Possibly Trojan T105's?
-If outside storage with Sun. Top off the water, add a dash of mineral oil, and let the solar handle the maintenance.
-If outside, or snow covered area of storage. Turn off the controller. If you can, pull the batteries and bring them with you and maintain via a Battery Tender or Battery Minder like device. If not possible. Then full charge them. And disconnect the Negative cable. (That is a long period of time. And Wet Cells (T-105's), will not enjoy that long of a period. AGM's will handle that period better, due to lower discharge rates, but also not like it too much.)
If it is the later, and inside. Can you possibly visit every two months and bring a generator to charge the batteries? Even it not topping off (ALWAYS PREFERRED), some charge is better the no charge.)
When brought of storage, if not maintained via solar. Bring the batteries back to full charge. Do a Load Test, and if they seem diminished. Fully charge them again, and do a Equalizing Run. (Over the years, this will reduce total life on the batteries. But, will hopefully get them back to closer to normal levels...)
And I will follow, as I may not fully understood your concern
Best to you and all,