Earthing problem with headlights

Sanjøy · Post by **Sanjøy** » Sun Apr 15, 2007 6:18 pm

One lamp off and driving light on 50% when lights are on. Worth tracing it all or simply recabling ? Could this be caused by cable degrading after running rally bulbs for a few years, the connectors have melted.
Clam will probably be off for other things.

Rich H · Post by **Rich H** » Sun Apr 15, 2007 6:46 pm

Rewire then if clam coming off. You could also mount your horn properly!

Sanjøy · Post by **Sanjøy** » Sun Apr 15, 2007 8:21 pm

Never had any complaints

woody · Post by **woody** » Sun Apr 15, 2007 8:46 pm

I had connectors in the same state as yours. I chopped them off, soldered new ones ones from a scrapyard, wrapped the cables and they've been fine ever since - with uprated bulbs.

Sanjøy · Post by **Sanjøy** » Sun Apr 15, 2007 8:49 pm

What causes the melting ? Head off the bulbs or the actual metal in the connectors getting too hot due to crappy connections ?
Thinking the latter as we had an issue at work with some HV power cables getting hot due to poor crimping. Thermal imaging camera showed it up as the fault, tres cool.

woody · Post by **woody** » Sun Apr 15, 2007 8:54 pm

One of mine had moisture in and around the plug when it was melted. At the time i put it down to the plug not sitting in the protective boot TBH.

Rich H · Post by **Rich H** » Sun Apr 15, 2007 11:23 pm

I would imagine it would be down to the bulbs themselves getting hot. I would have thought that if the resistance was that high at the connector it would have packed up ages ago.

robin · Post by **robin** » Mon Apr 16, 2007 8:29 pm

RICHARDHUMBLE wrote:I would imagine it would be down to the bulbs themselves getting hot. I would have thought that if the resistance was that high at the connector it would have packed up ages ago.

Maybe yes, maybe no.

W = I*I*R

50W bulbs at ~15V are taking on the order of 5A (because they're rated at 12V, I think, so when you crank up the voltage, the head lights get brighter and take more current). A 1 ohm resistance would then dissipate 25W (that's a lot, by the way) but would also drop 5V which would probably dim if not completely kill the headlights.

However a 0.1 ohm resistance would still be dissipating 2.5W (still enough to make it hot) and would only drop 0.5V, i.e. not enough to have any impact on the bulb operation.

Cheers,
Robin

Rich H · Post by **Rich H** » Mon Apr 16, 2007 10:48 pm

electric wires contain smoke, it's bad if any escapes....

robin · Post by **robin** » Tue Apr 17, 2007 7:47 am

RICHARDHUMBLE wrote:electric wires contain smoke, it's bad if any escapes....

LOL - it's OK if some leaks provided you have a smoke pump to keep putting new smoke in ...

Robin