Marine battery charging from outboard motor?

Question

Is it possible to charge my marine battery while my 15 hp outboard engine is running? What do I need to do?

Answer 1

If your 15hp motor doesn't have electric start, the answer is an absolute NO. You would spend such a fortune buying enough OEM parts to convert a pull-start to electric start (plus internal generator) that you could buy a new motor that already has electric start - and have a ton of money leftover.

If your motor has electric start, the answer is YES - but read on....

This would only work if you used your marine battery (or a larger "starting" battery) as the single source to start the motor and run everything else that you're intending to power. This is because, even with an expensive dual-battery isolator, the motor's lame little internal generator only has the capacity to charge a relatively small battery (like that used to start a motorcycle or ATV) and could not charge two batteries (or even a large single battery) with anything more than an insignificant trickle.

Even using a single large battery, the motor's relatively small generator probably wouldn't supply enough current to actually charge the battery if you were running other electrical equipment at the same time - e.g. the rate of discharge from other equipment running would be higher than the rate of charge from the motor. So, you would only be prolonging the time it takes to run the battery down when other equipment was being used.

You will also have another problem because a "deep cycle" marine battery and a "starting" battery are two different animals. The marine battery is designed to supply lower levels of current (amps) for a long period of time (for lights, trolling motors, etc.) and continue to slowly drop in available voltage to keep things working for quite a while. On the other hand, a "starting" battery is designed to supply a very high current (needed for starting) for a short period of time; but, unless it's receiving a relatively high charge rate from a generator or alternator, it doesn't do well with long-term lower current drain before suddenly cascading off in voltage and going dead.

Bottom line is that you'd be better off using a deep-cycle marine battery because you could always pull-start a 15hp motor if the battery got too low to crank the engine. In either case, you would still have to rely very heavily on being able to frequently use an external (plug-in) AC battery charger to actually bring the battery up to full charge. Even with nothing else sucking power from the battery, you'd have to putt halfway around the planet at full throttle before the small generator in a small motor would bring a large battery up to full charge.

Hope this helps

Answer 2

15 Horsepower Outboard Motor

Answer 3

You can hook a starter motor up but, the battery won't charge from the motor, unless it is set up for that. You'll need shore line power to a trickle charger to charge the battery, I've seen sail boats set up with 9.9's (H.P. outboards) that way, they used the power tilt switch on the control box as the ignition key.

Answer 4

15 Horsepower Boat Motor

Answer 5

Some 15hp have a plug in on the front of the eng without electrice start if not an no ele than no.I put a solar panel in my John boat good for bilge pump.

Answer 6

1

Answer 7

does the positive lead from the motor to the battery need a fuse

Answer 8

you need a generator to charge your battery when running. possible to retrofit, but may not be worth it if it's an older motor.

Answer 9

As long as it has electrical start It would maby need some wiring

Answer 10

I think its impractical for the amount you would pay to get it set up.
Good Luck