How long would you be able to pull cranks with a 36 volt minn kota ultera on a average day. Group 31 batteries on a 20 ft champion fish hunter. I have a 36 on my pontoon that I am thinking about putting on the boat for crappie fest. I was given a 4 hp Yamaha that needs work and not sure if I can get it running in time. How long do you normally pull during a day of fishing. Got no room for golf cart batteries or the money. Thanks