O great, Thank you so much already, it gives me a good confidence boost to what to look for.
A yes for the trolling motor itself I think at maximum/full throttle it will drain 43amps but this will be much lower most of the time. :)
After a gamble I got 8 second hannd nissan leaf modules of 7.4volts 66Ah. Each module has 4 cells (2 in series and 2 in parallel).
I would like to put 7 modules in series in order to use a 48v trolling motor.
Quite new at all of this I am searching for a BMS but got a little bit lost...