Used Battery nearby...

BradKW · Jun 19, 2016

I'm not sure if buying a used battery is something I want to consider or not...but these just popped up on CL: https://keys.craigslist.org/bpo/5643844792.html

[font='Bitstream Vera Serif', 'Times New Roman', serif]Two Deka Solar Batteries 8G8DLTP for 1000$... not really what I had in mind, but perhaps a low offer might be worthwhile?[/font]

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SternWake · Jun 19, 2016

I'd pass.

Looks like the casing has done some big time flexing as if overcharged repeatedly.

Without performing a real capacity test it is really a crapshoot.

A real capacity test would be applying the 20 hour load precisely for 20 hours and seeing at what time it took voltage fall to 10.5v.

The load testers can't say if a battery will perform well in deep cycle service, only if it can start an engine.

Without a trusted history from a previous owner, used batteries are best avoided in my opinion. Too many nimrods who have no idea how to take care of a battery. Much more rare is the well treated battery finding itself up for sale.

AGMS in South Florida need their temperature compensation when charging performed more precisely. Standard absorption voltages at 95f ambient will cause an AGM to offgass. I have been very surprised just how much my low resistance AGm has been heating during absorption charging, exceeding 84F in low 70F ambients, and those Deka defender are a higher resistance AGM with more thermal mass.

Checking further I think those are Gel batteries, not AGM, making them even more susceptible to damage from imprecise recharging.

Pass.

jimindenver · Jun 19, 2016

Flexing and from the corrosion on the post, I'd say they were not well cared for. That's pretty pricy for used I'd think. For $200 more you can buy a new set of Lifelines.

highdesertranger · Jun 19, 2016

1k for 2 used batteries with no mention of any kind of warranty. I would pass. do they even make 8D deep cycles? highdesertranger

jimindenver · Jun 20, 2016

For a grand you can get 6 new 6v and then some.

SternWake · Jun 20, 2016

Mainesail's opinion is that 8D flooded/wet batteries are basically just thin plate starting batteries.

http://www.pbase.com/mainecruising/deep_cycle_battery

Actual Gel batteries are excellent deep cycle batteries, but they have very particular charge requirements and with South Florida temperatures I would suspect they have seen charging voltages higher than desirable at some point. This can cause voids in the gelled electrolyte and instant unrecoverable capacity loss.