I still use semi or box truck type batteries, whatever brand my local International dealer has in stock is what I use. I have a friend who works for the electric company in my area as a diesel mechanic to keep their fleet of trucks going. Every two years they MUST replace the batteries in those trucks, so he gets the used ones for nothing. He asks me all the time if I need any, that is what I use for my LQ trailer as they are the bolt-on type connectors that are used on marine style batteries.