TOPIC:

Hello everyone,
OK, for those electrical geniuses out there...I was considering adding two small 35 watt spotlights (each, total 70 watt load) to my stock 1979 SR650. Probably mounted on crashbars or upper forks. I figured this will add about 6 amp load (70 watt / 12 volt = 5.83 amps)...likely to tie directly to my battery via a weather-proof switch on my handle bars.
My question, will my bike alternator/electrical circuit handle the extra load? I already have a halogen lamp but want to
to increase my visibility to other drivers, plus my own visibility at night to see better.
Is this a mod that others with stock 650 bikes have tried? What spotlight models have you used? Is there any negative results on your charging systems. I don't want to fry anything on my electrical system.
Thanks for any and all comments.

Post edited by: davenkids2001, at: 2007/03/28 21:02

Mine's a 900, uses a Kokusan AR3703 Generator (Dyno). According to the Kaw Repair Manual, it'll put out 9.5 amps at 4,000 rpm. When it was new.
Don't know how much your modified headlamp will draw, but the original bulb draws about 35W, and 50W on high beam.
Your tail light draws about 23W when you brake, and 8W when you don't.
All of the other little instrument lights draw only about 3.4W each.
Each turn signal bulb will draw 23W when it flashes, so that's 46W, intermittently.

If you figure 50W for your headlamp, and assume you're not riding the brake or turning, then your bulbs are pulling about 5.5 amps with your existing lights. You also need power for the coils, I don't know how much.
Adding another 6amp draw will probably tax your charging system, especially around town (where you need the lights) because of low rpms, braking, and turning.
If you add the lights, make sure you put a switch in the new circuit so you can turn the lights out and save your battery when your idling at a stop light. You can also get a little voltage gage so you can monitor your battery voltage and shut down your lights if you see a drop in voltage.

Thanks Ltdrider.
I have been reading up about this here in the archives to learn more about the electrical system. My manual isn't too informative.
I think I will postpone adding any electrical loads to our bike for now, until I learn more. I plan to borrrow an amphrobe from work and I will test existing current draws over the weekend.
KZRIDER is really a great forum. Thanks to all the writers here.
-Dave 'n Jan