Ways To Charge Battery

[Owl-Mirror]

While there is wealth of information on this website, I too am seeking a way to charge my 12v Deep Cycle Marine Battery. I own a 1967 Johnson FD21 20hp Outboard Motor.
I am disabled & was unable to Pull-start the motor so, I had a mechanic convert it to an Electric Start. Apparently there is a Company in California which is producing OEM spec. Cast Brackets for the older Motors. Now, regarding the ability of charging the battery. My motor doesn't have the space needed under the cover to incorporate an Alternator so, my next recourse is using a battery charger. They Sell Solar chargers, Wind-driven chargers and I could run an extension cord from a small battery charger to the inside of my truck & plug it in the Alt. Elec. Source plug. Another option I was contemplating is designing a alternator which is driven by a propeller, lowered into the water. This would be similar to a Wind Generator but, using the water instead of wind. This way when you are under power or drifting down a River, the water would turn the prop. which in turn operates the alternator, which then charges the battery.
Either way, an outside battery charger is necessary.

 

[GA_Boater]

Moved this from an old inactive thread to one of your own. You can't post links to competitor websites, even by mangling the name, using DOT com, etc. This forum is an adjunct of iboats.com. a marine parts retailer.

As to your problem, The only viable way to charge the battery is with a home charger and install a backup battery. Solar, wind and the water windmill just won't do the trick. The costs involved would likely justify buying another motor that suits your needs better.

 

[Georgesalmon]

There are lots of towed alternators. Though I've only seen then used on sailboats. Might not work at higher motor boat speeds.

 

[MH Hawker]

get a motor that charges

 

[Silvertip]

The degree of charging ability must be considered based on the amount of current consumed during your outings. Just because you have "something" that produces electricity, it must produce "more" electricity than is consumed during any one outing. Otherwise you are in a losing situation and battery life and the ability to start the engine are diminished. Solar power requires a panel nearly the size of your boat to be of any use on a short term basis and then only when there is full sunlight. A towed generator would require something on the order of 4 - 5 amps and very long run times to add any amount of charge to a battery. Wind power is much like solar -- no wind, no power. Drifting down a river provides no power whatsoever because the current is carrying you so the prop, boat and water are all traveling at the same speed which is zero with respect to each other. If the boat was anchored, then yes, the current passing the propeller would provide some capability but again, output of such a generator is very little and certainly not sufficient to charge a deeply discharged battery. Your two most practical solutions for a single battery installation is to install the largest deep cycle battery you have room and budget for, and/or install a smart charger of 5 - 6 amp capacity or more and plug into shore power at the dock or at your home for a trailered boat. As an aside, you have not indicated what the electrical load is for this boat. That is what will determine what you actually need.