Looks like they have caps so need water. You'd pry off the NAPA logo'd cover and one one that says danger (I use a set of channel locks for this) and then fill with distilled water periodically. There is a kit you can buy that will replace those covers and make it easier to maintain. I'm not sure how much those cost.
2010 Winnebago Vista 32K with a 2013 Mini Cooper S Roadster toad.