You will need either a 100 amp lead-acid battery which is very heavy or a 50 amp lithium. Your 30 ft lb thrust motor uses 30 amps/per hour at full power so the lithium really is a better choice. You will never run the motor at full power all day long.
But Tacbelt...who is using a trolling motor at WOT (wide open throttle) constantly ?
Nobody.
I have run my 30lb Minnkota, pushing my 12' Livingston, at "normal" trolling speed of 1.2-1.5mph for 4-5 hours MANY, MANY times before switching to my spare.(It's best to NOT run a deep-cycle down fully)
If in doubt of the consumption of your trolling motor, visit a Batteries Plus, they have the ability to measure the draw at various settings, so you can determine longevity of a particular amp/hr battery with your motor. I did that with an old Eska 12lb thrust, that I occasionally use on one of my Sea Eagle 285fpb's, when I am not going far or for long....it draws less than 3amps @ #3 speed(out of 5)... certainly the reason I can get a full day (6-8 hrs) with one battery.
Unless you are "racing" to the other end of the lake with only the trolling motor as propulsion, and then trolling extremely fast, you will be fine.
Unless of course, you have the mindset of "Tim, the Tool Man" and simply seek "more power"..... guess you can get that familiar "grunting sound" as you load that size 24 or 27 in your boat, huh ?.....lol.
If you want to reply, then
register here. Registration is free and your account is created instantly, so you can post right away.