About 8-ish years ago I designed and built my off grid solar system based on info I have learned in this forum. My system is still going strong except my batteries are showing signs of loosing capacity. In a cold weather, as it is right now here in Canada, they operate around 50-60%. I would say it is normal for the age. My concern is that they may get frozen and crack due to diminished capacity. They will probably survive another summer and run my fridge, lights, TV and Internet but it is time to start thinking replacing them with Lithium. I will be browsing this forum again in hope to pick on other people experiences. Classic 150 still going strong.
THANK YOU ALL and marry Christmas and wonderful holidays to all!
You can use lithium if you build an insulated box around your batteries . I don't know how large you system is or how much storage you need. But compared to lead acid for the same amount of usable AH they are physically smaller. You can take safely take 80% of their capacity out of them with no harm.
I built an insulated box around my batteries using 2x2 and some poly iso type insulation board. I have a small heater inside the box using an inkbird temperature controller that has a probe that goes inside the box.
There are also heated batteries available , though some of those don't turn on until the batteries are below freezing , and then turn on the heat before charging ( usually using available sunlight ).
Enjoy the winter - it has been pretty mild here in Wisconsin - all in all even though it is of course cold outside.
Larry