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View Full Version : H4 globes, run both filaments together?



cjc_td5
3rd June 2019, 02:00 PM
I am planning a rewire of my series 3 to install relays and also bypass a dodgy lucas stalk switch. I was wondering about wiring it such that the low beam ran constantly (when the lights were turned on) and then the high beam just run over the top? So the H4 bulbs would be running both filaments when high beam was running? Will this cook the bulb or reflector in short order? I'm not worried about current draw as I am rewiring anyway.

I'm thinking of using the disused panel light switch on the dash to switch high beam on and off. It is close enough to the stalk to be easily and quickly reached with a finger. Run through a relay of course... Another option is a good old fashioned floor switch.

Cheers,
Chris.

Milton477
3rd June 2019, 02:29 PM
With twice the heat produced by 2 filaments, I recon the smoke will escape somewhere.

Plutei
11th June 2019, 11:29 AM
100W globes are run often enough without problems. If you've got original 7 inch headlights and not cheap plastic ones then you're not going to melt them, so the only chance of damage is to the globe (that I can think of...). Worth a shot I reckon!