Incidentally, last winter when the Echo refused to start on a cold day early in the season, I made the executive decision to swap out the battery for a more expensive, but hopefully better performing glass mat battery - one that should be much better able to handle extreme low temperatures, as well as not requiring water.
In any case, for our cabin, we are utilitizing the very old, very proven technology of FLA batteries, or "Flooded Lead Acid" - batteries that are essentially made up of thick plates of lead, submerged in sulphuric acid.
During the end of the absorption cycle, and throughout the equalization cycle of charging, the electrolyte (i.e. acid) begins to boil and churn inside the batteries. This has the effect of stirring up the liquid, helping to prevent sulphation, but it also causes evaporation of the water in the electrolyte. (I suppose it may technically be electrolysis - the water is broken down into hydrogen and oxygen, which then escape into the air?)
This has the overall effect of causing the acid levels in the batteries to be reduced and concentrated. There's nought to be done for it really, aside from purchasing much more expensive sealed batteries. Instead, one just has to do a routine maintenance chore of topping up the water levels from time to time with distilled water.
|The new bottle really helps!|
|But the floor makes an even bigger difference to this chore!|
I used to try to do this with a turkey baster, but over the summer found a purpose-built bottle for filling batteries at the local ToolTown store. This has helped greatly with the adding of water, which I try to do every month or two. I've not found it to be a hardship at all, although in winter it was less palatable than it is now. This year should be even easier now that I actually have a deck to stand on when I do this, rather than slogging through the snow to perch on the floor joists.