Good day all I have 12 of the above Batteries they were pulled from a solar system at our cottage. When I measured them in parallel I had a voltage of 3.9 V DC. I pulled them all apart so now their individual batteries I have an odyssey optimizer 50 amp single bank charger connected to one of the batteries. I tried to charge the battery it will not charge past 6.89 V. So does that mean the battery is toast or do I have to let it charge longer the optimizer said it was at 73% but stayed there for almost 8 hours. Any help would be great as I don’t want to scrap these if I can salvage them.
Click on the link for pics.

https://imgur.com/a/yN62qgJ