I run Optima Blue Tops.D31M for cranking and electronics. I run an HDS-5, 7, and 8 with SS all day (4-5 hrs. at a stretch) and it still cranks my 150 Opti without breathing hard. D27M for 24V MG Tour Digital 82#. More than enough battery to run my MG all day. I dont just stay on the TM, but do fish a lot of current, and in open water, and move 200-300 yards on high at times. They charge back to full in under 4 hours.