Battery charging

[1meterstick]

I have a 2003 50 hp 2 stroke Yahmaha. I have a *****ing motor mounted at the front of the boat with a stand alone deep cycle battery. I would like to charge that battery while running the engine. Is it acceptable to charge this battery using a switch and wiring so that I can select to charge either the deep cycle or the starting battery. I have had a friend tell me he was advised against this using a similar hp Mercury.

Thanks

[rodbolt17]

can it be done?
yes.
would I do it?
no.
the charging system on that engine is rather small.
unless your running 5 or 6 hours the output wont be enough to make much difference.

[1meterstick]

Battery Charging

Thanks for the info.

If the charging system keeps the starting motor charged, wouldn't it do the same for the *****ing motor battery?

[rodbolt17]

lets compare the current draw from the battery when the motor is running.
then lets look at the current draw a *****ing motor uses when running.
now lets look at the total charging system output.
see what I am saying?
basically other than power for the tach/gauge package, that motor requires NO current from the battery to run.
the ign is self powered.
even without the regulator there would be no issues other than the prime start system would not work.
thats why there is normal,emergency and off positions.
my guess is your *****ing moter draws a few more amps than the 50 HP.