I have been searching on info all over the place and I'm not coming up with much help. I can't resort to grid power for charging so alot of advice doesn't work for me.
Here is my situation.
I'm off grid, to get these batteries to the grid power requires a car ride. I have 4, 400ah/20hr 6v Rolls Deep Cycle batteries that were given to me free 2 years ago by a neighbor. They leaked from the top and were not holding a charge well when I got them for free. I've since been using them as my sole power source. Knowing they were free and going to be replaced 'soon' I've used the hell out of them and have no actively neglected them, But they have suffered some pretty major abuse.
I only have a 250watt mppt controller and one 200watt 24v panel charging them. (I know its not enough) I have a diesel/veggie generator that puts out 2.5kw that I run a couple hours a day to dump more power in and to run my heavy power devices. Of course I keep adding more loads to the system but total daily draw is still 1-1.5kw total if that. I am using a Xantrex 1750 mod sine inverter.
I have been using a 50amp 12v charger that was only 100$ from tractor supply to dump power into them when the generator is running.
I have just found out recently that my complete RE system upgrade isn't coming anytime soon so I'm in damage control. I may have to limp by with these batteries another 8 months or more!
Its a completely make-shift cobbled together system that I built for remarkably little money, but I have to get aggressive because I think the batteries are really on theyre way out.
Before hooking them up last year I took them to town to a friends place and charged them with a automatic charger @10 amps for 3 days. They seemed to bounce back to life. They held steady at 12.7V even after running a electrolyzer drawing 35amps for 20 minutes. Since then they have been slowly getting weaker and weaker.
Infact I cannot get them to hold above 12.1v no matter how long I charge them with the generator. Even if I blitz them with 50amps for 3 hours, then second the generator is off even just running a laptop and 13w light they fall off to 11.9-11.7v.
Fearing that they are on the verge of completely dying I'm not sure what to do. I suspect the lack of reaching 100% SOC 'ever' combined with frequently setting at or below 12v is quickly coating the plates with sulfation and that with-in a couple months they won't even run a laptop for a night anymore.
I can run the generator for extended periods of time, but I've been trying to over charge them (even at 50amps, they never read above 12.7v during charging with no loads). But it has no impact.
I do not have a hydrometer, and perhaps my 12v charger is on the fritz or does not like the generator power even though everything else likes it just fine, even things that hate the mod sine wave inverter.
What else can i do? they are full of water of course.
Thanks so much, This is going to be an adventure!