Wet cell battery maintenance

Once a month or so I check the levels. I added a fill system to mine so all I do is charge, then use the fill system to top them off.

I always maintained electrolyte level -between- the top of the plates and the cell fill cylinder.

It is sooooooooooo easy to check the inside of the cells during max charge rate and see just how vigorous (or not) bubbling is. Proper intensity of electrolyte bubbling does not mean a roiling boil. It means 2-3 small bubbles per second. Hydrogen and oxygen atoms produced by electrolysis not heat.

Correct determination of sufficient battery charge is determined solely by the density of electrolyte, not degree of electrolysis. Specific density of electrolyte. Antimony migration can increase electrolysis 500+% A positive indicator of end-of-life cycle.

Cold and low charge, battery fluid level will be lower than when warm and charged
Check before charging make sure plates are covered
Topping off fluid should be done when batteries are charged
Should be right below the little slot in cell opening

My converter didn't do it's normal job in maintaining a charged battery. It overcharged them and I was adding water a couple times a year. Now that I disconnect (switch) the batteries once charged, I haven't added water in a few years. But I do check them a couple times a season. I keep my water level about an eighth of an inch below the filler hole edge.