The Stovebolt Site Forums The Shop Area The Electrical Bay Dim headlight problem

This one's not strictly limited to stovebolts, but it bears mentioning, as a lot of vehicles can benefit, including our old trucks. Ever notice how a lot of our rides have a problem with yellow-looking headlights that just don't project enough light for safe night driving? Quite often there's a very good reason the lights don't do the job they're intended to do- - - - -series resistance in the circuit. The average headlight circuit has to make it through a BUNCH of connections- - - -from the battery cable connection at the starter, through the ammeter, to the headlight switch, to the dimmer switch, to the junction block at the core support, and finally to the headlight connector. Then it has to make it back through a convoluted ground circuit to find its way back to the battery. Just a tiny bit of resistance at each connection steals a little voltage from what gets applied to the headlight filaments. Series resistance adds up, like putting pebbles in a long distance runner's pockets a few at a time and expecting him to carry all that extra weight for miles. He's going to get tired, eventually.

My Gold Wing motorcycle is a good example- - - -sometimes I think I need to use a flashlight to see if the headlight is on. I even bought a new halogen sealed beam bulb and installed it, with no noticeable improvement in the illumination it provides. Next step- - - - -relays! I'm going to run heavy wires from the battery posts, (hot and ground) to the fairing, and into the headlight nacelle, and install one relay for high beam and another for low, triggered by the wires from the dimmer switch that used to power the filaments. Since the bike has no on/off switch for the headlight other than the ignition circuit, I don't have to worry about turning the light on and off- - - -engine running- - - -headlight on- - - -sort of idiot-proof!

This setup should allow the headlight to receive full charging system voltage and the lowest-resistance ground possible, without having to worry about sneaky parasitic losses along the way. It's an easy circuit to wire, and the difference is usually very noticeable- - - -particularly on a 6 volt system where even small voltage drops make a huge difference. There are dozens of small Bosch-style relays available on Ebay- - - -with connectors, dirt cheap!
Jerry

Thanks, Jerry. Nice explanation.

My guess is that a similar "losses" in the grounding circuit/connections?

Grounds are even sneakier than losses on the hot side. Since most vehicles rely on body and/or frame metal to provide most or all of the ground circuit, decades of rust, loosening of rivets, salt, and other contaminants can sneak into places on the ground side that makes it difficult if not impossible to pinpoint where the voltage loss is happening. It's hard to have too many good grounds- - - -preferably good-sized wires with clean, tight, bare metal connections between the engine, bed, body, and frame in several places. Rubber engine and body mounts DO NOT conduct electricity!
Jerry

My headlights work fantastic since I installed a heavy duty headlight harness from LMC. It has two 30 amp relays and is a plug and play harness, for TF trucks. They have one for the AD trucks also. I had installed halogen headlights and they were overheating the stock circuit breaker on the headlight switch. The old stock headlights worked OK, but were dim , and it was not much fun driving on Calif freeways after dark. No more! It's like having two search lights on the front of my truck. I have them adjusted down and alittle to the right, so as to not blind oncoming drivers. Low beams are nice and bright too.

Did the Gold Wing come with dim lights? I would expect some re-engineering would be required for British bikes (lighting by Lucas, prince of darkness), but not a Honda.

A 30-something year old bike (1981) has just developed some electrical gremlins over the years, compounded by a rats' nest of wires up front involved in fitting the Vetter Windjammer fairing. I'm slowly improving the electrical system with extra wiring, and a multi-position fuse block, relays, power jacks for my Garmin, sound system, etc. I'll be adding a "Big Boy" air horn and possibly some parade strobe lights soon- - - -gotta look good on the Patriot Guard rides I participate in. I'll have a small extra battery for the strobes mounted in a compartment in one of the saddlebags to take the load off the main battery, with a solar panel maintainer to keep it charged.
Jerry

Yes, it's strange how the gremlins creep in as a vehicle ages. In it's old age, my 1980 C20 developed an odd problem; every once in a while the wipers would sweep the windshield. Just one sweep and it wouldn't do it again for a week or so. It would do it in the summer when it hadn't rained for weeks. My wife said the truck was haunted - good as an explanation as any - I knew that tracing a seemingly random event was pretty well impossible. Back in 1980, intermittent wipers was an new extra cost option; I guess GM still had some flaws to work out.

Voltage spikes that an older system would ignore do weird things to solid state electronics. In the early 1980's I was teaching a 2-year professional level auto mechanics course at a Tennessee state trade and industrial school (last stop before a permanent spot on the welfare rolls for a lot of my students) and teaching sophisticated electronics to people who were GED-level on the education scale or just slightly above was a challenge. That's about the time auto electronics started getting very complex- - - -computer-controlled carburetors, delay wipers, memory seats, electronic climate control, electronic cruise control etc. After 8 years of fixing autopilot and compass systems on B-52's, all that was pretty basic stuff for me, but the auto industry was in a panic!
Jerry