Lewis Campbell's Lighting system
I've finally got around to testing some dynamos. I got Paul to make up a bracket to hold them on the tyre testing rig, so I've just measured the power taken to drive the wheel on a roller with the dynamo on the tyre and with it off. I've no intention of doing a "scientific" test, so NO claims are made about accuracy, the tests are simply for our own use, and I post them here in case others are interested. Tyre used was a 20" x 1 1/4" Hudyn HPV slick, at 80psi. Wheel loading was reduced to about 23kg instead of the usual 30kg for rolling resistance testing. "Road" speed was 28 kph (17.5 mph) This time, I'm just quoting the raw amps difference between the dynamo off the wheel on the wheel. Results are the av. of five runs, discarding the highest and lowest. Accuracy is probably + or - 0.02A. I used the Lumotec headlights with 3 watt QI bulbs. Dynamo Light Light Power Make & Type Volts Amps Amps B&M "6" 7.50V 0.495A 0.67A B&M "S6" 6.86V 0.456A 0.48A LightSPIN 6.40V 0.449A 0.32A Two Head lights LightSPIN 6.30V 0.900A 0.46A This does not measure the amount of light produced, but will give some idea for the relative amount of power required to drive the dynamos. I've used the S6 on a trike, and was not able to detect any increase in resistance from the dynamo in riding the trike. Obviously the higher the bulb voltage, the more light you get, at the expense of bulb life........ It does seem to me that the most efficient is the LightSPIN with two headlights, as Rob Hague has been using on his Greenspeed GTS. Note that the power voltage is not shown, so no efficiency %ages are indicated in these results.
Thursday, 29 January 2009