I have a 36V saltwater MK Terrova and went with Miller Tech. I am charging them with a 3 bank MK precision onboard. I had an issue where one of the batteries would drain to zero before the other two. I switched their position up on the charging banks and the problem followed the battery. I contacted MillerTech and they were fantastic. They sent a replacement to me next day. Since then everything has been great and I can troll all day with the waves or around 9 hours if I'm heading into or a combo of in and out of the waves. Boat is a Robalo R247 and is quite a heavy boat. I am just hoping the batteries last long enough to justify the expense, but as of now I am extremely happy and its been 3 years.