Quote:
Originally Posted by aesmith
I'd be interesting if you measured that. Low resistance isn't easy to measure with DIY equipment, also I'm not entirely clear how you'd sum the parts that are common with other loads or even between the two headlights.
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If I get some spare time this afternoon I might do it. I’m qualified as an electrician (not that I do it as a business) so I have a multi function test meter that will measure down to small parts of an Ohm. I don’t think there would be much of a problem with a dead test between the two battery terminals and the two live terminals of the H4 block connector. I’d have to check the wiring diagram, but I’m pretty sure the two headlamps are wired in parallel from the same two lives (looped in and out of the first to the second), so one only has to measure the impedance to the last one as the difference is just a couple of feet of wire (just as one does on a radial circuit in a building). I suspect the biggest losses will be at the two movable switches (key and high/low beam), but as long as the impedance of the whole is very small compared with the bulb the voltage drop to the luminaire will be small.
You are right that the situation would change if another large load was applied to the battery - but the only one that would apply on a standard set up would be the starter, which I think I could ignore for the purpose of this exercise (one would expect the lights to dim when operating the starter).
If I get round to it this afternoon I’ll post the results.
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