Generator from a trolling motor

[jrx3]

Is it possible or reasonable to make a generator out of a Motor Guide trolling motor?

My question probably reveals my lack of knowledge about generators,but, if this is a reasonable thing to do how do I find out how to go about it?  I wish to charge two 12v batteries on my sailboat by towing or mounting a rotor on the boat.

Some people call me odd, others, the more honest ones, just call me crazy. The boat is an 8ft. Bolger Brick modified to be a camp cruiser. The electric needs are small, but for extended cruising I would like to be able to charge the batteries.

Can it be done??  

Thanks in advance for the information.

Yours jrx3

[Chagrin]

I'd assume it's a permanent magnet motor so it should work, but I think you'd need to replace the propeller to a design more tailored for generating power. It'd certainly be a lot of retrofit and leave you with a trolling motor unfit for it's original purpose.

Could be wrong though -- just try dragging it in the water, unconnected from the batteries, and hook a meter up to its battery clamps. You'd also need the motor in the "on / full speed" position, assumedly.

[Norm]

    A small prop made from plastic pipe with a

long shaft....connected to an Amtek motor?

    Would maybe have to be such that your average

speed would spin it at about 500-700 rpm ...

maybe someone here could do the number crunching

                    ( :>) Norm.

[scottsAI]

Power for a sail boat can be topped off with a small wind generator. 10 watts or so, keeps the blades small. Mounted on the top of the mast. Several can be used.

The source of power is the wind, the towed generator is much less efficient. The towed gen will slow you down. It takes it's power from your sail.

This is what my Dad does. Small solar panel is nice to.

Happy sailing!

[jrx3]

Thanks all for the suggestions.  Do you have any ideas on an  inexpensive  10watt wind gen.

[scottsAI]

Link will give you an idea. don't know where you are:-)

http://www.unlimited-power.co.uk/Aerogen_wind_turbines.html

http://www.4lots.com/browseproducts/Rutland-12V-Regulator.html

http://www.ampair.com/homepages/index.php?module=pagemaster&PAGE_user_op=view_page&PAGE_id=4
&MMN_position=8:8

Looks like something you could build your self. For much less.

Just don't make it so big it tips your boat over! Or hits your sail:-)

Have fun.

[Nando]

jrx3:

Yes you can do it, BUT you need to change the propeller with the highest TSR possible, with 10 knots ( about 11 MPH) about ( 4.9 m/s) with a TSR of 6 and 24 inch (24 *0.254 = 0.61 meter diameter) propeller the RPM would be around : 4.9 * 6 = 29.4 meters of revolution, so 29.4 /(PI * D) = 29.4 /(3.14 * 0.61)= 29.4/1.91 = 15.4 Rev/sec, 15.4 Rev/sec *60 sec = 924 RPM.

So get a 36 Volts Trolling motor that should run as a motor around 600 RPM if it is designed for higher RPM, then a higher TSR propeller and reduce the diameter, reducing its power output, 20 inches the RPM would be 924 * 24/20 = 1110 RPM THIS IS WITH THE SAME 6 TSR.

This is a tryout because there is not good data on Trolling motors and the highest voltage to take in consideration the RPM of the motor as motor, read the voltage and you may need a charger controller like the Xantrex C40, though even a regular DC/DC converter may do the job, like a a 28 volt to 14 Volts converter, the input make take around 42 easily and charge a 12 volts battery bank.

A standard generator designed for either boat trailing or wind driven runs around 800 to 1000 dollars for a much less than 500 watts system.

Regards

Nando

[tecker]

  I don't think it can do you a lot of good there the brushes will get hot and the power that you get will not match a small prop and a larger prop will be to much for the brushes .I ve messed a round with a lot of brus motor convertoins and they all

suck . They just don't seem to drive a load very well . The cog is mean also.

[deerslayer660]

   bioelectfier mike said a coupble years ago on a post that he did this on his sail boat. all he said he did was to install a diode in the pos wire of the trolling motor to stop the battery from suppling power to motor than he just durg it through the water chep enough to try install diode< about a buck> and put a volt meter on the battery if voltage rises your charging some  george

[cdg378]

It's being done, most I have seen are fully submersable units that are thrown in the water and pulled behind the boat.

Some claim that small units with paddle wheels work well also to trickle charge batteries.

I am currently working on some designs for my 40 footer for wind only, I keep my boat on lake st. clair and you can bet on winds from about 9 am to 9 pm everyday even in the marina.

They are savonious designs and I plan on having 10 or more (20 is not out of the question) simply built but good looking units on the upper bulkhead, they will be clear plexiglass rotors about 2 feet high. Just experimenting with coils and magnets trying to get it right, the goal is at least an amp per unit, the clear plexi makes them very difficult to see.

My personal opinion is work with the wind, there is plenty of it out on the lake at most times and it won't drag the vessel down too much, besides you are then generating power even when not moving through the water.

Also working with ni-cd's for lighting with white led's and small panels placed near the ni-cd's, very promising, right now on a typical evening I pull down about 40 amps in lighting just for the main salon mood lights and galley with pathway lighting. Solar, ni-cd's and led's are the way to go for alot of your lighting.

[nothing to lose]

"the brushes will get hot "

Water cool them?  

[nothing to lose]

I think I agree that wind would be the best thing instead of a tow unit.

 If your using a sail to power your boat, would adding a small unit over head possibly add to your speed? Make it so that the force of the wind driving the gennie is also pushing you ahead like the sails do. Just more area to catch the wind?

 A tow behind will slow you down instead. If burning feul to drive the boat with an engine your fighting that power by dragging anything. Again it might be possable that an over ahead wind unit could be adding alittle driving force at times if the wind is from the right direction. A tail wind could be a nice thing in many ways, and a head wind should not be that bad if the unit is small.

Now I can see the advantage of a tow unit if you may be anchored in strong currants near banks of tall trees like a river area then a tow type unit might be good. Powered while parked and the trees might create problems for a wind unit.

 I am thinking of building a house boat type vessle, something odd that's a cruiser and also liveable for the summer. Since I am planning some river use as well as large lakes I plan to use both wind and water power for the gennie and also as the boats drive. Gas engine for backup power to drive the boat and manuvering tight areas.

For river cruising in strong currants I am thinking a drop down system to catch the currants and push the boat ahead. I mean the wind changes anyway it wants at anytime, but the currant always flows forward basically. Unless of course I am trying to go upstream.

 This is also one of the reasons I am working on other things like producing hydrogen.

I'll have plenty of water, and it's alot easier and safer to carry large chunks of aluminum than it is 100 gals of gasoline. Then just make the feul as I want to drive, no feuls stored in a volital state while parked for days in one spot.

[jrx3]

I would like to thank all of you for the comments so far and encourage more.  I am moving toward wind as suggested by some of you. My trolling motor question came from the fact that I have one that I don't use.  I was thinking maybe I could use it some way. Sealed motor, weather proof. Maybe I'll try it in the air.  Well thanks for all the ideas.  jrx3

[mathis]

have a look at    ampair.com micro hydro

they are offering a  100 watt submersable propeller for charging batteries