Hi.
These thoughts based on a few decades experience on the subject at hand,
BUT are from a very different power system region (~1 230V / ~3 400V) and also from a different consumer environment, but I'd assume that those differences don't exactly work in Your favour in this case.
My question: If I were to reverse the fan blade, or fashion a larger fan blade, mounted to make the motor spin in reverse (or just spin), could I convert any of these motors into wind generators, using the power leads as the current outputs?
Yes, almost every electrical motor design can be run as a generator and vice versa.
Some without any modifications, some require extensive modifications.
Some with high efficiency, some with practically none.
When You run an AC electrical motor overspeed, it creates voltage if the field is excited.
The direction it runs, usually doesn't make a difference.
Is there current generated by simply spinning an electric motor? Or am I just way off in my thinking? If there is some current generated, would it be enough to power, maybe a light for camping, or something else?
Only a handful of electrical motors are able to convert power without
controllable excition, any voltage You can measure without the load is being converted with the aid of remnant magnetism or stray fields. Or both.
As soon as any significant load is applied, the voltage(s) drops to 0.
I'm not kidding I have five big motors right now....four from compressors, one a commercial 220 garbage disposal, that all spin freely, and worked when removed.
Define big, 10KW range?
It's all about commutators v slip-rings.
Only partly correct IMO, it's all about applied science and engineering.
What is true though, the commutator motors are no-brainers, and except for the permanent magnet motors/generators, those are probably the easiest to use as a motor and a generator.
To the untrained eye, motors and generators look almost identical : magnets, coils, wires and lots of spinning.
But there are subtle design differences that allow one device to turn electricity into kinetic energy (motor) and the other to turn kinetic energy into electricity (generator).
Fortunately those subtle differences are often easy to modify to suit either or both tasks
.
Plans for such conversions are about as old as the motors/generator themselves.
I'm working by memory here, but I'm pretty sure the disposal had 5 wires, could be six. The fridge motors were definitely black/white/green.
The number of leads alone unfortunately tells You nothing about the motor/generator.
Only the wiring diagram does.
And the label(s).
Of course, one can assume that one or two lead motor/generator is either one phase or DC unit, but that's about it.
Plenty of AC units have starting capacitors, quite a few have running capacitors, some have both.
Some of those caps are inside the connection case, some are mounted externally.
Some have extra shielding, some have none.
Some have an independent neutral wire, some have none.
2 or more speed motors can have any number of ways how the speed is changed, and the number of leads is different if the switching is internal or external.
The best way to avoid the hassle is to have a label and/or a wiring diagram (often found cast on the inside of the connection case lid), but every time an unknown motor is removed, the leads must be marked.
Otherwise it's pretty much useless, or at least a major PITA to measure and guess how exactly 10 leads for example are connected.
As for Your second question about old random electrical motor market, I'd say it's IME about as big as the one for used guitar strings.
There's a demand and a market for both, even with todays prices, but very few bother because of the hassle and very small profit margin involved.
At least that's the situation here.
In Your case the fact that it's industrial units these motors came from can work in your advantage if you can sell them as spares. You need to know
exactly into what models the motors are suitable for though, and probably also into which models they can be converted to work in.
You also have to find someone who's comfortable in buying an unit of unknown hours and unknown condition.
Ain't gonna be easy if You ask me
.
As for the "independent from the line grid power DIY style" question, what's Your power demand?
IMO/IME the most feasible choices are:
If less than 100W, stepper motors (permanent magnet motor) or an alternator/generator.
If from 100W to 4KW, an automotive alternator.
From 4KW to about 20KW, I for one haven't found a DIY solution that was cheaper than the Chinese generators or several alternators.
From 20KW up a 3 phase motor with a modified rotor.
A stepper motor can act as an AC generator without any modifications, and plans for the regulating units for DC conversion are all over the 'net.
Very handy for camping and such with LiIon batteries and LED's as the light source.
An alternator is nice device for a DIYer because one can get either ~3 AC or DC (or both) from the same unit, and the voltage is highly controllable.
The on the shelf units range from about 100W to about 4KW, parts are cheap, as are the units themselves.
In theory, the direction of rotation matters because the brushes are off-set into the designed running direction, but IME (90KKm in a motorcycle), the extra wear on the brushes was neglible.
Both the stepper motors and the alternators can drive an inverter if needed,
if the units are appropriately sized and designed.
The following assumes that any governing necessary is external:
Modding a 3 phase motor into a 1 or 2*1 phase generator is very easy, but also very inefficient.
All that's needed is a few capacitors.
Modding a 3 phase motor into a 3 phase generator with any kind of decent efficiency is pretty hard, or at least involves quite a bit of engineering knowledge, but if the original rotor is redesigned, it becomes relatively easy.
Regards
Sam
