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led headlight bulb problem
matty h - 24/11/15 at 08:09 PM

I recently got some led h4 headlight bulbs for my libra but they do not more correctly.
They are on main beam constantly but when powered straight from a battery they work perfectly.
Dip should have one section of the leds off but they are all on on both dip and main.
Any ideas.
Matty

adithorp - 24/11/15 at 09:06 PM

Sure the 2 lives and the earth are on the right contacts?

matty h - 25/11/15 at 12:25 PM

Yes checked this first.
Matty

gregs - 25/11/15 at 07:43 PM

Grasping at straws but assuming system with conventional bulb works fine and LED bulb works fine direct to battery (which is what I think you've said) could it be something to do with lack of resistance in the relay circuit?

Only system difference I can think of! - could try setting a resistor in series with the bulb and see what that does?

Greg

Adamirish - 25/11/15 at 10:28 PM

quote:
Originally posted by gregs
Grasping at straws but assuming system with conventional bulb works fine and LED bulb works fine direct to battery (which is what I think you've said) could it be something to do with lack of resistance in the relay circuit?

Only system difference I can think of! - could try setting a resistor in series with the bulb and see what that does?

Greg


^^^this.

LED's do some strange things I'm told.(I know less than nothing about electrics) I had an issue with indicator bulbs on my bike. I changed from led bulbs back to normal and they went haywire. flashing way too fast amongst other things. A bit of head scratching, a phone call to my dad(electrical genius) and it turned out, when the previous owner changed the bulbs to led's, he changed the flasher unit too. I put a standard one back on and all was sorted.

He told me it was something to do with the resistance change between the 2 bulbs and the flasher unit. It was way over my head but whatever he said worked.

Chris_Xtreme - 26/11/15 at 08:34 AM

I can't think how a normal relay would care if it was a led or halogen bulb.

You can switch a normal relay with no load on it.

(indicators are different)

Is is something to do with the switching to main beam it cuts the power to the dipped beam? so when you are on your led you loose half the lights? I think this is what would happen in a standard single bulb headlight IIRC.

(Interested to hear if you find them bright enough when you get them working)

DW100 - 26/11/15 at 10:04 AM

I would go with Addi, that the LED bulbs have a different pin out to proper H4 Bulbs.

Are these are an EBAY special from a workshop in china?, if so who knows how they wired them up.

[Edited on 26/11/15 by DW100]

adithorp - 26/11/15 at 12:14 PM

quote:
Originally posted by DW100
I would go with Addi, that the LED bulbs have a different pin out to proper H4 Bulbs.

Are these are an EBAY special from a workshop in china?, if so who knows how they wired them up.

[Edited on 26/11/15 by DW100]


That was going to be my next suggestion; That some 6year old in a chinese sweatshop had set the machine up wrong.

Your earth should be on one of the side terminals (forget which one) and not the middle one but lots of people get it wrong.