usually to be on the safe side we would recommend a larger Ah lithium for a 24v system just incase you want to fish a 16 hour day on the trolling motor. I dont have any customers currently running 50s, I also sale K2 energy and they always recommend higher ah. no one wants to spend that much and not get what the need to fit there fishing habits so most are hesitant to try, I get ask about this a lot and I could never recommend it with out knowing my self they would hold up. I do have extra 50s just sitting in the shop and im considering having a local with a 80lb ultrex test them in a long tournament day but feedback from more guys running this setup would be a big help to everyone and all brands. there are a lot of batteries to choose from now and I recommend getting what ever brand and size of Ah that best suits your way of fishing and your equipment at what ever the cost, they are all a big investment so make the right choice and enjoy all the benefits Lithium has to offer