I am installing a Minn Kota trolling motor (i-pilot) 12v, a Garmin 93SV fish finder, and a Garmin Livescope on my pontoon boat. I already have a small Humminbird fishfinder at the back of the boat powered by one battery. My question is how do I wire up the three items listed above? Do I need an extra battery??

I would install the electronics on the battery you have, then install a second battery for the trolling motor. You want to keep your electronics separate from your trolling motor to reduce interference.

That's what I was thinking. Thanks for your input.

Ditto on everything to the boat's main (starting battery) except for the trolling motor. You want a large deep cycle battery for the trolling motor, with a Group 27 or Group 31 size for that deep cycle battery. If you have access to Sam's Club, they sell a good deep cycle battery in Group size 31 for $100 + fees/tax. You'll also need an appropriate circuit breaker and possibly some 6 gauge wire, depending on where you locate the battery. Your trolling motor will draw a LOT of amps, so operating without a breaker is not advised; it can be dangerous, start a fire if something goes wrong. Post which pound thrust motor you have and I can tell you the breaker size you need.

run a 12ga. wire for the garmins, upgrade the start battery to a combination in at least a grp 27 size if it is not already.

use a 10a fuse at the battery and the fuse that came with the garmins at the front connection.