# Small wind turbine to charge 2 - 12 V batteries for school project

Registered Users Posts: 3
Hello Everyone,

My son would like to build a system that uses wind to charge his E100 scooter. His idea is to create small wind turbines and connect to the existing motor which will in turn charge his batteries. I really dont know enough about this to help him but want to do as much as I can. Can anyone guide us?

• Banned Posts: 17,615 ✭✭✭
Re: Small wind turbine to charge 2 - 12 V batteries for school project

Welcome to the forum.

"His idea is to create small wind turbines and connect to the existing motor which will in turn charge his batteries."

So the motor turns the turbines which charge the batteries which run the motor?
This is called "perpetual motion" and has a 100% impossibility factor.

Nor can you mount wind turbines on any sort of vehicle and have them recharge the batteries while the vehicle is in motion as the drag of the turbine blades will exceed the equivalent power that is generated. The except to this would be to go downhill when the motor isn't providing the motif force (and thus using battery power).

You can set up wind turbines to catch the wind while the bike is stationary to recharge the batteries. You will find most commercial small turbines are fairly disappointing for this; a lot of money and a little return.

So, which way do you want to go with this?
• Solar Expert Posts: 891 ✭✭✭✭
Re: Small wind turbine to charge 2 - 12 V batteries for school project
My son would like to build a system that uses wind to charge his E100 scooter. His idea is to create small wind turbines and connect to the existing motor which will in turn charge his batteries.

So you are saying that he has a permanent magnet motor and wants to bolt a "windmill" on the shaft and use it as a wind turbine? That can work out if the voltages match. The big issue is that a given windmill/turbine will turn at approximate speed in a given wind, and that will provide some voltage at the output of the motor. If that's the right voltage, great. If not, then you have to change the turbine pitch, or rewind the motor, or boost/buck the voltage.

Don't expect to get a lot of power but it might be fun to try.
• Registered Users Posts: 3
Re: Small wind turbine to charge 2 - 12 V batteries for school project

Well, we will have to scrap that one for sure... he was just trying to figure out a project for his senior project in High School Engineering to make use of his scooter...

"His idea is to create small wind turbines and connect to the existing motor which will in turn charge his batteries."
So the motor turns the turbines which charge the batteries which run the motor?
This is called "perpetual motion" and has a 100% impossibility factor.

Nor can you mount wind turbines on any sort of vehicle and have them recharge the batteries while the vehicle is in motion as the drag of the turbine blades will exceed the equivalent power that is generated. The except to this would be to go downhill when the motor isn't providing the motif force (and thus using battery power).

You can set up wind turbines to catch the wind while the bike is stationary to recharge the batteries. You will find most commercial small turbines are fairly disappointing for this; a lot of money and a little return.

So, which way do you want to go with this?
• Banned Posts: 17,615 ✭✭✭
Re: Small wind turbine to charge 2 - 12 V batteries for school project

Being able to quickly unbolt the PM motor from the bike and slip it into a turbine mount to recharge when the bike is at home would be interesting. Pretty impractical, but interesting.
• Solar Expert Posts: 762 ✭✭✭
Re: Small wind turbine to charge 2 - 12 V batteries for school project
Well, we will have to scrap that one for sure... he was just trying to figure out a project for his senior project in High School Engineering to make use of his scooter...

It was a very intelligent thing to ask! The problem is that even if you discount aerodynamic losses, you couldn't build one big enough and ride long enough to provide a decent charge to the E100 scooter. Heck even newcomers to stationary turbines in the back yard find this out the hard way - not enough power and not long enough to be practical.

The danger here is that yes, you *could* prove that a mobile turbine will provide some amount of energy to the system, but in the real world, it won't fly on a practical basis.

Is he willing to change his project to a large stationary turbine and/or solar?
• Registered Users Posts: 3
Re: Small wind turbine to charge 2 - 12 V batteries for school project

I think he would certainly entertain the idea... whatever we decide it has to be affordable as we are limited in our resources and of course practical as he needs to transport to school. What would be your suggestion?

PNjunction wrote: »
It was a very intelligent thing to ask! The problem is that even if you discount aerodynamic losses, you couldn't build one big enough and ride long enough to provide a decent charge to the E100 scooter. Heck even newcomers to stationary turbines in the back yard find this out the hard way - not enough power and not long enough to be practical.

The danger here is that yes, you *could* prove that a mobile turbine will provide some amount of energy to the system, but in the real world, it won't fly on a practical basis.

Is he willing to change his project to a large stationary turbine and/or solar?
Re: Small wind turbine to charge 2 - 12 V batteries for school project

Typically the most cost effective:

Solar panel and a 12 VDC battery bank (deep cycle type battery). A Charge Controller of some type to charge the deep cycle battery. Get a 12 VDC charger for the scooter or use an AC inverter+AC Scooter charger. Charge the fixed battery in the sun--Charge the scooter (day or night) when convenient.

Or a solar panel charging the scooter directly. You need a charger compatible with Solar panel to Scooter Battery (if Lead Acid and standard voltage), not too difficult. If LiIon scooter battery or other "high tech battery", may not be easy (or safe) to charge with the wrong charge controller. Obviously, can only charge the battery during ~9am-3pm, or you have a second battery pack to charge during the day.

Need to have a good idea of the battery capacity, voltage, battery chemistry and how much the scooter is driven (i.e., recharge the battery 50% per day).

If you have an AC battery charger, you can begin with a Kill-a-Watt type meter to estimate how many kWatt*Hours per day you need to recharge the scooter.

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset