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Landing Lights Causing Reboot

sglynn

Well Known Member
I'm having an electrical issue I hope someone has experienced and knows the solution. I'm doing the final panel install now and testing. Lots of things work, but when I turn on the landing lights the audio panel, radio and sometimes the EFIS reboot. Turning on the lights is causing a temporary electrical power drain. I can see on the Garmin 430 it goes into no power screen for a second before it fires up again. If I leave lights on everything comes on and stays on fine. The wings aren't attached to fuselage yet so I can test each wing separately This power drain is happening on the left wing only. The different between the wings is the right wing, which works fine has a servo with a ground that goes all the way back to panel. I'm using a Control Module like VP-X. Lights are locally grounded. If I isolate the right wing the lights still work so they must be using the servo ground. When I isolate the left wing, lights don't work. There are only local grounds in the left wing, so when I disconnect it from fuselage there is no ground. But it is this wing that is causing the power suck that reboots avionics when ground to fuselage is attached.

So, what can cause a power suck for an instant?

I'm using a power supply 14.2V good to 30 amps. I'm seeing less than 20amps. My lights are GE bulbs they suck 5-8 amps. I'm thinking something with grounds.

Ideas?
 
Either your power supply is weak or else there is a bad connection someplace. Or there is high resistance in the Control Module, which is equivalent to a bad connection. The bad connection can be in either the negative (ground) or positive side of the circuit. Use a voltmeter to find the voltage drop. The greater the load, the easier it will be to find the voltage drop. In other words, leave the lights on. You could even add additional heavy loads.
 
The landing lights you are using are a huge load, and a lot more inrush current that your listed running current. You are simply exceeding the capacity of the power supply.

Try this - run the power supply with your charged battery both on line. The battery will provide the added inrush current.

Better yet - go find LED replacement landiing lights. I did a test of some landing lights (fractional aircraft bulb lights) and found a variety of after market SUV LED lights to be much brighter, draw a fraction of the current and relatively cheap.

Carl
 
As mentioned by others, try using a fully charged battery for your power source. You could even run some jumpers from your automobile's battery. A battery provides a reservoir of power and can absorb and dampen an instantaneous power spike. If you have strictly been using the stand-alone power supply it has no stored potential in the system.

Sometimes when switching a high-amperage circuit the switch can arc across its contacts due to the instantaneous spike. The inside of the switch becomes like a spark plug firing. This is why diodes are added to starter and master solenoids to eliminate the arcing, saving the contacts. So whatever solid-state bus device you are using, make sure it is designed to clamp large spikes during switching, like the diodes provide for analog switching in a conventional bus. Just one more thing to investigate.

It is very interesting that you have been able to isolate the spike to the left wing.

Jim
 
Use the battery

Thanks, it worked when I put the battery back into the system. I had tried that before but battery was weak. So I charged it up, and used just it and the landing lights come on with no issue. I do see a big amp hit when they first light but it settles in at 5-6A. I also attached the power supply with the battery and it worked, but I can see the power supply putting 10 amps into charging the battery so I don't want to leave that on for long. I'll look for some LED landing lights that fit Duct Work fixtures.

Thanks Much
 
I also attached the power supply with the battery and it worked, but I can see the power supply putting 10 amps into charging the battery so I don't want to leave that on for long.

That's just saying that your battery still isn't fully charged. If you leave it connected for a while, that 10 amp rate should go down to almost zero as the battery charges. Your battery doesn't know the difference between the 14.2 volts of your power supply or 14.2 volts from an alternator.
 
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