Hi,
My first post here.
I have a treadmill motor that I intend to use for a wind or hydro project. It's an Icon B4CPM-0891 PM 130 VDC 2 HP motor that's rated at 5950 RPMs.
Using the calculator from the FAQ, here are the characteristics this motor should have -- 5950/130 = 45.8 RPM/V. So, it should offer 14 V for charging at 640 RPMs.
However, when I spin it in my drill press to 640 RPMs, I see 9.29 V. It doesn't approach 14 V until approximately 950 RPMs.
I had a look at the motor's brushes and armature, which appear fine. I also calibrated the drill press LCD, so I know that the display is accurate. I have another 96V Icon treadmill motor that doesn't have RPM information on its sticker, but also requires approximately 950 RPMs to reach 12 V charging voltage.
I am fairly new to DIY generation, so please forgive me if I've missed something obvious here... but this doesn't make sense to me.