This looks really ingenious! --Tomhannen 16:50, 3 January 2008 (EST)
Great stuff Arjun. How are you ‘starting’ the alternator? Are you using a car battery or one of the laptops to put a current through the field coil?
Also how is a voltage being fed back to the alternator to regulate the output?
- Thanks Josh. The alternator is starting from the same car battery that is getting charged from the Alternator. Earlier we wanted to charge the laptops directly when we were using the dynamo in our aim to avoid using a battery. Now since we have changed over to an alternator, we are using the same car battery to start the alternator as the same one which we charge. We subsequently charge the XOs from the car battery. This also saves us having to put expensive copper wires from the generation area to an area where the XOs are getting charged. Also, the car alternators have a built in output regulation and rectification mechanism. --Arjs 15:22, 4 January 2008 (EST)
In many systems where power is being produced and recharging batteries a diversion load is required to prevent overcharging of batteries. A diversion load is basically a big heating coil which dissipates excess energy. Is something like this required for alternators? JoshSeal 14:05, 4 January 2008 (EST)
- As I mentioned in the above section, the alternators are the same ones used in cars hence have a regulation and rectification mechanism. They also cutoff the output when the battery is fully charged. --Arjs 15:25, 4 January 2008 (EST)
Do you need some way to adjust belt tension? This would allow for use of different belts, depending upon their availability. Also, I assume that if you are considering v-belts, then you will need to use a pully that is sized to fit the belt. Would this make adaptation more difficult?
- We need to determine the belt best suited for our tension value (3500N). In general would you suggest using a flat belt for this purpose or a V belt ? Our current setup uses V belts (and pulleys corresponding to V belts) but we are considering switching to flat belt in our modified design since people have told us that flat belts are better suited for higher tensions. Thoughts ? --Arjs 22:34, 6 January 2008 (EST)
- For serious load, belts seem to be semi-flat. They have multiple grooves and/or teeth. AlbertCahalan 02:37, 7 January 2008 (EST)
The following link has a brief discussion of V-belt verses flat belt. It then digresses into an advertisement, but I thought it was useful. http://www.designnews.com/article/CA220670.html
For low-RPM, high-tension applications, (bicycle) chains may be a better option. Also readily available ready-connected to a bicycle wheel as in the diagrams. I am open to correction on this ...--Paul B. 08:05, 3 April 2009 (UTC)
There is a South African variation on this theme with supoort from the Lemelson Foundation. A play-powered roundabout (merry-go-round) that provides water pumping (and in planned versions, electricity generation) in rural schoolyards.
Cjl 01:13, 23 February 2008 (EST)
Inputs from Matt York
Although auto alternators amy be somewhat abundant, they are not well suited for human or animal "spinning". Automotive alternators are design for high RPMs; at 2000-2500 RPM, alternators are putting out about 60-70% of their capacity. This forced the Cow Power test to get sidetracked into developing excessive pulleys and belts. Even if they had succeeded, the maintenance of the belts and pulleys (over the useful life of the device) would be extremely burdensome.
If labor is cheap and the supplies are available, the rewinding of an automotive alternator is a better use of resources. http://www.mtmscientific.com/rewind.html
Also.... Stepper motors can be used as genertors requiring lower RPMs. Stepper Motors have an advantage that they have multiple poles, allowing generating useable electricity with low rotation speed, thus eliminating the need for gears or belts when cranked by people or cows. While stepper motors, when used as hand-cranked generators, require multi-phase rectifiers, these rectifiers are far easier to make than gears. http://www.c-realevents.demon.co.uk/steppers/stepmotor.htm
"Smart drive washing machine motors" can be converted into low RPM generators. http://www.ecoinnovation.co.nz/c-45-manuals.aspx