When evaluating an electric dynamo, you must prioritize Power Output (Watts/Kilowatts) and Voltage Stability. Ensure the winding material is 100% high-conductivity copper rather than copper-clad aluminum (CCA) to prevent overheating and ensure longevity. Additionally, verify the RPM (Rotations Per Minute) requirements to match your prime mover (e.g., wind turbine, water wheel, or engine) and check for IP54 or IP55 ingress protection ratings if the unit will be used in outdoor or dusty environments.