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H4 Dual Beam (Running Both at Once) Info Request

1K views 3 replies 4 participants last post by  shinyribs 
#1 ·
This has come up a handful of times lately. I accidently brought it into another thread, and so as to not crap up that thread, I'm starting this one.

I am (and have been for quite some time) of the school of thought that says it's okay to run both beams of an H4 headlight at the same time. Plenty of other people are not. I'm not interested in discussing that here. I've done it to many headlights, and I know where I stand, despite some very persuasive and well-reasoned arguments to the contrary.

Still, I've never seen a single credible primary source (technical bulletin, spec sheet, manufacturer's statement, etc.) supporting either position. (I'm not counting statements that begin with, "I'm an engineer...", unless you're an EE who works for an automotive lighting company designing bulbs and/or lamps.)

Again, I don't want to open a general discussion on the matter, but if anyone can provide me said credible primary source- regardless of what position it favors- I'd be grateful (and will rep you, for the few points that's worth).
 
#2 ·
give me a bit of time. i remember seeing something from piaa and something from silvania about this. the funny part is that they were contradictory. one said it was ok. one said it wasnt. the one that said it wasnt said that it would raise the temp inside the bulb enough to break the glass. the one that said it was ok said only in full metal/glass housings. no plastic. may take me a bit to find it though.

on a side note i have done it and seemed to kill headlight bulbs (only on my bike or in my truck off road though, didnt seem to pop bulbs in a car) i know that is exactly what you said you didnt want in your post haha. but thought id throw it in.
 
#4 ·
The 69-78 SOHC CB750's have hi-lo switches famous for sticking in the middle making both elements burn. You can push past it but its easy to run both beams. I put a relay on the high beam side to take the load off the switch gear and run both beams religiously.

Its kinda nice actually. I can run lo or hi separate or both together that way.

+1 for funky early Japanese switchgear :D

On my chopper I wired low beam to come on with the ignition and just used the stock switchgear to toggle hi beam on and off. It did what Andler mentioned. Worked out pretty good and eliminated a bunch of extra handlebar wires.
 
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