Triumphrat

badrufus · 12-04-2005

I have a pair of Moto-Lights that draw 70 watts total, so I too have been concerned about the draw on the system. From what I understand, the 865 cc Bonnie puts out 27 amps or 324 watts, just as gypsy56 says. The tricky part is to figure out how much of that is unused, and thus available for lights, electric clothing, etc. The really tricky part is that the power output varies with the rpm. I hooked up a digital multimeter to my battery and discovered that when just idling, the 70 watt lights would draw down the battery; while at 2000 rpm, the reading was the same with the lights on as with the lights off (14.7 V), so at 2000 rpm plus, it seems that the charging system can keep up with the draw being placed on it. My mechanic had expressed concerns about the lights, and simply suggested turning them off when idling for any length of time. Now I see why. Motorcycle batteries are not deep draw batteries--they don't like to be deeply discharged and then recharged, but rather, like to maintain a fairly steady charge. Likewise, the electrical charging system on the Bonnie isn't really designed to run a bunch of extra wattage without eventually frying some parts. My solution has been to run the lights when I'm not in stop and go traffic. If I hook up my Gerbring jacket at 77 watts, I will make sure to turn it off when idling. I'm assuming that running both the jacket and lights at the same time would be pushing my luck.