LED light issues.

Greg Bockelman

Greg Bockelman

Touchdown! Greaser!
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Greg Bockelman
In the interest of reducing the current draw on my 25 amp generator, I have replaced all of my lightbulbs with LED replacements. I have a Whelen nav/strobe combination and my panel lights are dimmable with an appropriately compatible rheostat. When I turn all the lights on an “interesting” thing happens. My panel lights dim in sequence with the strobe flashes.

Full disclosure here: this was on the battery charger only. I have not gotten to the point of starting the engine and putting the generator on line.

When I talked to the Whelen rep about it, he was stumped. He had never heard of such an issue.

So, any ideas how I troubleshoot? I have two thoughts. First being that since this was only on the battery charger, maybe the voltage wasn’t enough for the current being drawn. This seems plausible to me.

Second thought, and this was the reps thought, is that the quality of my panel LEDs is lacking. If that is in fact the case, how do I go about finding the best quality dimmable LED panel lights?
 
Who knows what the charger is throwing into the system? If it were my plane, I'd try running it up and see what happens. If the result is the same, perhaps you should check all your grounds. I've often been told that bad grounds are the first place to look for electrical gremlins.

What do you have now for panel lights? Bulbs? Strips? Rings around instruments? More info would be helpful.
 
Greg, in your test, are you powering the plane's electrical from the main battery? You mentioned a battery charger but not a battery, so I'm wondering. If it's just a battery charger without the main battery being connected, then that's a problem with your testing setup because a battery charger can only put out a few amps, depending on the model, whereas a battery that's intended for starting the engine can put out a lot of amps.

My Whelen LED wingtip strobe/nav lights definitely consume plenty of amps when the strobes flash, as I can see the needle move noticeably on my analog current meter.
 
Hi Greg. I had a similar issue years ago when I tried to replace my panel lights with LEDs. Sure seemed like a no lose situation. Med to high intensity setting appeared good. Under low light conditions at low dimmer settings, any load/voltage changes on the electrical system (ex periodic strobes) resulted in the panel LEDs dimming/brightening in sych. My dimmer system is 1980 Piper PA28 transister technology. I believe with LEDs installed, I reduced the load on the dimmer circuit sufficiently to get it out of the original design/linear range to make it very sensitive to supply voltage changes. I put the incandescents back in.
 
Definitely get the plane out of the hangar and run it at night first before flying it.
Some led will cause noise/static and not be compatible in a aircraft. I think the panel lights are most sensitive in this regard. Also I found some design led bulbs are not the right light distribution pattern if you know what I am trying to say. Especially in the panel.
 
Greg Bockelman said:
Full disclosure here: this was on the battery charger only.
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Are you using the charger as a power supply with no battery installed?

Are the panel lights and strobes on same circuit?
 
NoHeat said:
Greg, in your test, are you powering the plane's electrical from the main battery? You mentioned a battery charger but not a battery, so I'm wondering. If it's just a battery charger without the main battery being connected, then that's a problem with your testing setup because a battery charger can only put out a few amps, depending on the model, whereas a battery that's intended for starting the engine can put out a lot of amps.
Click to expand...
I don’t have a battery in it just yet. This is where my next troubleshooting was going to go, but that will be awhile yet
SoCal 182 Driver said:
Who knows what the charger is throwing into the system? If it were my plane, I'd try running it up and see what happens. If the result is the same, perhaps you should check all your grounds. I've often been told that bad grounds are the first place to look for electrical gremlins.

What do you have now for panel lights? Bulbs? Strips? Rings around instruments? More info would be helpful.
Click to expand...

Bell206 said:
Are you using the charger as a power supply with no battery installed?
Click to expand...
Yes, which most likely is the source of the issue.
Bell206 said:
Are the panel lights and strobes on same circuit?
Click to expand...
No, but they share a common ground.
 
A battery charger can never be used as a power supply. Using one in that manner is a good way to damage your electronics. At least put a battery in the circuit. Could be a very expensive mistake in a aircraft.
 
That doesn’t sound right, is it all on the same circuit breaker? Put the strobes on a separate circuit breaker. Start up the airplane. I don’t think I’ve tried the strobes with the panel lights on while only on the battery before. You’ll want to make sure you can disable the strobe light if this happened in flight. Carry a red light flashlight as a backup as well.
 
The symptom you are describing is the same thing I've experienced with multiple dimmed devices from instruments, to interior lighting. When dimmed low these experience enough input voltage fluctuation to cause flickering.
 
Gary Ward said:
A battery charger can never be used as a power supply. Using one in that manner is a good way to damage your electronics. At least put a battery in the circuit. Could be a very expensive mistake in a aircraft.
Click to expand...
This. ^^^

I know you've got this, Greg, but for anyone else thinking of trying this approach, especially with a "smart charger", the charger can be trying to run anything between a charge profile to a float profile, possibly varying the voltage to attempt to maintain a constant current, or anything in between when a battery is not in the circuit, which is not what our electronics want to see. Per image below.

The charger may also generate a significant amount electrical noise, depending on how the switching circuit is set up (and how much one paid).

algorithm-pbchar-1.png
 
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