I am going to my boat tomorrow and I see what kind of regulator I used. My system is currently set up to charge AGM batteries, a group 24 and 27. When I use the panel on my M 15, I'll use a AGM U-1. Bert M 15, Zephyr ************** It's only a deal if it's where you want to go. Find your travel deal here. (http://information.travel.aol.com/deals?ncid=aoltrv00050000000047)