Headlight flicker with LED's

[Alexander D.]

(Purists may cringe now)

I recently installed LED headlamp bulbs in H4 glass housings in my '67 to replace the dim incandescent bulbs. The stock headlamps are pretty dim, especially when driving at speed on a dark road.

I bought an H4 halogen lighting kit from Octane Lighting (includes 4 glass housings, and 4 H4 halogen bulbs). I then swapped out the halogen bulbs for Auxito LED's,

The improvement in lighting with LED is remarkable! Night time driving is much safer, as I can see much better down the road.

But, one little problem remains. The headlights will 'flicker' momentarily whenever I apply another electrical load (e.g. brake lights, turn signal, power window, etc.) The flicker lasts only a fraction of a second, so isn't really a safety issue. But it's a bit annoying so I'd like to figure out how to eliminate it.

My understanding is the LED's draw less power than the stock incandescent headlamps.

What is causing the flicker? Do I need to install relays or something along those lines to eliminate this?

Thanks.

[Mark E.]

Re: Headlight flicker with LED's

The headlamp switch has an internal thermal circuit breaker to protect the circuit from overload. Flicker is a common symptom when this trips.

A remedy is to install relays for your LED headlamps.

[Stephen L.]

Re: Headlight flicker with LED's

Led's are more sensitive to voltage fluctuations than incandescent bulbs. The "flicker" could be caused by the response of the voltage regulator (mechanical) to changes when additional loads are placed on the system as in turn signals flashing etc. Check to see if you see small quick fluctuations in your ammeter at the same time the Leds "flicker" A solid state regulator might solve your problem........
As you may have observed, LED turn and brake lights on new cars have much faster response to "off/on" than incandescent bulbs.

[Alexander D.]

Re: Headlight flicker with LED's

Led's are more sensitive to voltage fluctuations than incandescent bulbs. The "flicker" could be caused by the response of the voltage regulator (mechanical) to changes when additional loads are placed on the system as in turn signals flashing etc. Check to see if you see small quick fluctuations in your ammeter at the same time the Leds "flicker" A solid state regulator might solve your problem........
As you may have observed, LED turn and brake lights on new cars have much faster response to "off/on" than incandescent bulbs.

Hi Stephen,

Thanks for your reply. I got around to checking and yes, I do see small quick fluctuations in my ammeter, but these happen anytime I apply a load to the system (e.g. turn signals), not just when the headlights are on. If the headlights are on, the ammeter fluctuation coincides with the LED headlamps flicker.

Where do I get a solid state voltage regulator? Is there any other downside to installing one of these in place of the stock regulator? Will the solid state unit fit inside the "Delco Remy" black metal voltage regulator housing?

[Alexander D.]

Re: Headlight flicker with LED's

The headlamp switch has an internal thermal circuit breaker to protect the circuit from overload. Flicker is a common symptom when this trips. A remedy is to install relays for your LED headlamps.

Hi Mark,

I doubt the headlamp switch thermal circuit breaker is tripping, because the LED headlamp bulbs draw 26 watts per bulb vs. 55 or 60 for the stock incandescent bulbs. Before I put in the LED's I had H4 halogen bulbs on the car. With those, if I ran the high beams for too long this would trip the headlight thermal circuit breaker. The symptom would be the headlights would pulse off for 1 or 2 seconds, then come back on in succession as the breaker tripped and reset when it got cool enough. What I get now is a momentary 'flicker' of the LED's whenever placing any added load on the electrical system. The headlights do NOT go out, they just flicker briefly.

You mentioned relays. How would these help? Would I need to install one relay per headlamp bulb (i.e. 4) ?

Thanks for sharing your know how.

[Stephen L.]

Re: Headlight flicker with LED's

Alex,
A solid state VR is available on EBay among many other parts houses.... They will "fit" generically, but will be discernable from the original if you are concerned with date codes etc. Cost about $20

[James G.]

Re: Headlight flicker with LED's

Some people remove the solid state components and install them in an original dated base from an original VR.

[Dereck S.]

Re: Headlight flicker with LED's

Alexander,
Can you confirm you purchased the Octane 9810 four lens Halogen kit? Also, what Auxito H4 LED bulbs did you use in the high/low positions? Did this low beam solution result in blinding oncoming drivers? The Vintagecarled.com solution is expensive and only German Hella lenses are available in VCM3. However, they are positively rated by C2 owners.
Thanks

[Frank D.]

Re: Headlight flicker with LED's

Alex,
A solid state VR is available on EBay among many other parts houses.... They will "fit" generically, but will be discernable from the original if you are concerned with date codes etc. Cost about $20

The "quick and dirty" conversions don't use the original base and are detectable.
The ones I have built are not detectable - and my 63 conversion passed regional judging:

Just be aware vis a vis LED headlights, LED bulbs installed in housings not specifically made for a specific brand can be illegal in some states (maybe all) and there have been law suits, that is one avantage of the VintagecarLEDs - they are complete package with housing and bulbs with components that ensure good dispersion and focus height. (Pictured below). Notice in the last pic the difference in the top and bottom half of the LED housings in the low beam positions; designed to prevernt blinding oncoming drivers.

[Dereck S.]

Re: Headlight flicker with LED's

Frank
Do the VCM3 low beams in your 63 have the German Hella lenses? Vintagecarled.com doesn't have the classic lenses in stock. The Hella VCM3 are $57 off today. I'm concerned that they are too modern looking. Thoughts?
Dereck

[Frank D.]

Re: Headlight flicker with LED's

I bought VERY early versions of the VCM3 offerings, and they are pretty modern looking and in no way resemble a T3 lens.

[Ralph E.]

Re: Headlight flicker with LED's

Does the headlight flicker happen with all LED headlights?
Will the Holley LED's work without the flicker?
https://www.holley.com/brands/holley_retrobright/

[Jim L.]

Re: Headlight flicker with LED's

Led's are more sensitive to voltage fluctuations than incandescent bulbs. The "flicker" could be caused by the response of the voltage regulator (mechanical) to changes when additional loads are placed on the system as in turn signals flashing etc. Check to see if you see small quick fluctuations in your ammeter at the same time the Leds "flicker" A solid state regulator might solve your problem........
As you may have observed, LED turn and brake lights on new cars have much faster response to "off/on" than incandescent bulbs.

Stephen has nailed it. It takes an electro-mechanical Voltage regulator a finite amount of time to respond to sudden changes in load. In that interval during which it is re-adjusting the alternator output, the system Voltage will be less than normal if the load increased and greater than normal if the load decreased.

A relay won't help the issue at all.

Converting to a solid state Voltage regulator with its inherently quick response time might mitigate the problem somewhat.

If, after converting to a solid state VR, the flicker is still noticeable, you'll need to position a means of energy storage near the headlights to momentarily fill in the gap while the VR and alternator recover from the change in loading.

A capacitor, a huge, honkin' capacitor is your means of storing electrical energy. My back-of-the-envelope S.W.A.G suggests that a capacitor of around one Farad in value would meaningfully reduce any residual flicker if a solid state VR doesn't do the trick. Fortunately, such capacitors are readily available from suppliers of high Wattage car audio systems.

Connect capacitor (+) to the headlight power wire as close to the headlight as practical and capacitor (-) to the headlight ground connection.

Good luck.

Jim

[Frank D.]

Re: Headlight flicker with LED's

Most LED headlight bulbs are designed to operate over a broad range of voltages, some from 9V-32V, so nearly anything an alternator puts out should work if properly regulated. Mine were flcker-free using a solid-state V/R.

[Jim L.]

Re: Headlight flicker with LED's

Most LED headlight bulbs are designed to operate over a broad range of voltages, some from 9V-32V, so nearly anything an alternator puts out should work if properly regulated. Mine were flcker-free using a solid-state V/R.

From the OP's symptoms, it's obvious that his LEDs change their light output as a function of their operating Voltage.

A solid state Voltage regulator may help the OP work around this characteristic of the lamps he has. If not, then he needs to add a large capacitor right at the headlights to smooth out the Voltage transients from his car's charging system.