[Captnorm30]

Hey everyone, so I'm interested in installing an small 18w LED light on my bike, to supplement the factory headlight for night riding and off road riding. Planning to wire a switch so I can control when it's on and off. Legal issues asside about "fog lights", I am mainly concerned about my stator. The light claims to be "low draw LED", and says it wont effect battery charge, etc...

Assuming my stator is oem, and I have a joe blow nothing fancy battery (but in good worKing order), you guys think it could handle an 18w draw without compromising anything on the bike? I'm riding a cb250, with no aftermarket anything (electronically speaking), no other draws on its power plant. Any thoughts?

 

[WintrSol]

Is that the advertising '18W equivalent' LED, or an actual 18W? Most quality LEDs have the light output of a filament bulb that has ~5 times the power rating of the LED, so a LED that draws about 3.5W will be advertised as 18W light output. My LED that draws ~3A at 12V (36W) is brighter than any 35W stock bulb, and seems to exceed the output of a good H4 100W bulb.

 

[Captnorm30]

Thats the claim, yeah. The light i want has six 3W cree LED bulbs, for an advertised 18W draw. Im curious if running that alongside my factory light will give me issues, or put a strain on my stator or battery, prematurely wear something out, ya know?

 

[longdistancerider]

Which CB250 are we dealing with? The early 1970's or the 1990's and later?

 

[Captnorm30]

It's a 1992

 

[Alan F.]

My research says 190 watts, but is that dependent on engine RPM?

 

[longdistancerider]

I don't have the FSM for this model but using the CMX250, Rebel, it shows 190W @5,000 rpm. Yes these are somewhat dependent on RPM however the spec is showing the maximum rate possible. It is still functioning at idle speed, probably in the 75-80% range.
So of the total available you can safely use @80% and have enough left to keep the battery charged. The CDI ignition has very low draw unlike points ignition, figure @5W. So 190W x 80% gives you 150W to use.

 

[Captnorm30]

So bear with me, cuz I'm not skilled in engine electronics. If im understanding that correctly, my leftover wattage at idle (150w), thats wattage that is available, or unaccounted for? What I mean is, with the bike running at idle, and the engine drawing power to run, headlight drawing power, etc, all the normal power draws when a bike is running, after that, I still have 150w to play with before the battery/ stator can't keep up? (Understanding these are specs for a rebel, not the nighthawk)

 

[J-T]

No, you have 150w total to play with after the ignition load is accounted for. If you add up the load from each of the light bulbs, including one pair of turn signals, that will pretty much tell you how much reserve you have. For instance, if all the lights add up to 120w, you have 30w left to run your new lights and charge the battery.

Thread moved to SOHC electrical.

 

[Captnorm30]

Oh ok, I understand now. So I'll find out how much power my stock equipment is pulling, and if the numbers add up in my favor, I'll temporarily wire in my new light, and see how the bike does on a good test ride. Thanks for the input!

 

[Alan F.]

Oh ok, I understand now. So I'll find out how much power my stock equipment is pulling, and if the numbers add up in my favor, I'll temporarily wire in my new light, and see how the bike does on a good test ride. Thanks for the input!

Please post your wattage totals here, I'd really like to know what you come up with.