LED strobes not working together?

[Alex G.]

On my TB20 there is a JPC LED strobe on the tail and today I’ve installed 2 Whelen 650e LED strobes for the wing tips.

Since my G1 TB20 didn’t have a dedicated wire harness for the wing tip strobes, and I wanted them to start/stop at the same button press in the cockpit, I’ve connected them to the existing tail strobe (at the wire that feeds the tail strobe inverter).

Now there seems to be an issue, because whenever the tail strobe flash combine with the flash of the wing tips, the tail strobe momentarily turns off. Sometimes in the middle of the flash, if it happens for the wingtip strobes to start flashing just at that moment. When the pulses are intercalated (out of sync) there is no issue, both run ok.

Is there an issue with voltage drop when peaks combine or grounding that may be somehow corrected?

The system is a 12v one, the wingtip Whelen 650e draw 3.4 amps combined (peak) with no inverter needed, and the tail JPC one that uses an inverter draws 6.2 amps (peak). Actually it is rated at 75W/12V and hopefully I did the math correctly.

The positive wire that feeds both seems to be an AWG20 or AWG18 standard copper multicore twisted cable. The negative wire that feeds both is taken from the aircraft chassis.

Any idea on how to solve this? Thank you!

 

[MooneyDriver78]

What’s the peak power draw? My Whelens would pull ~11amps, I didn’t sync them because I like them that way and I thought the pulse might cause radio noise. You can put a voltmeter on the tail connections and look for a voltage drop, LEDs require a minimum voltage


Tom

 

[Alex G.]

Peak power draw is 3.2 for the Whelen, combined with 6. 2 for the JPC. The engine was not running, battery power only with no alternator.

I will try to measure the voltage tomorrow.

 

[Alex G.]

I managed to power the aircraft from a 100 amps external power source, with no change. When they overlap, only the wingtip strobes work.

However, as soon as I press the avionics button to start all the equipment, something strange is happening. Somehow, the 2 strobes magically always stay out of sync and flash one after the other, with no more issues.

I did the test several times. Avionics on, strobes always flash one after the other and work with no issues. Avionics off, the strobes timing starts to shift and, as soon as they overlap, the tail one is not flashing. Avionics on again, magically they somehow sync and flash only one after the other, no issues.

This is driving me crazy! The 2 strobe systems have no sync connection and do not communicate in any way. How on earth starting the avionics will always get them to flash one after the other?

The only thing that happens when I start avionics is a higher overall load on the battery, which should make things even worse...

I don't mind the current setup, since I always fly with avionics on, however I don't have any idea what happens, if any of you do, please let me know!

 

[bnt83]

Sinple test, disconnect the connector from one wing tip and see it if still does it.

Bypass the cockpit switch and see if it still does it.

Maybd power both 650s using a test wire back to the battery eliminating the circuit through the switch.

Continue on with troubleshooting till identifying the problem.

 

[asicer]

Does it behave the same when the engine is running vs when you're only running on battery? When running on battery only, the LED strobes on the Skycatcher would tend to blink 2-3 times and then stop. After starting the engine, and running up the RPM they seem to return to normal again.

 

[MooneyDriver78]

My Mooney navigation LEDs would come on when I put a charger on the battery. Found out that they connected the navigation lights in a way to automatically dim annunciator lights when nav lights were on. You might want to get electric schematics for your plane.


Tom