# Calculating wheel and motor size for run-of-river hydroelectric generator [closed]

I am a student designing a hydro electric generator used on rivers to collect kinetic energy from horizontal water flow, rather than potential energy from vertical water drops.

My idea is to turn a large wheel using the water flow, this is connected to a smaller wheel using a belt in order to increase RPM.

It is used solely to charge as many 17Ah 12V batteries as possible from the power generated.

A generator I have been looking at in particular is this: 1.3kw single-phase motor, 3400 RPM, 110VAC, 15.3A.

Here are my calculations:

• Water velocity = 2m/s, big wheel circumference = 75cm
• This gives 2.66 RPS which is 160RPM
• to reach the 3400 RPM of the motor the small wheel must be (3400/160) = 21.25 times smaller
• this means the circumference of the small wheel is (75cm /21.25) = 3.59cm
• this in turn means the diameter is (3.59/pi) = 1.12cm

It seems like this is a very small wheel to be turning such a large motor. Is this diameter too small to function correctly?

## closed as off-topic by LShaver, Jan Doggen, Fred, J. Chomel, A. A.Mar 23 '17 at 21:48

• This question does not appear to be about sustainable living within the scope defined in the help center.
If this question can be reworded to fit the rules in the help center, please edit the question.

• Welcome to Sustainability.SE! I edited your question and title a bit to make it more clear. However, I'm concerned this may not be a good fit on this site, and may do better over on Electronics.SE. But, let's leave it for a bit and see if anyone here has some insight. – LShaver Mar 4 '17 at 16:01
• My guess is that yes, that would be much too small. A belt would slip probably. This question may also be a good fit for engineering.stackexchange.com as they could likely suggest a solution... – Highly Irregular Mar 5 '17 at 1:07
• How is this question different from one recently posted on SE Engineering? – Fred Mar 5 '17 at 2:07
• I'm voting to close this question as off-topic because it's a better fit on engineering.SE, where it has already been discussed: engineering.stackexchange.com/q/14045 – LShaver Mar 6 '17 at 18:44