Thanks for all the replies, I know it sounds like a odd situation so I will explain. I have to store the boat at a storage unit so I cannot plug it in to charge. I fish Flathead lake in Montana for lake trout so its a very large lake and I primarily vertical jig so I am on spot lock a lot. the storage unit is only a few minutes from he launch so if I run the generator between the storage unit and the launch it wont get much time. The run from the launch to various fishing spots in any where from 10-30 minutes so that is my best bet to get some charge on the trolling motor batteries. I looked into the charging systems that will run off the main engine but at least in 2021 when I bought the boat they were all a few years out on back order for what ever reason. I just figure getting a generator and running it when I can will keep the batteries mostly charged.