Building a trolling motor generator

[HydroCamper]

Take a look at the pictures to learn more about this project. The goal of the project was to build a portable hydropower system that could generate 20-30 watts of continous power to be used for remote roadside camping with an output of 110 volts. The project uses the smallest outboard trolling motor with a simple aluminum cage built around it. After a little experimentation it was found that the trolling motor worked much better running in reverse. The biggest problem with the project was with the low voltage the generator produced. Testing showed that it produced between 2 and 6.5 volts depending on the stream speed. Standard inverters require 12 Volts. To overcome this problem of difference of voltage 1.2 nickel metal hydrid batteries were hook in parallel to creat a total the required voltage. A mechanical mixer was built to switch the voltage from the trolling motor to a section of batter bank. I attempted to build a transformer that would boost the voltage but I could not find a design that would work, so I setteled on the mechanical switcher. The mechanical switcher has higher opperating efficiencies anyway. To power the mechanical swiches I used a gearbox from a wall timer for turning lights on and off. The disadvantage to this is that it requires the inverter to always be turned on. After getting everything together and doing some stream testing I found that power output of the trolling motor could be greatly increased by placing it in the best position. Just an inch of movement in a stream can make a big difference. I had planned to fasten the generator down by using stakes and lines to the cage, but found that placing rocks on the top of it worked just as well. How much water is needed? Enough to fill a 1 foot pipe that drops 6 inches or more. A one foot drop is really good boosting the power to 6.5 volts for some great charging. I have not tried it, but I suspect this design would work very good by placing in front of or behind a culvert pipe or culvert bridge. I am using a 400 watter inverter that can surge to 800 watts. I have ran a 650 watt drill off this system with success.

If you have any comments, suggestions, or questions I would love to hear from you.

Travis

[ignesandros]

Nice. You ran the drill at full speed just off the power produced by the motor? Have you considered a condensing funnel to increase internal water velocities? What's the motor's make/model?

-Andrew

[electrondady1]

thats a nice device. may i make one suggestion? simply, if you were to wire the extension cord into the geni you could eliminate the connection  and the proplems caused by it being submereged

[HydroCamper]

The brand name is MotorGuide. Its the smallest model at just 30lbs of thrust. I bought it at wallmart for less than 100 dollars. When I was looking around I found models that had output of 180 lbs of thrust. The power generation of those must be really good. I thought about doing a funnel, but after some stream testing I decided not to do it. For the most part a natural funnel can be created just by moving some stones around in the stream. A funnel will also cause the water current to turn it backwards. And for some odd reason, I find if the generator creates a damming effect it breaks away loose stone in front of it which cause them to ram into the blades with force. BECAREFUL WHEN PLACING THIS GENERATOR IN THE STREAM. ITS EASY TO SLIP ON THE WET ROCKS AND ALWAYS WEAR HEAVY GLOVES AND KEEP YOUR HANDS AWAY FROM THE BLADES.

[Nando]

TRAVIS:

Yes, the trolling needs to work in reverse because the blades are for power use and not for power harvesting.

First the blades are too small, you need blades with diameters at least 2 times the blades that you bought with the motor.

Second the angle of attack of the blades needs to be about one half to double the RPM.

You need to double the RPM to raise the voltage to 14 volts to charge the battery-- remember to place a Schottky power diode in series to avoid discharging the battery if the power(voltage) generated is lower.

THIS SETUP IF no ducting as shown below -- though the blades should be with lower angle of attack.

~~~~~~~~~~~~~

Third the Funnel should should be long enough to give a head, every foot will add about 0.433 psi and add around 1 watt per liter/sec that the generator see.

The Funnel diameter needs to be with a larger diameter than the blades diameter and the water available should fill the duct completely for maximum power.

Some have used collapse-able flexible plastic tubing, 12 inch diameter to generate around 1 or 1.5 meter head placing around 50 or so l/s to attain around 100 to 200 watts power out. ( the type used to connect the exit air of a dryer to the outside, but larger in diameter).

It takes around one hour of work to do the job if you have a good place.

Also, plastic heavy 10 or 20 mills thick rolls of tubing ( 10-12 inch diameter), to bring the water from higher up -- like the rolls of plastic to make bags for fruits and vegetables by THICK WALLS -- they are available -- I still have a roll of 8 inch diameter about 75 feet long.

Rings were made to open the mouth and the exit to attach to the Turbine -- careful installation to avoid rupture and making sure that not more than 2 meters head = 6.5 feet head.

Presently designed unit you have that have just 6.5 volts can be converted to generate 12 Volts to charge the battery -- what is your electronic experience -- to build circuits ?.

I can help you with the circuit.

Connect directly with me at nadno37-at-comcast-dot-net

Regards & Good Luck

Nando

[JeffG]

If I were to play around with a troller, what would be a recommended device, just to get the feel for such an application?  

[HydroCamper]

As a follow up to this posting I later added a funnel which greatly increased its power outout. This was made out of 1/4 plywood attached to a 5 gallon bucket. One end of the bucket was cut out to let the water pass through. Three adjustable ropes where added that ran back to one main rope which was usally tied to a tree or a large rock. Making slight adjustments in the angle of the bucket/motor increased power substaintially. Overall the project did not succeed. The main problem was that the prop had to run in reverse, which meant the strait edge of the blade cut through the water first. AS a result the slightest of debree (I am talking about things less than a quarter of an inch such as a piece of a leaf) would accumulate on the front edge of the blade dramatically cutting the efficiency. This would usally happen in less than a 1/2 hour. If someone could make a highly curved blade designed to run in reverse it might work. I attempted to fabricate one, but the efficency was no good.