Rainy Day Project

[burroak]

While sitting in the garage as a steady rain is beating down in SE Wi, I'm looking at a small electric trolling motor and mulling over the idea of making a battery charger out of it. Some small private airplanes have a propeller driven generator attached to the wing strut or elsewhere to provide electricity. Is it possible to do the same thing for boats? And what would be involved? I haven't searched the web yet; thought I'd toss it out here first.

 

[byacey]

Re: Rainy Day Project

I doubt that it would make an efficient charger and create a considerable amount of drag. I have never looked at one closely, but if it doesn't have a permanent magnet field, you will also need some way to excite the field windings to get it to start charging. Do you think you could row the boat fast enough to charge your starting battery?

 

[Silvertip]

Re: Rainy Day Project

You are flogging a dead horse. That process would not generate enough elctricity to keep even the start battery charged, not to mention the amount of drag it creates. Remember, perpetual motion has not been invented yet. If you want to generate electricity using a generator, it takes power to spin it. That power is the result of drag. That drag represents power loss. That represents a very inefficient way to generate power. Small planes have very small batteries and very low power draw so the little generator represents very little drag. A boat operates in water that presents much more drag than air.

 

[burroak]

Re: Rainy Day Project

You are flogging a dead horse. That process would not generate enough elctricity to keep even the start battery charged, not to mention the amount of drag it creates. Remember, perpetual motion has not been invented yet. If you want to generate electricity using a generator, it takes power to spin it. That power is the result of drag. That drag represents power loss. That represents a very inefficient way to generate power. Small planes have very small batteries and very low power draw so the little generator represents very little drag. A boat operates in water that presents much more drag than air.

I was intending on flogging that horse with a 135hp Evinrude.

You may very well be right, you can tell it's a slow rainy day.

byacey has a point regarding the permanent magnet situation. As I said, I haven't investigated the physics at all. It's just that outboards don't have much of a charging capacity in and of themselves and I have long high speed runs fishing for salmon in Lake Michigan; figured to juice up the accessory battery on the way out and in.

 

[QuadManiac]

Re: Rainy Day Project

Add a pulley and v-belt to the flywheel and an automotive alternator, lol. Motor driven generators can be pretty efficient.

You could probably build a water driven generator that would be reasonably efficent... maybe in the 30-50% regime if you're very lucky, with a LOT of effort and expense. But you're not going to get anywhere near there with a trolling prop and motor.

 

[tashasdaddy]

Re: Rainy Day Project

why not mount a sail boat wind driven generator on the cowling of the motor. then it would charge while running the boat, and towing to the ramp. dead battery just hook up the boat and go for a 100 mile drive.

 

[burroak]

Re: Rainy Day Project

why not mount a sail boat wind driven generator on the cowling of the motor. then it would charge while running the boat, and towing to the ramp. dead battery just hook up the boat and go for a 100 mile drive.

Dang! (smack on the forehead) now I know why you are Moderator.