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Water Wheel Electricity
make electricity with your water wheel

To see pictures of my water wheels click HERE.

 Making electricity @ your home or business isn't rocket science. Give me 10 minutes and you'll understand the basics of what is needed for making your own electricity from water and wind. Thousands of pages have been written on the subject , many of which require a Masters degree to understand so I'm just going to give you the basics here but enough information to take the wind or hydro power you now have and make electricity from it. This page isn't designed for solar power although the meters and charge controlers used will work well with solar power systems. It will cover how to roughly calculate your site's potential power, what generator to use, why you want a charge controller, power meters, and how to store/use this electricity. At the bottom of this page you'll find a diagram showing a system like the ones covered here made from only five wires for a simple 12 volt system. For example equipment I'm using equipment I use (and sell) because I've tried a lot of stuff over the years and these are the easiest to use pieces I've found and they work well together. You can web surf and find different equipment if you want, just make sure it all works well together     You choose how to spin the alternator. I like water wheels and hydro turbines because if you've got the water they make electricity 24 hours a day but wind turbines and even human powered bikes can make electricity with this simple system.

Ok folks, Search Engines are seriously lowering my web listing due to a lack of links to this website. Please link to this website so it ranks higher on search engines so I can afford to provide this information. The lack of links is affecting my financial ability to care for my family. I spend several hours each week helping people over the phone and email learn how to make electricity and rarely making any money doing it. I need you to link to my website if I am to continue providing this information. Spencer Boyd  

An alternator is what you'll use to make the electricity. Alternators like your car has can turn on (making electricity) or off (not making electricity) but aren't very efficient. Permanent magnet alternators ( PMA ) are more efficient at turning the potential power you have into electricity but make electricity whenever they spin.... they always make electricity when spinning- a point to remember later... Low RPM permanent magnet alternators are the best because they make more electricity at lower speeds but are more limited in their electrical output at the higher end. PM (permanent magnet) motors with a diode can also make electricity but unlike a low RPM permanent magnet alternator (PMA) they need to spin really fast (up to 9000 rpm) to make the power. All alternators, even your car's, can make high voltage if not hooked to a load like a battery; a subject to be discussed later on this page.

The second thing about alternators and the fact you need to understand is that even a 12v alternator will make over 100 volts if it isn't connected to a "load", on most small systems, a battery is the load. A 12v alternator can charge a 24v or 48v battery but the alternator needs to spin faster to reach these higher voltages.

Imagine that your 12v alternator is a pump and the faster it spins the more water (or watts) it pumps and it pumps at higher pressure (or higher voltage). If it pumped it straight up a pipe it would pump it up well over 100' (or 100 volts) before it reached the end of it's abilities but at 100 feet (or volts) something would probably break or burn out because the system wasn't designed for that much pressure or voltage. What if at 13.6 feet up the pipe we put in a huge water tank ( battery). It would hold the water level (voltage level) at about 13.6 feet or 13.6 volts for a long time until it filled up. The water tank (or battery) is your "load" holding the voltage around the desired 13.6v. But once the water tank is full the water would keep going up making higher pressures (or voltage) unless we put a switch box with a valve to send any water (or electricity) over 14 feet (or 14volts) up the pipe out a hole in the pipe so that the water (or voltage) can't get over 14 feet (14 v) protecting the system from too much voltage. The switch box would be called a load controller and it reads your battery voltage and when it sees the voltage getting too high because the battery is full it sends the extra electricity to a load dump which like the hole in the pipe 14 feet up dumps extra water (or electricity) away. Most systems use electrical heating elements for the dump load to dissipate the extra electricity as heat. Sometimes you may use electricity from the battery lowering the voltage and the controller switches back to sending the electricity from your alternator to the battery refilling it for you.

In this very simple example voltage is like water pressure. The higher up the pipe the water goes the more pressure created. Watts are like water volume. A watt is a watt just like a gallon is a gallon. It may be under more pressure (higher voltage) but it's still 1 watt. Amps are a measure of the total flow (watts / volts = amps) through the wire or pipe. Higher pressure would move the water faster increasing the total amount of gallons (or watts) moving through the pipe and higher voltages (higher pressures) will move more electricity through a wire. Too much power will burn a wire out.

If you use a 12v battery the system will settle at about 13.6 volts. With a 24v battery the system will settle at about 26.8 volts until the batteries get full and the extra energy needs to be dumped. Most of the charge controllers I sell can be set for either voltage (even 48v) protecting your battery.

You want to make sure that you get a good PMA (or altinator) because it is the heart of your system. There are a lot of junk PMA's out there and even one major name brand that is bad about burning out so choose carefully, The PMA's I sell and use on my turbines are the best PMA's I've ever used. Also these examples are very basic and ignore Ohms (resistance) ect so... if you choose to get your different parts for your system from different places be sure that they will work well together.

In review.... The faster you spin the alternator the more electricity it will make but low RPM alternators (also called PMAs) start making electricity at much lower speeds than a car type alternator or PM motor and will make more power since their more efficient. Your load (usually a battery) will keep the voltage at the same level as the battery once the alternator is spinning fast enough to reach the same voltage the battery is. When the alternator is spinning faster the battery will keep the voltage at the battery's voltage. A charge controller acts like a valve or switch that sees when the battery is full and sends the extra electricity to a dump load like a heating element and back to your battery when it needs more electricity.

Let's discuss load dumps which are simply small electric heaters. You need some way to dissipate the extra electricity yourr charge controller sends away when the battery is full. If the dump is too small to burn off all the power voltage will rise maybe damaging your system. If the load is too large your alternator will act like a brake on your turbine or water wheel. Most load dumps can be hooked together allowing you to use several together to burn the power level you want. So,,, You want a load dump that is between 120% and 150% of the maximum power level your alternator is likely to produce. Simply figure a realistic maximum power output for your alternator when used @ your site.    Now to figure how large of a load dump you need.

Example: If you figure your system will make about 200 watts you will need a load dump that can burn at least 240 watts 200 watts x 1.2 (120%) = 240 but not more than 300 watts 200 watts x 1.5 (150 %) = 300 watts In this case I'd either get a 300 watt load dump designed for your system's voltage (12v or 24v or even 48v) or hook three 100 watt elements together… either way you've got the correct size load dump for your system. If in doubt use a slightly larger load dump.

Since ohms add another level of complexity to this subject I'm not going into using odd-ball heating elements. Yes you can use almost any electric heating element, even a hot water element could do but due to Ohms (Ohms is a measure of electrical resistance) we're not going to discuss the math on how to choose the right size. Instead let's keep it simple.

Ok, Spinning the alternator makes the electricity, the charge controller tells the electricity where to go and the load dump burns off the extra electricity to protect your system. Most people with small systems feed the electricity to a battery or batteries to store it up or a small grid tie inverter. To keep things simple I'm going to use 12v for this discussion although higher voltages like 24v and 48v systems can be a tad more efficient.

We all want a bunch of big giant batteries to store up a lot of power but that usually isn't the best choice for most small systems. Batteries have a little resistance to being charged and tend to last longer and charge more completely when charged at the correct rate. Batteries will charge at a much lower rate but will not last as long (long story why). A basic rule of thumb is to charge a 12v battery with at least 1 amp (12 watts) for every 20 hours of reserve capacity. Ok,, I know I lost most of you with that one but it's easy. Look at the sticker on the battery. If it says 300 amp hour reserve or capacity 300 / 20 = 15 so this battery likes to be charged with at least 15 amps. So... 15 (amps) x 12 volts = 180watts so this is a good size battery for a system making 180 watts. You will still get many years of service from this 300 amp battery if you only charge it with 5 amps (62 watts) but for the most life from your battery charge it with the correct amount of power. Most people with small systems ignore this rule and are happy with their results as long as they don't try to hook up a bunch of huge batteries to a tiny system. Also different types of batteries like to charge at slightly different voltages (example: most 12v gel type batteries like to charge at 14.3 volts) and a decent charge controller will let you adjust the charge voltage slightly to match your battery's appitite.

As you probably know voltage drops over long wire runs and this is especially true with low voltage systems. If there is more than about 70 feet between your alternator and your batteries you will probably want to run 3 wires (3 phase) instead of 2 wires ( DC direct ) which is easy to do with a rectifier close to your batteries. A rectifier takes the 3 wires coming off the alternator’s plug and makes it into 2 wires to hook into your charge controller or can be hooked directly into your battery. By using a 3 phase wire run you can use smaller less expensive wire to minimize voltage drop on longer wire runs.

Battery choices: A 12v car battery will work but tends to not last very long when cycled down a lot. Better are the deep cycle batteries boats use and can be found at most auto part stores. They last longer and can be drawn down further without risking damage to the battery. Golf cart batteries are an even better choice and the best but most expensive choice are the specialized batteries used by professional solar and turbine installers like L-88s.

Once the electricity is in the batteries you can either use it as 12v or 24v DC directly from the batteries. Or you can get an inexpensive modified-sine wave inverter at most truck stops, online or even Wal-Mart and plug most 120v AC things into it but you don't want to plug very sensitive items such as a plasma TV or a desktop computer. A pure-sine wave inverter cost more but makes "cleaner" electricity good for all electrical stuff in your home.

If you are looking to feed the electricity directly to the local grid there are "grid tie" inverters available like those made by Outback and Sunny Boy which require contacting you local utility and using an electrician for the instalation. There are smaller grid-tie inverters on E-Bay that don't require an electrician to hook up but local utilities don't like these units so use at your own risk.

You can find really chea Oh yea, I almost forgot power meters. Not required but they sure are nice, especially an amp meter. Automotive meters work well but there is nothing like a big LED display to let you see how your system is doing. Good meters will also help you see any problems like leaves in your water turbine. Remember: Amps X Volts = Watts and watts are what it’s all about. Watts are the actual measure of energy. So if your meter shows 14 volts and 22 amps (14 X 22) = 308 watts of pure electricity flowing where you can use it. Nice.

You can research the heck out of the subject and maybe end up with a more efficient system but a small system (less than 1500 watts) designed like this one is pretty darn efficient and will last many years safely making electricity.

You've talked the talk, now its time to build the darn thing and make your own electricity.

Note: I spend at least 5 hours on the phone and email each week with people who want to pick my brain for hard won knowledge about how to do this or that with no intention of actually purchasing from me. I need to feed my family too so please do not contact me unless you are interested in purchasing something from me. I realize this is a little rude but I've got to feed my family too.






Calculate the potential power you have

Ok, So now that you know how much water and how much head you have we can do some simple calculations to figure out how much power we can make.


Gallons per Minute
  Head Height, Waterwheel Diameter (feet)
  Efficiency (use .55)

First a few facts to help you picture what these results mean.

1 horsepower equals 746 watts of energy

A 60 watt lightbulb needs 60 watts of energy to light up

A LED bulb only needs about 2 watts to run

These numbers will help you picture what your calculations mean. A well designed overshot water wheel is about 80% efficient @ converting the water's energy into torque @ the wheel's axle. Since the wheel spins slow (7-10 rpm) and the alternator needs to spin fast you will need some gearing to speed things up. In addition to this your alternator and charge controler aren't perfect either so between the gearing and the alternator you will loose an additional 25%-30% of your wheel's energy so... total system efficiency will be around 55%. When using the following formula if you use .80 for the efficiency you will be measuring the energy @ the wheel's axle. If you use 55% for the efficiency you will get a realistic figure for how much electricity you will actually be producing with a water wheel.

Or if you want to do these calculations manually the horsepower of your water wheel can be calculated by


# of gallons per minute x .000253 x height in feet x efficiency = horsepower

So if you have 700 gallons per minute of flow and are using a 8' diamater water wheel and was looking to see how much electricity (55% total system efficiency) you could make it would look like this.

700 x .000253 x 8 x .55 = .779 horsepower

So if 1 hp is 746 watts you could say .779 x 746 = 581 watts of electricity would be make by this water wheel which is enough to run nine 60 watt light bulbs for as long as the wheel is turning with a little power left over.

If you were more interested in the power @ the wheel's shaft and the wheel is 80% efficient it would look like this.

700 x .000253 x 8 x .80 = 1.13 hp

So if 1 hp is 746 watts... 1.13 x 746 = 843 watts potential @ the wheel's axle.

A thought to help you understand

The constant (.000253) is the water weight in pounds divided by the foot pounds per minute. The height is the water wheel diameter so if you have 9' of head but are only running a 6 foot diameter wheel the height for this calculation is 6 feet. Most people use 12v batteries to store their electricity and an inverter (available @ Radio Shack, local truck stops, or online) to make the power into 120v AC. Since the batteries store up excess energy a water wheel making only 100 watts of electricity can run a 1200 watt microwave oven by using the energy stored over time in the batteries.