marine Battery, Deka http://www.remybattery.com/Intimidator-8A8D-Group-Size-8D-AGM-Battery-P4436.aspx
and O'Reilly Super Start AGM8D http://www.oreillyauto.com/site/c/detail/SSBL/AGM8D/N2493.oap?ck=Search_N2493_-1_-1&pt=N2493&ppt=C2389

If anyone has corrections or additions to this list, I am all ears! Also, feel free to check my math or question any of the parameters that I have put in there. I figure that there have already been several forum members who have gone this route (in particular, sourcing their 8D AGM batteries from O'Reillys due to easy availability and cost savings). In non-commerical use (my reading of it), O'Reilly Super Start heavy duty AGM8D batteries have 1 year free replacement warranty with no pro rating afterwards, where as Lifeline apparently has the free one year replacement as well as prorating up to 3 years, albeit, at a significantly higher out the door price. The Lifelines also have a slightly higher 20AH rating @255AH VS. 245AH for the East Penn family. Are the Lifelines better batteries? Probably, but maybe not enough better to justify the significantly higher cost in the eyes of some (me at least!). Besides, the battery technology I really wanted was the LifPo4 Lithium, but I had to conclude that now wasn't the time for it. For us there would be to much opportunity cost of doing other essential upgrades versus the resources I have available. For about $1,700, choosing 4 AGM8D's to reduce the depth of discharge cycles while still being able to boondock for extended periods of time seemed to me to be a good value proposition. To cut to the chase, I got these charging specifications and definitions from various East Penn documents, Solar/Off Grid Forums, Sailing forums, etc.

As an aside, I will add that I also had a bit of training in battery technology and maintenance from the navy, though there were no such things as AGM's and GELS in use there at the time. The ground crew used flooded lead acid batteries and the aircraft side used nicad batteries. I had training in both, but only worked on the aircraft side. The Nicad batteries were handled much like the LifPo4 batteries are today. They were comprised of individual nominal 1.25V cells bused together and contained in an outer case to make the 24vdc batteries (IIRC). The charging was done by very complex and large chargers which had a probe for each individual cell while monitoring both temperature and voltage with alarms to avoid the dreaded "thermal runway". Current LifPo4 technology is quite similar with a BMS system (Battery Management System), with a best practices to have a monitor on each individual cell, but is sometimes done on pairs of cells to cut costs and complexity. Enough said on that!

Anyway, I have made myself a cheat sheet of sorts to aid in the charging setups for our fairly complex system of a Solar Charge Controller, Magnum MSH 3012 Hybrid Inverter Charger, as well as a (sort of) stand alone Sterling 40amp marine charger used to balance individual batteries in combination with my Solar 1000 amp carbon pile load tester (Solar in this case is the brand name, and has nothing to do with solar power), and when this project is finally done, a Sterling battery to battery charger or perhaps the Sterling alternator to battery charger and maybe one or two more devices. The cheat sheet is as follows and is also included as a pdf attachment below... looking for comments, corrections, and suggestions.
Thanks, Don

AGM Charging parameters mostly from PDF http://www.dekabatteries.com/assets/base/1913.pdf
East Penn/Deka/MK AGM 8D = O'Reilly Super Start AGM8D

1.) Bulk Charge (Max 73.5A @ Max 14.4vdc) C20 = 245AH
30% of C20 @1.75 volts per cell (12V = 10.5V @ 1.75vpc)
Charge Current @ 30% of C20 is .3 X 245 = 73.5A @ Max 14.4vdc
Max Time (Hr) = Ahr x 1.2 / Avg. Current (A) - Voltage limit equal to Absorption (Regulation) Stage limit

2.) Absorption Stage (Constant Voltage)
2.35 - 2.40 vpc (14.1- 14.4vdc)
Charge until change in current < 0.10A per Hr / Max Time: 12Hr

3.) Float Charge (Constant Voltage)
2.24 - 2.26 vpc (13.44 - 13.56vdc)
No Time Limit

4.) Equalize Charge (Constant Voltage)*
2.40 - 2.43 vpc (14.4 - 14.58vdc)
Charge until change in current < 0.10A per Hr / Max Time: 12Hr

*Note that what East-Penn considers an "equalization" is just an elevated absorb voltage, ie 14.4 to 14.6, and NOT anything over 15 volts.
Temperature Coefficient = -3mV/cell/°C1
1 Minimum charge voltage limited to 35°C (95°F), Maximum charge voltage at 15°C (59°F) Voltage Limits shown based on 25°C (77°F)

Re: AGM Battery Homework

Reply #1 – July 27, 2015, 09:26:06 pm

How many charge discharge cycles have the two current AGM's gone through?

Re: AGM Battery Homework

Reply #2 – July 27, 2015, 09:36:30 pm

All four were bought within two weeks of each other and the two already put in the coach haven't had any in use discharge cycles yet as we haven't used the coach and it is hooked up to power. The resting voltages are all within 2 100th's of a volt of each other (12.91 to 12.93vdc). This is after load testing each, charging with a three stage charger at the rates posted, and voltage checked the resting at least 12 hours.

Quote from: Caflashbob – July 27, 2015, 09:26:06 pm

How many charge discharge cycles have the two current AGM's gone through?

Re: AGM Battery Homework

Reply #3 – July 27, 2015, 09:45:09 pm

Perfect.

Re: AGM Battery Homework

Reply #4 – July 27, 2015, 09:52:45 pm

Not sure if NAPA is having the Second Saturday Early Bird 7-9AM 30% Off Sale in your end of the country??

Here in Houston, I'm waiting for Aug 8.. $400= a deal on an AGM battery.. (I'll have 2 BTW.)
Yes, it is the EAST PENN Battery (Gel, AGM or Lead Acid).. pc

Re: AGM Battery Homework

Reply #5 – July 27, 2015, 10:29:43 pm

Do you have the NAPA part number for their AGM 8D battery?

Re: AGM Battery Homework

Reply #6 – July 27, 2015, 11:55:59 pm

Is this the battery you are looking at?
Deka 8A8D AGM Battery - 8D Marine Battery
Their list on it is pretty high, only about $25 or less than the 8D Lifelines. Still, $400 apiece is a great deal, the same as what O'Reilly sells them for with the 10% military discount. Without a special discount of some kind, O'Reilly has the best price by far @ $449 ea. You just have to deal with the know nothing parts guy and give them their own part number (AGM8D), or they'll never find it. Then of course, there is basically no information from the O'Reilly website as to charging parameters etc. I don't know about Napa, but if it is branded as East Penn, Deka, or MK, you can at least be sure that you have the right info on the battery specs. At O'Reilly's, you have to do some sleuthing to work it out and trust your own assessment... which is why I wanted to make an (hopefully) informational post about them and then let the wisdom of the (FoFum) crowd vet the information. Anybody have something to add?

Don

Quote from: pocketchange – July 27, 2015, 09:52:45 pm

Not sure if NAPA is having the Second Saturday Early Bird 7-9AM 30% Off Sale in your end of the country??

Here in Houston, I'm waiting for Aug 8.. $400= a deal on an AGM battery.. (I'll have 2 BTW.)
Yes, it is the EAST PENN Battery (Gel, AGM or Lead Acid).. pc

Re: AGM Battery Homework

Reply #7 – July 28, 2015, 10:55:49 am

Quote from: Don & Tys (AKA acousticart) – July 27, 2015, 11:55:59 pm

Is this the battery you are looking at?
Deka 8A8D AGM Battery - 8D Marine Battery
Their list on it is pretty high, only about $25 or less than the 8D Lifelines. Still, $400 apiece is a great deal, the same as what O'Reilly sells them for with the 10% military discount. Without a special discount of some kind, O'Reilly has the best price by far @ $449 ea. You just have to deal with the know nothing parts guy and give them their own part number (AGM8D), or they'll never find it. Then of course, there is basically no information from the O'Reilly website as to charging parameters etc. I don't know about Napa, but if it is branded as East Penn, Deka, or MK, you can at least be sure that you have the right info on the battery specs. At O'Reilly's, you have to do some sleuthing to work it out and trust your own assessment... which is why I wanted to make an (hopefully) informational post about them and then let the wisdom of the (FoFum) crowd vet the information. Anybody have something to add?
Don

Have to agree with you about the o'reilly 8d agm, online no information, had to go to store and special order. Bought 4 over
a years time. Waited till I received an o'reilly discount card in the mail, and used it to buy for about $410 ea. Stupid me, forgot
all about the military discount. Nice thing about o'reilly's is they will take anything for a core. Had an old office ups with 4 ah
batteries in it, and they took a 2 lb battery for the core trade on a 8d.

Re: AGM Battery Homework

Reply #8 – July 28, 2015, 11:10:49 am

Good point about the core... I turned in one of my old red tops that was completely gone when I bought the first of 5 of these AGM8D's to replace the two defunct Red top Optimas (One 8D equals two of the Optima Red tops in size, somewhat less cranking amps than the two combined red tops, but simplified the cabling and the thing spins like a top at start up now and never did with the two red tops). Got my $22 core charge back

Also, you get some O'Reilly rewards back. When I bought 3 of the 8D's at once, I got $150 back to spend at O'Reillys. You have to use it all at once unfortunately, but I had no trouble loading up with stuff to use the $150

Don

Quote from: jcus – July 28, 2015, 10:55:49 am

Nice thing about o'reilly's is they will take anything for a core. Had an old office ups with 4 ah
batteries in it, and they took a 2 lb battery for the core trade on a 8d.

Re: AGM Battery Homework

Reply #9 – July 28, 2015, 12:12:48 pm

I have two 8D AGM batteries for the house. I just went out to look, and I can't see any label that says how many AH they have. Anyone have an 8D accessible to find out? We're talking about adding solar panels some day.

Re: AGM Battery Homework

Reply #10 – July 28, 2015, 12:19:05 pm

Every 8d agm I have every looked at is between 210 and 250 amp hour capacity, or this
is what is on the label. 2 8d's with enough panels and a good inverter should be enough to
run a frig or freezer.

Re: AGM Battery Homework

Reply #11 – July 28, 2015, 12:23:07 pm

What brand are they and what color are they? The all grey Dekas and MK's are Gel batteries made by East Penn. The AGM's made by East Penn whatever the brand label are grey with a black top. The Gels are rated at 225AH and the AGM's are rated at 245AH. Whatever the brand, if they are 8D's and AGM's they are probably at least 225 with the max I have seen at 255AH (Lifelines). The actual capacity would have to be tested if you want real world numbers. New batteries take several cycles to reach their full capacity.
Don

Quote from: kb0zke – July 28, 2015, 12:12:48 pm

I have two 8D AGM batteries for the house. I just went out to look, and I can't see any label that says how many AH they have. Anyone have an 8D accessible to find out? We're talking about adding solar panels some day.

Re: AGM Battery Homework

Reply #12 – July 28, 2015, 01:01:38 pm

Don... thanks for all that information in one easy-to-search spot here.

We're still running wet-cell 8Ds in our coach since our use is just weekend camping with one longer trip each year until the DW can retire in 2017. At that point I'll decide whether to go for AGM or LiFePo. The solar charge controller we bought (Classic 150) is pretty easy to configure for any type of battery but if I go to Lithium I'm not at all sure how to deal with the engine-driven alternator. Maybe just let the solar panels do that job all the time.

I'm watching this tech closely as it seems like the wrong choice can turn out to be expensive. So, for that matter, can the right choice.

Craig

Re: AGM Battery Homework

Reply #13 – July 28, 2015, 02:10:58 pm

Don, mine came from O'Reilly's, and are grey with black tops. Craig, not only are they expensive, but they are also heavy. Take your coach in and have the young guys change the batteries for you.

Re: AGM Battery Homework

Reply #14 – July 28, 2015, 02:34:04 pm

Are you sure that these O'Reilly batteries are actually deep cycle batteries? The ad seems to make them out to be starting batteries.

Re: AGM Battery Homework

Reply #15 – July 28, 2015, 04:44:55 pm

Here's the label on the O'Reilly AGM8D battery, in case it helps answer any questions:

Re: AGM Battery Homework

Reply #16 – July 28, 2015, 04:47:45 pm

These East Penn manufactured AGM heavy duty commercial batteries are advertised in various ways depending on the label that is slapped on them. They aren't a true deep cycle battery as near as I can tell, not like Rolls-Surrett, Trojans, etc.. However according to East Penn, they have excellent deep cycle characteristics, (Brochures below) and also have good starting capabilities (1450 CCA). If the specifications are accurate and the 245 AH @ the 20 hour rating is correct, then I believe that they will make excellent house batteries. In fact, I have bet over $1,700 on that assessment. I am not recommending that anyone else do the same, that is up to each persons assessment of the information. Why I wanted to post the information that I have come up with is to basically crowd source the wisdom (or lack thereof) of my conclusions and see if anybody can add to it or offer information that counters my assessment. Ultimately, I hope that time will show this purchase to be a good value. I know that house battery banks rank pretty high on the priority list of many, if not most coach owners and so I hope that posting this info will aid others in making their decision. Every single specification published by East Penn lines up exactly with what O'Reilly's has on their website. Additionally, I researched online who made various lines of batteries for the house brands and what I found corroborated my conclusions. I am not just going by the fact that the case is identical in appearence. Most significantly, every single metric regarding temperature, reserve capacity (Reserve Capacity @ 25 amp discharge rate: 517 mins), cold cranking amps (1450 CCA measured at 0º F), marine cranking amps (1800 MCA measured at 32º F), etc. So the fact that O'Reilly's doesn't tout these batterie's deep cycle capability doesn't concern me as that is in the specifications, though the webpage does state that the battery is suitable for "Starting and heavy cycling power". But all this is just my assessment and so anyone contemplating going this route needs to weigh the pros and cons of investing in something that hasn't been specifically advertised as appropriate for the purpose they have in mind for it. I do it all the time, and it is true that I have been burned by inaccurate specifications at times in the past. By and large however, I have benefited by going the "off label use" route (to borrow a phrase from big pharma) over the course of my life to come up with creative solutions for thorny problems.
Don

Quote from: rsihnhold – July 28, 2015, 02:34:04 pm

Are you sure that these O'Reilly batteries are actually deep cycle batteries? The ad seems to make them out to be starting batteries.

Re: AGM Battery Homework

Reply #17 – July 28, 2015, 05:51:39 pm

Thanks.

Here is where you can download the spec sheets for the MK Deka batteries, if they are the same as the O'Reilly's.

MK Battery: RV/Marine Products
http://www.mkbattery.com/images/8A8D.pdf
http://www.mkbattery.com/images/8G8D.pdf

Of note should be that the MK Deka 8D AGM has a lifespan of about 750 cycles at 50% DOD (depth of discharge). The 8D gel is about 1000 for the same.

A FullRiver 8D DC260-12 deep cycle battery has about 1300 cycles for the 50% DOD. Fullriver Battery DC260-12 Product Information

Just throwing some information out there for you.

Re: AGM Battery Homework

Reply #18 – July 28, 2015, 06:23:33 pm

Thanks for adding some useful info to the thread! The full river battery specs even better than the Lifeline by a smidgen or two, but shares a similarly high price. Three of these would have cost about $400 more than the 4 of O'Reilly's/MK/Deka/East Penn, but may still be a good value and if I was doing blue water cruising, I would probably spring for something like this. Nice to be able to find an O'Reilly's-Napa-Autozone type place on the road and replace one of these East Penn Variants in short order, and relatively cheaply. Just my opinion... If money were no object, I would have sprung for a LifPo4 option for sure. As it is, I anticipate sometime in the next few years, I will do that anyhow and I think the current set of AGM's will still have lots of life left and will be repurposed or sold. Interesting times we live in...
Don

Quote from: rsihnhold – July 28, 2015, 05:51:39 pm

Thanks.

Here is where you can download the spec sheets for the MK Deka batteries, if they are the same as the O'Reilly's.

MK Battery: RV/Marine Products
http://www.mkbattery.com/images/8A8D.pdf
http://www.mkbattery.com/images/8G8D.pdf

Of note should be that the MK Deka 8D AGM has a lifespan of about 750 cycles at 50% DOD (depth of discharge). The 8D gel is about 1000 for the same.

A FullRiver 8D DC260-12 deep cycle battery has about 1300 cycles for the 50% DOD. Fullriver Battery DC260-12 Product Information

Just throwing some information out there for you.

Re: AGM Battery Homework

Reply #19 – July 28, 2015, 07:04:21 pm

Don:

Also considering new AGM house batteries. I have the Progressive Dynamics 9280 charger and pendant:

Progressive Dynamics 9280

Pendant

It doesn't seem to have an AGM setting (at least that I can see). In the research you have done, do you think I will need a more advanced charger, I was hoping to stay with this one. I have 2 house batteries, so theoretically the highest rate of charge would be 40 amps per battery in the "Boost" mode.

Re: AGM Battery Homework

Reply #20 – July 28, 2015, 09:33:44 pm

Quote from: prfleming – July 27, 2015, 10:29:43 pm

Do you have the NAPA part number for their AGM 8D battery?

NAPA PN 9275 (AGM/8A8D)
PN from Troy Steerling (East Penn/NAPA Rep in Houston) 832-888-3399

Which battery charger?
After I visited with Trojan, East Penn, etc., etc;
they all suggested the 12V-10AMP INTERACTOR was the charger to have (until someone comes up with a
better design.) This charger was designed with/for Wet & AGM style batteries and had internal DIP Switches that need to be set to 14.1V if the charger is to be used with a GEL type battery ($149.99.)

Additionally info after visiting with a Lifeline Battery wholesale source.
Unless you were full timing, the East Penn AGM battery was a better choice than the Trojan AGM FWIW. pc

Re: AGM Battery Homework

Reply #21 – July 28, 2015, 09:46:10 pm

The MK engineer last year mentioned that penn had changed the plate mounting inside the battery and expected to double the cycle life's of both the AGM and Gels.

He mentioned getting numerous calls from us foretravelers with 10-12 year old batteries already.

Their was a change date but he did not have it readily available but it was around two years ago?

Re: AGM Battery Homework

Reply #22 – July 29, 2015, 01:14:37 am

Peter,
I had a quick look at the PD charger and pendant and it doesn't appear to be suitable for anything but flooded lead acid as far as I can see. The Desulfation Mode when the charger is put in storage mode would be an AGM or Gel killer. Battery type setting aside, having the ability to adjust the charging voltage and current gives you the ability to charge almost any battery if you set them up right. Batteries are just too big of an investment to take chances, IMHO. Check out the Sterling ProCharge units. In addition to 11 or so preset charge profiles, there is one custom setting you can program as well. While not cheap, they are much less than anything else with that degree of flexibility that I have been able to find. A commercial member of the forum, Alan at Bay Marine supply, generally has a ForeForum discount. I have found him to be very willing to help with information and if he doesn't know the answer about a product he sells, he knows who to call to get the answer and is happy to do it.
Here is a link to the one I bought... Alan has a pretty informative video that he made himself showing the operation and features of that line of Sterling chargers.
Sterling ProCharge Ultra 40 Amp Battery Charger | 0
Don

Quote from: prfleming – July 28, 2015, 07:04:21 pm

Don:
Also considering new AGM house batteries. I have the Progressive Dynamics 9280 charger and pendant:
Progressive Dynamics 9280
Pendant
It doesn't seem to have an AGM setting (at least that I can see). In the research you have done, do you think I will need a more advanced charger, I was hoping to stay with this one. I have 2 house batteries, so theoretically the highest rate of charge would be 40 amps per battery in the "Boost" mode.

Re: AGM Battery Homework

Reply #23 – July 29, 2015, 03:19:32 am

I looked at the warranty info for that part number on Napa's website (you need to download the PDF to read the fine print!), and though it mentions a 2 year warranty which at first blush sounds better than O'Reilly's 1 year free replacement, the pdf indicates that this part number (9275) is prorated after just three months. You almost need to be a lawyer to figure out what protection you have, so maybe I read it wrong but something to take into account...
Don

Quote from: pocketchange – July 28, 2015, 09:33:44 pm

NAPA PN 9275 (AGM/8A8D)
PN from Troy Steerling (East Penn/NAPA Rep in Houston) 832-888-3399

Re: AGM Battery Homework

Reply #24 – July 29, 2015, 02:38:48 pm

I called Progressive Dynamics and their tech support told me a jumper can be put on the board that drops the voltage 0.4 volts to make the charger compatible with gel batteries, but the charger is fine for wet and AGM batteries without it.

Affiliate Notice