how to build a battery generator for a science fair project?

Answer 1

Depending on the size of the Battery. Find an electric motor that use the same voltage and connect an outside source to turn it. Motors work on the same principle as a generator (To be simple about this). If, you apply voltage to the motor it will turn, if, you turn the motor in some way; it produce voltage. You can test what I say with window fans. Take two and face them toward each other. Turn on on high and it will make the other fan turn. Take an AC volt meter and measure the voltage at the plug of the fan that being turned. The faster you can make the fan turn the better your output voltage. This work the same with a little electric motor for your generator. If, it run on 12 volts DC then it will output the same, if, it turned fast enough and actually charge a battery. Hope this enough to help.

Answer 2

>How many watts can Micro Hydro generator make using a garden hose? A few watts. >will the garden hose generate enough RPMs? The important question is, how much kinetic energy is there in the water coming out of the hose? The amount of energy you can get from the generator is less than the amount of energy you start with in the water stream. That's a lot less than 350 watts! If you read the AIDG write up on what results they got in the field, with a 2" pipe and 30 meters of hydraulic head, they got 60 watts of power. I'm guessing that an ordinary water hose might have an order of magnitude less energy available, so lets guess 6 watts. ---------------------------------------... >I think there is some confusion with my question. I was referring to a regular garden hose connected to a house tap facet at the school. No streams or gravity feed. I'm not confused about what you meant. Why do you think that the water flowing out of a garden hose is any different in principle than the pipes in the the examples I linked to? The point is that you would need (very roughly) 100 times the energy available from your water hose to power the generator you described. You need to look at something that will produce something in the range of 1 to 10 watts, not 350 to 1971 watts. -------------------------------------- Added comment: Why not start by finding out how much energy is available from the hose? Get a bucket & watch, then measure the flow rate (liters per minute). Then point the hose upwards and estimate how high the water stream reaches. Try the same measurements with a nozzle to decrease flow & increase the velocity of the water. Find a physics book or ask in a science/engineering forum if you need help in calculating the energy from the measurements.