3 50 amp batteries won’t last that long running the trolling motor continuously for pulling cranks. Been following the lithium posts for a couple of years on bbc forum. You might ask this question here. Electrical/Wiring/Trolling Motors
I know there is a few times using my 100 amp lithiums pulling cranks in winds and 1-3 ft chop for 6-7 hrs,,they have 52-54% power left in them but I have the 2 in parallel and use a 12 v. Powerdrive v2 MK TM. With lithiums,,,,you really don’t want to take them down to 10% left in them as it has a tendency to decrease life expectancy. There has been a lot of questions on how long 50 amp batteries will last you in bbc forum and for the walleye guys,,crappie guys and Striper guys on that forum,,,I think all of them went to 100 amp regardless of the TM being a 12 volt, 24 volt or 36 volt. One other thing they mention you might consider which is sometimes brought up…more users think going to 2 or 3 batteries vs one 24 volt or one single 36 volt would decrease expenses and get you out of a possible jam if having to replace a battery in case for some reason one went bad if you were on the road. However,,,I have not seen anybody post having issues fishing with one going bad to creat this situation with lithium batteries. It happens moreso with wet cell batteries.