Led/ tungsten bulb inter-action?

I noticed no such effect with mine. After another club member said he couldn’t see my brake lights and the headlights were pretty useless anyway I made the switch to LED. A revelation. I left the rear fog, reverse and number plate lamps as standard.

 

Sort of related, but might explain what you're experiencing.

I replaced all exterior bulbs with LEDs (US spec 328, no rear fog lamps). My turn signals wouldn't work. Well, they worked, but both the left and right were flashing at the same time and very rapidly when I indicated left or right. I believe the relays don't like the low resistance of LEDs. I added resistance back into the feedback by going back to incandescent bulbs only to the front indicator lights. (I didn't want to splice in dummy resistors.) That corrected the L&R issue, but they still flashed rapidly like strobe lights. I replaced the OEM flasher relay (under the steering wheel) with a variable rate LED compatible flasher relay to dial in the flash frequency. Both problems solved and looks fantastic. No issues with low or high beam with my LED headlamps.

 

I did all LEDs. You just have to replace the flasher relay for one that works with LED

I used this one:
https://www.amazon.com/dp/B0B2QM9CP5?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_3

 

Good day Michael,

Although your battery/charging system has sufficient energy to supply the lighting circuits, you are not considering that it takes time for the energy source to reach the electrical load. This energy transit time is affected by a wire's inductance which is a parasitic electrical property of the wire, its length, diameter, etc. Adding to the inductive effects of the wire, the majority of auto LED lights use very basic drive circuitry (series resistor) and so any variations in the electrical voltage as seen by the LED light will result in fluctuations in the light emitting from the LEDs. Because Auto LEDs are designed to meet a price target, their design and components used are typically bottle-of-the-barrel parts... and so issues like flickering, low reliability, running much hotter than they should, etc will result.

If the flickering is really problematic, you could add a sufficiently sized capacitor close to the LED light source and this will provide a suitable amount of energy storage when demanded by the LED light. Ideally the capacitor should be places as close the LED light as possible, but this may not be achievable.

I hope the above provides an answer to what you have experienced.

Cheers,

Sam

 

Good day Michael,

You are most welcome. Once you dig deeper and move past the usual or mainstream electrical familiarity, you will find some very interesting and fascinating details about the physical nature of electricity/electronics/magnetism (e.g. electromagnetics), etc... and at times explains some of the oddities we see at the macro level. Adding to all of this, the core understanding of it all dates back to the 1800's with pioneers/scientists discovering all of this with some very primitive (by our standards of today) and rudimentary equipment/tools. The handful of these people were truly remarkable and I am always in awe and humbled that my knowledge is only because of them. But, I digress...

LED lights and especially those used in high brightness (HB) applications can have all sorts of drive circuits with varying levels of quality, reliability, etc. Consequently, the exact cause can be variable and so the remedy can also be different (capacitor with other bits, etc). Ideally, one would analyze the voltage/currents as seen by the LED light using equipment a step or two higher than a multimeter (e.g. oscilloscope)...and then formulate the appropriate corrective circuit and components needed. That said, one could simply try a cap or two placed across the voltage input to the LED light. Adding a Cap will not hurt anything, but does have limits because of Cap's own characteristics. You could try adding a Cap of say 100uF Electrolytic (minimum rating of 25V, but I would go with 35V to allow for some extra headroom... remember Electrolytic caps are polarity sensitive!) and note if things improved. If not, then you could go to say 470 uF. I would not go higher, as larger sizes can cause other issues. If the 100uF to 470uF has had no effect, then there is something else going on which could be related to the LED's drive circuitry... which would imply a very basic/crappy design. Just to rule out any LED drive "switching" noise, you could try adding a 0.1uF 50V Ceramic cap across the Electrolytic cap. This small sized cap has a different purpose and is used to filter higher frequency electrical noise which can be present on the voltage input. This is why scoping the voltage, etc would be best... as then you can see actual data of the changes and not rely upon your eyes seeing any flickering.

Cheers,

Sam

 

I don't have a 328 and I may be way off here, this is just pondering, but could it be the logic? I say this because on the vehicle I own that has fog lights it will go to low beam when you switch them on because you wouldn't use high beams in fog.

 

Yes my example is my Land Rover so it may be a UK thing.

 

Good day MIchael,

Depending what is going on, a regular scope may not show the issue, or more accurately you may not "see" the issue depending upon what it is. Modern scopes have all sorts of additional functionality including the ability to capture transient events which can later be reviewed. Also, some scopes include features that are found in other specialty instruments such as performing a basic spectral analysis of the input which may also provide some insight. All of this requires experience and familiarity with the scope in order to use it for various testing needs. Secondly scopes have a variety of probes that must be selected based upon what you are looking for. Scope probes can and do affect the circuit under test and so this has to be taken into consideration. Simply hooking up the scope will certainly provide you with a waveform showing a time varying signal, but to identify and track down a specific issue requires a lot more effort and skill.

Also, I do see that there are two different issues you are looking at... The first is the flickering, which is what I am talking about, and the other deals with operational issues if if other lighting circuits are turned on. These may or may not be related, but other diagnostic efforts would be needed to determine if they are indeed related.

Cheers,

Sam