Think I may have gotten lucky with my off grid battery bank. Was feeling a bit bummer that my 10 year old was failing and having to consider replacement. I had hoped that I'd get a few more years and in that time technology and prices might improve. Mine were pretty much top of the flooded lead acid line when I got them. A 10 year warranty wasn't too shabby at the time, but I did cringe a bit at over $800 each and I needed 12 for a 48 volt bank.
One of the newer hot technologies is Lithium (Tesla is one). We had the opportunity to check out a neighbor who just got some very recently. A very nice system put out by Sony, but near as I good figure a minimal system for me would be in the neighborhood of $40k, definitely not in my budget. So this week has been quite busy looking at alternatives while also discussing on the Outback Power forum. With a lot of help, we were able to determine that I really had 1 bad cell in 1 battery and hopefully I could recover the bank. Rule of thumb, batteries are not readily substitutable piecemeal as they perform best at a state of equilibrium. The installer that I was talking with about new batteries thought they may have some just like mine from a previous job, about 8 years old and kept on a maintainer. They did and this morning I picked one up at there shop. $200 vs $1600 for a new one.
Had it installed by 1230. Muscling a 315 lb battery in the middle of a bank was a challenge. Old one came out readily, new one took more finesse getting placed, but did it.
As soon as it was hooked up and system restarted I saw improvement
Here is battery on my truck
Plan was to use my tractor with forks to unload. Tractor wouldn't start. Luckily I have a hydraulic lift table.
This is my battery bank
Replacement battery is 3rd from left.
Feeling very good about how this worked.
Now to get my tractor running...