Installed after boiling water and damaging some batteries. I left my mobile home permanently connected to the land network during the interior work and the batteries drained prematurely. They were old batteries. After installing two new deep cycle lead-acid batteries, I kept adding water about every third week. After installing this product I monitored the water closely and it's holding up like a rock. Wonderful! I've also noticed that my new batteries hold a charge much better and last longer.