... now i understand the need for a metal heatsink.
YES, good point ... so better not to exaggerate with resin impregnation to make the thing IP69!!!
Here below:
Picture 1 shows Voltage and Frequency at no-load conditions at 20 km/h on a 28" wheel.
Picture 2 shows Voltage and Frequency on a 12 Ohm resistor at 20 km/h on a 28" wheel.
Below data are referred to Shimano DH-3D32-QR hub dynamo.
![](https://4.bp.blogspot.com/-3C1RKQKlmsU/V7wDUFNwA1I/AAAAAAAAVyQ/TLON5Pejq38exMFAdT-9zYgmeJ-CGmDcwCLcB/s320/Frequency%2Bat%2B20kmh.jpg)
![](https://4.bp.blogspot.com/-R9GVuF-fnxw/V7wfViknP5I/AAAAAAAAVyg/A9RHDy2BN-guwPHJeNPsvQ3cmNeWBLq8gCLcB/s320/Frequency%2Band%2BVoltage%2Bat%2B20kmh_12%2BOhm.JPG)