Hi I am working on a wind turbine competition as far as the competition is going, designing my turbine and everything else, it's actually going quite well so far. But the one aspect which I have been scratching my head for a while has been the generators I have to use to make electrical energy. As part of the competition I was given 3 unlabeled D/C generators of which I must choose 1 ( I believe they're D/C generators although I am not sure) I figure I could determine its specifications if I run each generator at such and such an RPM for each generator then with a multi-meter measure the volts and amps. My questions would then be:  Is this a good way to determine each generators specifications?  If I keep increasing the RPM to acquire accurate measurements is there a risk I can accidentally destroy my generators?  Is there a way I can figure out if it is A/C, D/C (good band by the way lol)  Is there a maximum electrical output that each generator is constrained by in which if it try to pass a certain RPM no further gains will be made? Lastly I was given vague instructions, but the instructions said there are 3 generators however I was also given a 4th of some kind motor/generator, I am uncertain what it is, it has alligator clipping but no axle extrusion from which I could spin it to try and see its output. I would genuinely appreciate any help, there so small I was afraid to test any of them for fear I might break them and if I break them the organization said they will not give me replacement generators so I decided to come here for help :D. Thank you again for taking the time to read this I have pictures in the attachments below in case you were wondering what they looked like.