I am using 3 Optima D34M dual purpose group 34s. BUT, I run an EFI motor, so you need more cranking on that Opti/DFI engines. However, for trolling motor use, they are good. For me, they are the Cats meow!96 Eyra/12 Mercury 175 Pro XS with 2015 single axle trailer2017 Victory Gunner