In looking online, it looks like when developing a wind/water mill-like generator, a high voltage motor is best to generate battery charging ability at low RPMs. One of the problems with any hobby-type toy motors is that they need to be spun really fast to get some good voltage out of them.
But if i add gearing to the hobby motors then they become too difficult for gentle winds/water to move the fins of the generator.
Is there any middle ground of hobby level motors that anyone has come across, that can generate significant voltages when the output shaft is at low rpms? Like less than 50rpm with no gearing?
If there aren't such motors easily available, is there another way of harnessing low winds/water to charge batteries.
In my previous post i got some good ideas about harvesting voltage from a lone solar cell over time, and then running my high-power device for a short time. I'd like to use that idea for that application, and find a suitable motor for this one, where i don't have to harvest tiny amounts of energy over a long period of time. Any suggestions are most welcome!
I did some reasearch but there are better ways to approach this. Have you heard of an electro-static genrator or a tesla free energy generator. I think you might find that easier to build and more efficient. In case you are wondering what a tesla generator is just follow the schematic below and for the torus just wrap it around the a can where water is flowing through it. Good luck.
Thanks for those two links. I think the schematic you were posting didn’t go through. or do you mean the schematic from the youtube link? But i didn’t see any torus-like thing going on in the video.
I am sorry just follow the first link. I also like conspiricies especially those on Nikola Tesla because he is awsome. Also this is a good example of a electostatic turbine. Enjoy.
ok I think i figured out how to measure it correctly. I made a circuit with an LED and resistor, and used the motor in place of a battery. Then when i interrupt the circuit with the multimeter test leads to measure mA, it doesn’t stall the motor.
When i spin the motor, the led lights up and i get really low (and realistic) readings of the small gear motor, which generates about 4mA max. i’m going to look around for some bigger motors!
whoa k i got it all wrong then, thanks for the clarification and help so far everyone!
So if a motor is rated for 9A at 24V and 240RPM, then i can take a rough estimate of it generating
4.5A at 120RPM
2.25A at 60RPM
1.125A at 30RPM
0.56A at 15RPM
0.28A at 7.5RPM
The bad thing is that the motor is part of an assembly and it has a metal attachment on the shaft that cant be easily removed. I’d have to make a jig and hammer it out! but i will most likely go back to the store early tomorrow morning and get a refund, and look for a motor i can use right away.
The surplus store had some motors that said 52V but they were too large and heavy. I’m planning on affixing a motor to a shopping cart to generate electricty.
Another option is a stepper motor i guess, lots of used ones around the surplus store. I’ve been doing more research and it looks like i can get decent voltages from a “boxy” space saving high voltage stepper. and no gear box would be required. But i’ve noticed that stepper motors are really difficult to spin when they are larger, so i’m afraid my shopping cart won’t roll along smoothly if i use one.
I’ll continue to search for motors, and i will also need to build a supercapacitor charging circuit to power the radio in the shopping cart, lol!
I looked up steppers before and it looks like i can get DC out of them by using 8 diodes in 2 rectifier arrays. For the supercapacitors, if i use a 12V capacitor, but the motor is 50V, there is a chance that at low RPMs that the motor output voltage will be more than the capacitors, i think i read somewhere that i would need to have some type of circuit in place (buck) to keep things under control.
I do often look up electronics 101 LOL! it seems that everytime i’m on th everge of success with some project, there is some new area of study that brings me back to feeling like an absolute beginner.
My first plan was to build a water turbine generator for a school project, went out to buy parts and building materials, the very next day i was forced to switch my project to a wheel generator (i’m choosing a shopping cart). returned all the supplies so now i’m sitting with a caster wheel and a gear motor that i can’t take the shaft contraption off, and even if i did, the motor might be a bit too stiff for the shopping cart to roll easily.
Now i’ll have to go back and return the gear motor, and look for some other motor or gear box/belt combo that can generate me some power from the shopping cart movement, which is probably less than 10RPM, and power a digital photo frame (that runs on a 5V 1A wall adapter).
There were some large motors at the surplus store…the problem with the surplus store is they have no shaft couplers, so i can’t ealisy “frankenstein” a motor and gearbox combo out of parts i find. Oh well, all a part of the learning process:)
Half rpm = half power output. How the power output is divided in voltage and current depends on the RPM and the friction of the motor. Then high voltage motors are less efficient at low voltages, because they have more gearing; at 7RPM they might not generate current at all, because all the power is just spent by friction as heat.
