Suggestion ... here's where a few extra bucks spent on 2 batteries ... a
starting battery (for starting) and a deep cycle battery (for trolling) ...
outweighs that one time that the outboard decides not to start first crank.
I use two batteries normally connected in parallel. When trolling, I
disconnect the deep cycle from the system and troll off it. When done
trolling, and after starting the engine, I reconnect them in parallel. So
.... except when trolling, I am using two batteries that charge as I go.

But to answer your question, it all depends. First, that 700 amps does not
figure in the calculation. It's the battery reserve capacity, the current
used (e.g. the trolling setting), whether the battery is fully charged to
begin with ... and on and on and on.

But if you have a pull cord, go for it.

"CCred68046" wrote in message
...
I need a recomendation for a bow mount trolling motor for an 18' aluminum
bass
boat. Boat has a 90 hp outboard motor. Would like to use one battery,
one of
the deepcycle/starting type (12v) for both motor and trolling motor. I
cant
help but notice almost everywhere I look has refurbished Minn Kotas for
sale.
Whats up with that? Are they junk? Why would so many be refurbs? ...
Anyway,
how long could I expect to run with a 50lb thrust motor before I would be
in
danger of not being able to start the outboard with a 700 amp battery?