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post #4 of Old 04-17-2014
Maine Sail
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Re: would you buy used AGMs?

Originally Posted by rmeador View Post
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.

-Maine Sail / CS-36T

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Last edited by Maine Sail; 04-17-2014 at 04:20 PM.
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