"Rudy" wrote in
news:gzyek.98114$gc5.7380@pd7urf2no:

The pontoon boat I bought (haven't picked it up yet) has a single 12V
Interstate battery and a 60 HP "Tracker" by Mercury O/B
It has an automotive type CD player/radio and a 12V "cigarette
lighter" outlet.
Has anyone ever tried to run an inverter off such a set-up ? Nothing
too big, maybe 400 watts

I had never considered an O/B motor as having a significant electrical
OUTPUT but I guess it must be enough to keep the battery charged.
Also, I'm wondering if the boat is stationary at night with the nav
lites on and also the CD player, (O/B not running) how long the
battery would last before it might fail to start the O/B ?





Do the arithmetic....

400 watts divided by 13.5 volts = about 30A.

Let's say the battery is a 130AH deep cycle/starting boat battery. You
shouldn't discharge it below 50% or you'll ruin it very soon so you have
65 ampere-hours of usable power.

65AH divided by 30A is a little over two hours at 400 W, 4 hours at
200W, 8 hours at 100W.

Outboard motors were never designed to charge deep cycle batteries, only
to recharge what little cranking the outboard uses out of a starting
battery. The charger consists of some coils in the stator the magnets
in the flywheel rotate around and your little 60hp Tracker is no
different.

Direct from Mercury:
"Using an outboard to charge two batteries is only effective if the
outboard charging system is capable of delivering more than 15 to 20
amps. One point to remember: most systems are rated at wide-open
throttle and charge substantially lower amounts at slower engine speeds.
"

This is caused by the speed of the magnets on the flywheel.

You didn't tell us what year/model is good enough to look up the full
power ampere output of its little charger circuit.

It won't put out anywhere near 400 watts!

To recharge the battery properly from 50% down takes about 10-12 hours
of charging.....not 500A for 30 minutes...charging batteries is a SLOW
process, no matter what boaters tell you they can do.