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Discussion Starter · #1 ·
I need to replace my house bank, which is currently two Group 27s (~110Ah each when new, approximately 0 presently). So I'm looking at golf cart batteries.

I've been presented with an opportunity to buy four GPL-4CT (Lifeline Batteries - Marine & RV Deep Cycle Batteries) used AGM batteries, two years old, that test out well, for $100 each (that's all I know; I don't know what sort of test or how many cycles, etc). These had 220Ah capacity when new, I'm not sure what they're at now. Would you do it? I live aboard, and mostly daysail, but at least once a summer go on a 3-5 day journey usually without shore power. I have a 40A charger and a 65A (?) alternator. Does this sound like an OK idea? I'm probably also going to sell my boat within 2 years (thought it was going to be this year, but likely not...), so I'm looking to not spend a ton of money.

The recommendation from the local battery dealer was Deka GC25s, new, for $170/ea. These have 235Ah capacity, so I only need two to replace my current bank, but I'd really like more capacity... I also really don't want to spend as much as four would cost, so all told if I went with this option I'd probably only buy two of them.

Cost and capacity both seem to be telling me to buy the AGMs, but if they don't last out at least two years, then it will have been a waste of money. What do you think?
 

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I have no direct experience with marine AGM (I do have them on my Prius accessory battiries), so take my advice with a huge grain of salt (preferably Lead Sulfate lol): I've read that AGMs require a more sophisticated charger system, so you should factor that into your overall cost if your charger does not meet AGM requirements. As for what those requirements are, you will need to research it or wait for more expertise here.
 

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Seems that AGMs are easier to ruin with bad use practices so I would be very cautious. If I personally knew the past owner and there habits I might. But $100 seems steep for used, given you don't know the history. Is there any warranty. (either original OE or from seller?) Why is the person getting rid of them?

I would look at Sam's Club golf cart batteries. I believe that is what Mainesail recommends and are around $84 to $112 each.
 

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I need to replace my house bank, which is currently two Group 27s (~110Ah each when new, approximately 0 presently). So I'm looking at golf cart batteries.

I've been presented with an opportunity to buy four GPL-4CT (Lifeline Batteries - Marine & RV Deep Cycle Batteries) used AGM batteries, two years old, that test out well, for $100 each (that's all I know; I don't know what sort of test or how many cycles, etc). These had 220Ah capacity when new, I'm not sure what they're at now. Would you do it? I live aboard, and mostly daysail, but at least once a summer go on a 3-5 day journey usually without shore power. I have a 40A charger and a 65A (?) alternator. Does this sound like an OK idea? I'm probably also going to sell my boat within 2 years (thought it was going to be this year, but likely not...), so I'm looking to not spend a ton of money.

The recommendation from the local battery dealer was Deka GC25s, new, for $170/ea. These have 235Ah capacity, so I only need two to replace my current bank, but I'd really like more capacity... I also really don't want to spend as much as four would cost, so all told if I went with this option I'd probably only buy two of them.

Cost and capacity both seem to be telling me to buy the AGMs, but if they don't last out at least two years, then it will have been a waste of money. What do you think?
The only way to know "test out well" with Lifeline AGM's is to do a controlled 20 hour capacity test. Seeing as Lifelines can EASILY be toasted in two years, I would not buy used AGM's that had not had a controlled 20 hour capacity test. Even the Midtronics instruments do not correlate well to "capacity" on Lifeline's. Sure they can easily spot a bad battery or differences between batteries but a 10-20% loss in capacity, not as well...

With Lifelines, I capacity test them....

As an example I just last month capacity tested and conditioned the bank of four Lifline's for my brothers boat (same batteries 4CT's). Under a controlled 20 hour test they are coming in at just about 88% of rated capacity. Using the Midtronics they still test as basically new yet really have lost 12% of their capacity or about 26Ah's.

How much height do you have? I have a set of brand new Full River DC335 AGM 6V's that are 335Ah? Customer changed his mind.... These are the same foot print as a Trojan J305 series, or in between a T105 and an L16... They are a heck of a deal for someone who can fit them...

If used batteries are free or nearly free, go for it, but if they want more than $40.00 each I'd pass it up without a way to do a capacity test..

BTW the Deka DC25 is a flooded battery not AGM. It's smaller sibling the GC15/230Ah can be bought at Sam's Club under the Duracell EGC2 label for about $109.00....

This price was a few years ago.. This is a Deka GC15 with a Duracell sticker...


The best value in the Northeast is Deka/Duracell at Sam's Club. The Seabrook store would also have no tax. That said the Deka AGM is not the same quality battery as a Lifeline or an Odyssey AGM but they make a decent reserve or starting battery and if not cycled too hard can even make a decent house battery.
 

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Discussion Starter · #5 ·
Thank you all for the info. I'm not married to the idea of an AGM, and in fact would prefer a flooded or gel battery, but $100/battery seemed like it might be too good to pass up. If I could get new flooded cell batteries for around the same price, I'd go that route! My charger is a Xantrex Freedom HF 1800, which has an AGM mode. The previous owner is getting rid of them because he's upgrading to a bank of 8 L16s.

The area I can dedicate to batteries measures about 20" x 26" x 13" (height), though I can get a little taller in part of it. That's really close to the size of those batteries, Maine Sail... I wonder if I could squeeze two of them in.

The GC15 is only 5Ah less than the GC25? That seems like a tiny capacity loss for such a huge difference in price. I might have to get myself a Sam's Club membership... any idea if Costco carries similar ones? I already have an in there :)
 

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I switched to AGMs due to the limited locations for batteries in my boat and the helpful nature of being able to lay AGMs on their side.

Since AGMs are so picky about charging I'd hestitate from buying used ones unless I knew the seller and how they had been cared for.

When I bought my AGM batteries I also added a good multi-stage alternator regulator (about $200, alternator modification, and a fair amount of wiring work) and switched my shore power charger to the AGM setting.
 

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Thank you all for the info. I'm not married to the idea of an AGM, and in fact would prefer a flooded or gel battery, but $100/battery seemed like it might be too good to pass up. If I could get new flooded cell batteries for around the same price, I'd go that route! My charger is a Xantrex Freedom HF 1800, which has an AGM mode. The previous owner is getting rid of them because he's upgrading to a bank of 8 L16s.

The area I can dedicate to batteries measures about 20" x 26" x 13" (height), though I can get a little taller in part of it. That's really close to the size of those batteries, Maine Sail... I wonder if I could squeeze two of them in.

The GC15 is only 5Ah less than the GC25? That seems like a tiny capacity loss for such a huge difference in price. I might have to get myself a Sam's Club membership... any idea if Costco carries similar ones? I already have an in there :)
Just show them your Costco membership, tell them you want to evaluate the club (not happy with Costco etc., and ask for a one day trial pass.....

Costco generally sells Johnson Controlls (JCI) batteries which are not quite the quality of the Deka/East Penn product.
 

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After having used T-105 golf carts for more than 20 years, last year in August I replaced all my house batteries with Crown industrial golf-cart batteries. They are rated at 235AH each. I also replaced my Group 31 starting battery, again using Crown. Total cost for six golf carts and one group 31 was $752, including 6% sales tax (at Stevens Battery Warehouse in Annapolis).

Crown batteries are made in the US (OH, I believe) and are of excellent quality.

So far so good. Will be doing periodic testing of these as the season progresses.

Bill

FWIW, Deka (East Penn) and all its brands have been having some problems of late. I wouldn't buy them right now. For example, about 12 AGM batteries in the local West Marine store -- of different sizes, from little ones to big ones -- ALL had resting voltages FAR BELOW what you would expect for batteries dated 1-3 months previous. Furthermore, they would not take a charge properly. Have no idea what the problem is/was, but it's clear there WAS a problem, as others have reported.

B.
 

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Like Maine said, not without a load test. Its like buying somebody's leftover pizza without being able to look in the box. (Or as they used to say, a pig in a poke.) If the guy is local to you, doing a test may be no problem and you may find a bargain. Lifeline makes a top quality product, if it was not abused.

Costco's battery policy apparently depends on the store manager. There's no uniform stock, and at least at the stores (plural) I've called, no one will check inventory, you have to simply go in and see what they have. A most peculiar and lousy way to do business, most unlike Costco, but that's what I've seen again and again, not just at one store. You'd figure in this day and age you could at least "order now and pickup when it arrives" the same way they sell tires, but no, you can't do that either.

But it could be worth talking to the seller, odds are he'll get very few offers and he'll be open to discussion.
 

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Like Maine said, not without a load test...
Maine suggested a 20 hour capacity test. A "load test" is a very different thing, as it is meant to simulate the high current draw of a car/truck's starter battery. These batteries could easily pass the latter, yet fail the former.
 

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Non starter for me, capacity test or not. I'm not buying used batteries for anything other than a tag sale deal. Who knows how they were treated, charged, deep discharged, etc. Free or an inconsequential amount of money at best.

Also, while I'm no expert (some of this stuff gives me a headache), I learned enough about switching to AGMs a couple of years back, that I skipped it. The alternator and charger upgrades were simply prohibitive to me. Any advantage did not justify. You can burn out an alternator, if your system is not set up to charge AGMs. That would be an expensive bummer for buying discount used AGMs.
 

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Discussion Starter · #14 ·
Well, you seem to have done a pretty good job of swaying me towards new flooded cell batteries. Regarding the gel vs flooded, from what I've read, gel batteries have many of the advantages of AGM (sealed, maintenance free, etc), with far fewer of the drawbacks (less damaged by deep draw, less demanding charging). So that's why I'm still willing to entertain the idea of them. If I buy new batteries, they'll almost certainly be flooded cell. I guess I better go check Costco and Sams Club. Thanks for the help!
 

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Well, you seem to have done a pretty good job of swaying me towards new flooded cell batteries. Regarding the gel vs flooded, from what I've read, gel batteries have many of the advantages of AGM (sealed, maintenance free, etc), with far fewer of the drawbacks (less damaged by deep draw, less demanding charging). So that's why I'm still willing to entertain the idea of them. If I buy new batteries, they'll almost certainly be flooded cell. I guess I better go check Costco and Sams Club. Thanks for the help!
GEL and flooded deep cycle also out-cycle AGM.... GEL does require lower charge voltages though so like AGM you still need to be set up for it. I have one bank of GEL's going into their 15th year this spring the only other bank that has even come close to that cycle life is Rolls 5000 series but these are MASSIVE batteries...............
 

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I have no direct experience with marine AGM (I do have them on my Prius accessory battiries), so take my advice with a huge grain of salt (preferably Lead Sulfate lol):
Oddly enough the ONLY thing, that is non-routine maintenance, that has gone wrong with my Prius in 140K is the AGM accessory battery and it is now about ready again......:mad: Nothing but the AGM accessory battery has failed on that car.

My wife's car, with 170K, still has the factory original flooded Honda battery that is now 8 years old........
 

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"Maine suggested a 20 hour capacity test. A "load test" is a very different thing, as it is meant to simulate the high current draw of a car/truck's starter battery."
Not at all. The common load test that you are talking about uses a high load for a short time. A 2-hour capacity test uses a lower load for a longer time, but it is still a LOAD TEST used to measure capacity.
That might be different jargon to a power engineer, but in plain English, they're both load tests, just using different sized loads for different times.
 

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"Maine suggested a 20 hour capacity test. A "load test" is a very different thing, as it is meant to simulate the high current draw of a car/truck's starter battery."
Not at all. The common load test that you are talking about uses a high load for a short time. A 2-hour capacity test uses a lower load for a longer time, but it is still a LOAD TEST used to measure capacity.
That might be different jargon to a power engineer, but in plain English, they're both load tests, just using different sized loads for different times.
My point was that if OP takes his battery into a battery dealer and asks for a "load test," he will likely walk out with the wrong information. Like you said, the short duration 100-amp load test is the "common load test." If he decides to find someone to test the used batteries for him, he MUST be specific in asking for a "20 hour capacity test."

I agree that both tests involve a "load" in the electrical sense of the term. But the nature of that load is very different in the two tests.

I have never heard of a "2-hour capacity test". I thought that the industry standard was a 20 hour test. You can choose to drain the whole battery in 2 hours if you want to, but you may have difficulty comparing this result with the battery's original 20 hour rating, which is what you need to do to assess whether the battery has been abused by the first owner.

I think jargon is important in this case. These words are not inconsequential - they have real meaning that affect the test conditions, and thus the test results.
 

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"Maine suggested a 20 hour capacity test. A "load test" is a very different thing, as it is meant to simulate the high current draw of a car/truck's starter battery."
Not at all. The common load test that you are talking about uses a high load for a short time. A 2-hour capacity test uses a lower load for a longer time, but it is still a LOAD TEST used to measure capacity.
That might be different jargon to a power engineer, but in plain English, they're both load tests, just using different sized loads for different times.
A carbon pile load test tells you nothing about the actual Ah capacity of the battery. It is a short duration "impulse" or cranking amp test but does nothing to tell you how many Ah's your battery can deliver over long durations at lower loads. It is an utterly useless test in terms of knowing anything about the physical capacity of cycling banks. If you need to know the battery can start your Camaro then ok, but for cycling banks, a useless test unless looking for dead/alive but capacity unknown.

I have batteries that pass carbon pile tests with flying colors that have lost 30% + of actual Ah capacity. I have tested 100Ah batteries that pass a carbon pile test that come in at just 60Ah's of capacity...

The only accurate way to know if a battery has lost Ah capacity is to do a controlled 20 hour test or a reserve capacity (RC) test which is a 25A load for the batteries rated minutes.

All a typical "load test" tells you is if the battery can start an engine, which is easy.

A 20 hour capacity test is a 20% of "C" as a load until the battery hits 10.5V and you count Ah's delivered during this test or count time. Counting Ah's and using a relay to terminate the load at 10.5V is much easier.

or

25A for XXX rated minutes or until battery voltage hits 10.5V - count minutes before battery hits 10.5V. This requires human attention for the duration and with used batteries may not always translate as well to house bank loads, which are usually closer to the 20 hour rate...

If the battery is rated at 5 hours or 10 hours these can also be tested and the test is shorter but the amperage higher..

Controlled capacity tests are not easy and you need the equipment to do it, which most boaters don't have nor do typical battery shops........ Concord battery will happily sell you a tester for $3000.00 plus dollars but they are optimized for the aircraft tests which is a different rate.....:D

The Midtronics/impedance analyzers come closest on FLA batteries but do not work as well on GEL or AGM to translate to actual Ah capacity. They more closely correlate however than does a carbon pile test.

20 Hour Capacity Test - 100Ah Battery:

#1 Battery allowed to warm to 75F to avoid temp compensation calculations and mimic factory testing. I set my testing room at 75F to make this easier.

#2 Battery charged to full & current allowed to fall to 0.5% of "C" at 75F and rated absorption voltage. This is 0.5A at 14.XV for what ever the particular battery requires..

#3 Ah/Coloumb counter reset to 0.

#4 A load of 5A is applied to the battery and this 5A load is held constant (requires manual manipulation to maintain 5A as terminal voltage falls) or a custom built adjustable load cell.. The test load applied to the battery is determined by: Rated Ah capacity divided by 20 or 100Ah/20=5A. A 225Ah battery would be 225Ah/20=11.25A load.

#5 Test load is terminated once battery terminal voltage hits 10.5V

#6 Record Ah's delivered and compare to the factory rated 20 hour capacity. If you lack an Ah counter you count hours & minutes but this is very tedious....

#7 Recharge battery at 20 hour rate or a charge rate of 5A for a 100Ah battery or 11A +/- for a 225Ah battery....
 

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No, I wasn't getting a dealer involved in this at all. That means hauling lead to and from and back again, multiple trips and grunts. Nuh-uh. There's usually a way to scrounge a load and leave the batteries where they are. (Especially if they're still in the original owner's boat.) And really, even a shorter test with an intermediate load might be enough for the intended purpose, i.e. a couple of non-critical years on a specific boat.

As Chairman Mao said, "Black cat, white cat, all same, catch mice."
 
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