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Micro hydro-electric generator help

IATSB

May 28, 2019
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I’m new to the forum, and very inexperienced in the field of electrical engineering (wishing I chose electrical engineering over biology). I am going on a wilderness fishing trip in northern Canada, and would like to take my fish finder/GPS. The problem is it pulls 1.41 amps (maximum brightness, etc.), and due to weight restrictions, I can only take 2 8 amp-hour batteries along. There is no electricity where I’m going, and I need a way to charge them. I have a small solar panel, but at peak efficiency (and no resistance loss) it would still charge too slowly to be of use. I’ve come up with the idea of a small hydro-electric generator that can be towed along/beside the boat instead. The only generators I’ve found that are suitable (and not outrageously expensive or heavy), produce 10 watts of power, but vary between 10v and 80v with the flow of water through the turbine. What parts would I need to assemble to be able to charge an 8 amp-hour 12v lead acid battery using this generator? I can work out the towing/generating assembly, but don’t know where to begin in the electronics department besides including a blocking diode. Also, would a second inline generator increase the charge rate when wired in parallel? or would it provide too much current and damage the battery? Any help will be much appreciated!
 

Bluejets

Oct 5, 2014
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If you can couple this mechanical energy to drive a dc motor or alternator seems like an option.
Perhaps a belt drive, or rubber wheel that rides on the flywheel?
My thoughts were that many outboards have an intergrated battery charger.
 

Audioguru

Sep 24, 2016
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A hydro-electric generator uses the boat's power to spin it. So whatever powers the boat will need extra power to spin the generator.
The same if you think a windmill will produce charging current. It produces drag than needs extra power from something to overcome it.
 

IATSB

May 28, 2019
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The idea is to have a small generator to tow beside/behind the boat, which will be powered by a small gasoline outboard. The only electricity the outboard generates is from the tiny magneto in the flywheel. I've already found a generator that will work (for $16) and weighs less than 1lb. I can figure out the towing setup/water intake, but don't know what I need between the generator and the battery to make it function electronically. I could spend hundreds of dollars on a new, less functional fish finder I'll probably never use again, or a big solar setup that won't work well when it's cloudy, and won't fit in the boat, and would have to be monitored in case of rain, which happens 2 or 3 times a day up there. I know I need a blocking diode, but I don't know how to regulate the voltage, or if I even need to. The description says it will produce 10 watts at between 10 and 80v depending on the water flow.
 

Bluejets

Oct 5, 2014
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Seems you are determined to go with the "water wheel" regardless of any other suggestion.

Tapping the resources of the engine would be the best alternative all round.

You already have a magneto and adding a "lighting coil" by some competent person would not be all that difficult. As I said, there may already be one there , depends on your outboard engine age etc.

You're lucky you are not "dragging your potential generator" in Aus.
Would be just the kind of thing a whopping great croc would find interesting. :) :)
 
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IATSB

May 28, 2019
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Seems you are determined to go with the "water wheel" regardless of any other suggestion.

Tapping the resources of the engine would be the best alternative all round.

You already have a magneto and adding a "lighting coil" by some competent person would not be all that difficult. As I said, there may already be one there , depends on your outboard engine age etc.

You're lucky you are not "dragging your potential generator" in Aus.
Would be just the kind of thing a whopping great croc would find interesting. :) :)
That sounds exactly like the kind of thing a croc might try munching on.
I agree using the motor would be the most efficient and effective, but we are flown to the lake and dropped off. I have no access to the boats or motors until I arrive, and they probably wouldn't appreciate me modifying them. If I were taking my own boat, I would just take the battery I currently use, which would run the fish finder for 100+ hours continuously. The generator also has to fit in a suitcase, along with all of my clothes and a portion of my fishing tackle.
A solar panel is cost prohibitive, and limited in versatility in the environment I'm traveling to. A wind generator seems like a poor choice in a small boat with 2 fishermen. I can't modify or fit something to a motor that doesn't belong to me/ I don't have access to. And we're limited to 100lbs per person including gear, clothing, and food, so a larger battery is impractical. That's why I'm stuck on a small, cheap, hydro generator. I also leave on this trip June 7th, so am pressed for time. I don't have the knowledge to address the electrical system involved. I can physically assemble whatever I need to (aside from building boards and fine soldering etc.), but don't know what components I need. That's what I need help with.
I do truly appreciate the advice, and investing your time to help a stranger.
 

davenn

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Sep 5, 2009
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or a big solar setup that won't work well when it's cloudy, and won't fit in the boat, and would have to be monitored in case of rain


you obviously didn't read my post or link !
 

davenn

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And we're limited to 100lbs per person including gear, clothing, and food, so a larger battery is impractical. That's why I'm stuck on a small, cheap, hydro generator. I also leave on this trip June 7th, so am pressed for time. I don't have the knowledge to address the electrical system involved. I can physically assemble whatever I need to (aside from building boards and fine soldering etc.), but don't know what components I need. That's what I need help with.
I do truly appreciate the advice, and investing your time to help a stranger.


seems you are not really :(
 

Tha fios agaibh

Aug 11, 2014
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Great thing about the wilderness is, you can use a compass and a map and find fish even without a fish finder.

I imagine it cumbersome to hold a generator off the side of the boat. Especially for the time required to get the battery to charge.

If you want to try, I might try a circuit similar to this.
2019-05-29 07.32.44.jpg

I left out a blocking diode to minimize voltage drop with the assumption that current will be monitored on the ammeter. When done charging, you disconnect battery leads.
 

Tha fios agaibh

Aug 11, 2014
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you obviously didn't read my post or link !
I think it's great option. Even partly cloudy you'd get more power than the water wheel generator. Only problem is it's cumbersome and can't be used on the boat.

But you could have two batteries; One charging back at the cabin, and another while fishing.
 

Tha fios agaibh

Aug 11, 2014
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no it isn't and of course it could be used on a boat .... dunno what you were reading ?? ;) ;)
I disagree. A "wilderness fishing trip" usually has small boats like this, or smaller.
Screenshot_2019-05-30-03-20-57-1.png

If you ever been fishing, you'd know space is very limited with two men and their gear.

Just try changing out a lure in a rocking boat, or quickly trying to reach for the net with a solar panel smack in the way.

Then try to tell me with a straight face it isn't cumbersome.
 

BobK

Jan 5, 2010
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I agree that using a solar panel in a small boat would not be ideal.

On the other hand, the dragged turbine only produces power when the boat is moving. How much of the time is spent moving? I am not a fisherman, but when I see people fishing on the lake, they are mostly standing still or drifting with the currents.

Bob
 
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