My headlamp stopped working on low beam so assumed blown bulb. I ordered a 55/60w halogen one as replacement. Turns out it was a dodgy switch bulb was ok. 12 volts system
Put the halogen one in very bright on main beam but quite dim on low, have cleaned all the connectors earths etc but still the same, fine with the original (35w I believe). Two questions really, will the wiring withstand the extra wattage ( self made harness from AO’s kits, modern reg/rect) and any ideas why the halogen is dim in low beam. Quite happy to stick with old bulb but also keen to use the new one.
Thanks
Pete
Are you sure...
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Metered
Checked with a multimeter, on the two sprung contacts on the bulb retainer, get 12v to earth on one pin, nowt on other, flick dipswitch and other pin live and first one now dead. No condition is sending 12v to both pins simultaneously. It works fine with the old bulb on dip and high, just the dip is is dim with halogen lamp. Thanks
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Mr Brown
I would think your nice new connections to rear of your QH lamp are wrong. With H4 the centre is NOT the earth. Checking with a multi meter for 12V around such a lamp will lead you astray as you can read 12V both sides of the lamp (with a non working lamp) and the earth is lost. Electricity -funny stuff.
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Headlamp bulb problems
I changed to LED headlamp and tail-lamps from Paul Goff and can now be seen at all times with the headlight on, no load on the dynamo, (early Dommie) and no wiring worries. You need clean connectors and a good earth as the currents are so tiny.
Classic Dynamo Regulators also are very helpful, so you can put the original regulator on the shelf and give your dynamo or alternator and the battery a better life.
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Test with a battery
Take your lamp cap with bulb inserted and test on a fused supply from your battery. If both filaments light independently you have a wiring issue not a bulb issue.
Current consumption on 12 Volt is roughly 3 Amps for original bulb and 5.4Amps for you High Beam Tungsten filament, 4.8 Amps for your low beam.
Your cabling is, I guess is minimum 1mm Sq which has a capacity of 16 Amps. Check your battery AH and you have sufficient charging to maintain that load (plus rear lamp) on a long journey....
J
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... you have the connections right? You may have swapped the earth / dip connectors in which case you'd have both filaments powered in one state and a poor earth in the other.