voltage at headlight???

[graybird78]

Hello to all.
I had posted a while back about voltage at headlights. had read interesting article about using relays to get brighter headlights. did some testing today with my bike.got some interesting readings.first i made sure my battery was fully charged. started bike up and checked voltage at headlight. had 11.5 to 11.8 volts. voltage did not go up with engine reved. so proceeded to take seat and tank off for better access. checked voltage at battery got 14.2 volts w/engine reved up. checked voltage going to rlu still 14 volts. checked voltage coming out of rlu about13.8. checked voltage at fairing wiring connector still 13.8.unplugged headlight got 13.8 volts.plugged light back in back down to 11 volts. new bulb. double checked all readings.all the same. now i wired in a relay. all readings the same except now i have 13.8 volts at headlight. light looks brighter. i don't see how a dvom could be lying to me. even double checked my readings again.still the same 13.8 volts at headlight with relay installed. all readings were at 3000rpms. before installing relay and after. any insight or feed back.don't think i left anything out .

[TopCatGr58]

Hey Graybird78,

How did you measure the voltage with the headlight bulb plugged back in?? My DigVoltmeter will give me funny readings if I don't have good contacts with the wires and the test lead probe tips!

SO, are you saying that you installed a direct tap from the battery going thru the relay to the headlight, and then the 13.8 volts was found WITH the headlight bulb plugged back into the socket!? Did you use a new headlight socket, or the OEM?

The lower voltage could have been corrsosion in the socket, the wires to the clips in the socket? That could lead to a dimmer bulb, and maybe all it needed was a bit more cleaning up of the socket/contacts!?
T.C.

[graybird78]

hello topcat.
I measured voltage at headlamp connector with headlamp on and 3k rpms. 11volts. with standard 4 pole relay installed and using power from battery to relay to power it up showed 13.8 volts. used new 9003 bulb i installed 2 wks ago. headlight was plugged in for all tests.did clean all contacts prior to tests.

[Dennyz]

The drop is most likely due to the RLU (Reserve Lighting Unit). It places a small amount of resistance in line with the head light and measures the voltage drop across the resistance. This is how it knows if the head light is working. I imagine that it is possible for some RLU to be more resistive than others.

I defeated the RLU for just this reason. I figure it makes more sense to get all the light I can over the need to be notified if my head light burns out. To me, it is kind of like wearing a band aid on your arm in case you cut yourself.

I went one step further and put relays between my head light and battery with a large gauge wire from the battery to the relays. It takes a relay for each element (high and low beam). I use 30am automotive 12v aux lighting relays. These relays are an over kill but inexpensive.

Defeating the RLU also enables both elements to be on in high beam. I notice a much brighter high beam and very little dimming of the low beam at idle. I feel my low beam is brighter also.

[graybird78]

hey their denny. have you had any problems with the relay set up. just want to get brighter headlight . figured would make agood winter project.

[pathfinder]

Please correct me if I'm wrong. But isn't the headlight made to run at 12V or less? If you over volt the light will it not burn out much faster?
I made my own rectangular headlight from an automotive plastic 9004 replacement. I took apart original headlight by heating the plug-in stub so it dropped inside then heated the glass around the edge of the metal backing and removed. Used a propane torch. I then cut a 2.5" circular hole in the back of the metal housing. This way you have original headlight adjusting tabs. The new plastic replacement was a little to high to fit into the metal back so I spread it with a Black & Decker Workmate. The new plastic fits in now just fine. You will need a chrome automotive headlight ring to clamp all this together.
Now you have a H4 replicable bulb type headlight that is much brighter than original. With no wiring changes. I will admit it sticks out about 1/4-3/8" farther than original but boy is it bright. This all fits very tight, I had to file down and bend the beauty ring ID so that the adjustment screws would work. If it burns out on the road, just replace the H4 filament from any auto parts store or Wal-Mart. Also once you adjust the headlight you should never have to do it again. It still fits in the original bucket or fairing mount. Looks good and much brighter.

[Dennyz]

The relays have worked fine. I’ve had them in for a couple of years. The standard headlight bucket is large enough to fit both relays inside the bucket, right under the mounting bolts. That way all that is needed is a power and ground source run into the bucket. I purchased an automotive headlight plug and wired it straight to the relays and wired from the relays to the wiring harness headlight connector. To get both elements on at the same time in high beam, I placed a diode between the high and low beam wire (yellow & green). I found that using the 90/130w bulb does not need both elements on (15amp current draw), but it does help the stock 55/65 bulbs.

Prior to adding the relays and defeating the RLU, the 90/130 would cause the wiring in my headlight bucket to get very hot and dim significantly at idle. I found the RLU will not allow the diode trick to work.