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vidaliaman
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# Posted: 29 Sep 2014 09:38pm
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Hi all, i'm a newbie here, want to build a water wheel. I am thinking of using a car alternator or generator(looking for advice), how many parallel 12V batteries would a car alternator be able to charge running 24/7? do i worry about over charging?
sorry about my ignorance but i have to start somewhere and i am starting from scratch
thanks dave
michigan
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Don_P
Member
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# Posted: 29 Sep 2014 11:13pm - Edited by: Don_P
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I was curious, found some very basic math for an old time overshot wheel and plugged it into a calc. At low flow I could about run a light bulb 
http://www.timbertoolbox.com/Calcs/waterwheelHP.htm
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bldginsp
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# Posted: 29 Sep 2014 11:25pm
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Is it a big creek or a little crick? How large a wheel are you willing to make?
As far as charging goes, you need a charge controller matched to the voltage input and output. The solar guys can tell you more about that.
Any sized generator/alternator will ultimately charge any number of batteries, but, will the generator be able to replace the charge as fast as you use it? First thing to know with any battery system is- what are your power needs, how much will you use in a day? Then pick batteries capable of supplying that, then pick a power source capable of keeping up with your use.
Divert your creek so that all the water is applied to the drive wheel, make the biggest drive wheel you can, take pics and post them here!
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vidaliaman
Member
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# Posted: 30 Sep 2014 08:55am
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thanks for the prompt replies, just a little back ground, just bought land in the upper peninsula in michigan and will eventually exist off the grid, this is going to be a passion for me to learn, let's say 4 60watt light bulbs, tv and a refrigerator(5th wheel), i have plenty of time to experiment with this project however would like to start with a bicycle tire that i will turn into a waterwheel, will purchase(hopefully a low rmp alternator), then will determine what kind of output i will get, there are a lot of variables, like speed of stream and rpms of tire, once i have this built and determine how much out put the generator will produce i will tweak and grow from there, i assume with this wheel running 24/7(except winter) it should do the job keeping the batteries charged. With what i have described what kind of generator should i start with? part of the fun for me will be measuring output and working to improve output but for now i just want a basic setup even if it is just powering lights, thanks again for all your patients for this newbie
dave
michigan
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cman47c
Member
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# Posted: 30 Sep 2014 09:33am
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You would need a DC motor that generates its output current at a low RPM rate since your water wheel will turn rather slowly not totally unlike a homemade wind turbine generator. A 1800 RPM DC motor would not be good. You need something in the range of 200 RPM. When you turn a DC motor in reverse, it becomes a generator.
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vidaliaman
Member
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# Posted: 30 Sep 2014 12:10pm - Edited by: vidaliaman
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i have heard of people using treadmill motors, do they use this in reverse to generate juice? would that be considered a dc motor? not what i will use but just asking. does dc stand for direct current?
once again thanks for the patients
thanks for the great start!
dave
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groingo
Member
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# Posted: 30 Sep 2014 12:32pm - Edited by: groingo
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Before you begin you may want to check and see if the stream is listed as a game stream or creek (if it has fish) if so it may be protected and could be an issue but either way you may want to discretely check it out which can be done typically at the county level and be sure to get in writing...best to know before hand than after when you have made an investment of time and effort only to be looking at possible fines and headaches on top of things.
For example my stream has a 200 foot setback requirement and is a class 2 game creek but in winter my little creek typically 12 foot wide by 12 inches deep running 7 cfs can grow to over 200 feet wide and 8 foot deep pushing 700 cfs which made it a problem in itself let alone the regs....thankfully I went solar and have zero regrets.
For good flow information on streams you can use the USGS stream flow website which has been a great tool.
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vidaliaman
Member
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# Posted: 30 Sep 2014 01:02pm
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thanks for the info, will also study solar
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MtnDon
Member
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# Posted: 30 Sep 2014 02:30pm
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All motors cab become generators. But you do need a controller to regulate the voltage and current to the battery and to prevent the 'generator' becoming a motor if the driven rotational speed drops too low.
PV solar is usually easier to set up but the 24/7 of mini hydro is attractive. But more work IMO. All the moving parts = more maintenance. Ditto on wind.
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