Hey everyone

i have a rookie question

My trolling motor batteries are finally starting to need some water after the first two
yeats of them not losing any...I check periodically and today I found that all three were getting a little low and the top of the cell was out of the electrolyte but not fins. I have been researching and plan on filling each with distilled water to just cover them not all the way into fill neck...is there anything I’m missing? I really don’t want boil over in my pretty ranger

thanks