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Power supply for avionics testing?

N546RV

Well Known Member
Wondering what people have used/are using for testing out their panels. I finished all my ground terminations today and decided it was time to try powering everything up. After double-checking all the plugs, in particular making sure the only pins getting 12VDC were the ones that were supposed to, it was time to give it a try.

My test plan was to connect the power supply to the main bus fuse block, and power up the Skyview displays and other peripherals. The supply I bought a while back is supposed to be good for 12A, which should be plenty to run the avionics - by the book, I should be drawing around 6.5A.

Well, I got a flicker from a couple panels, and a brief splash screen on one HDX, then nothing, then a repeat of this. Seemed a whole lot like a periodic voltage drop to me. Measuring across the power supply terminals, sure enough, I could see a little dip from time to time (though hard to pick this up on a digital multimeter).

So I started weeding out things on the bus. Eventually I weeded it down to just the two HDX displays, which only ought to draw 4.8A. Still no joy, same behavior. I tried my other, cheaper 10A power supply - same thing.

Finally, I powered each HDX display on individually from the original (12A) power supply. In this way, I was at least able to get each screen to boot up, but even then after boot the screen would flicker sporadically like the output still wasn't steady.

It seems clear to me that the power supply I have isn't up to the task, though it ought to be based on the stated output. And yet I see elsewhere on the forums people saying that a 10-15A power supply ought to be just fine.

Did I just buy a clunker/Chinesium POS? I did, after all, come from Amazon.

I guess my next step is to see if maybe my neighbor has a better supply I can borrow - he's got a hangar full of every device imaginable.

On the one hand, I'm bummed I didn't have my weekend culminate with the whole panel lighting up, but on the other hand, this is nothing compared to my worst nightmare of letting out the magic smoke...
 
Thanks. I'm going to try adding a battery in parallel tomorrow to see if that can help smooth things out. Will probably end up getting another/better supply, though.
 
I successfully built, wired, tested and operated my G3X panel, including nav/coms both on the bench and in the plane using my deep-cycle trolling motor battery with a master switch.

When I asked Stein about a power supply he suggested that for safety only use one in conjunction with a battery. I decided to only use the battery and it worked fine.

I will continue to use it for the final wiring testing before I start beating up my PC680.
 
When I asked Stein about a power supply he suggested that for safety only use one in conjunction with a battery. I decided to only use the battery and it worked fine.

.

+1

Always a good idea to have a battery in loop if using anything but a quality regulated power supply. THe battery helps to absorb ripples and other undesired outputs from low end supplies or chargers. It will also step in and deal with transient high current demands, like startup.

Unsure if this is the OP's issue though.

Larry
 
I think my 12 volt bench power supply is a 60 Amp, so have never had to worry about overloading it for normal avionics testing. My 24 volt (for the little jet) is from the internet, and looks liek a computer power supply - it will only power a couple of circuits at a time.

Make sure that when you’re doing your calculations that you take the Master Contactor into account - those things pull about 5 amps all by themselves, so if you’re powering through that, you’re wasting more electrons than in your whole EFIS….

Paul
 
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Check out the one posted FS today

If you want a top of the line Power Supply check out the Red Box RBPS50 that my brother listed today in the classifieds.

I used this power supply many times when we shared a hangar and it's sweet. If no one else grabs it today, I might have to buy it myself.:)
 
You should not be seeing this if your 12amp power supply is working. I suggest you first look at how you jumper the power supply to your plane - look for a loose connector on whatever breaker you may have tapped into.

The simple check is to try another power supply first.

As you point out, your panel only loads should be 10amps or less (unless you are transmitting).

I have used this simple 30 amp regulated supply for years. Plenty of power to run the panel and charge the batteries (two PC-625s in parallel for standard ops). I never run avionics on a dirty battery charger. Even with a battery in parallel the battery will do little to filter out AC ripple and other such trash.

https://www.dxengineering.com/searc...cending&autoview=SKU&keyword=mfj power supply

Carl
 
You should not be seeing this if your 12amp power supply is working. I suggest you first look at how you jumper the power supply to your plane - look for a loose connector on whatever breaker you may have tapped into.

The simple check is to try another power supply first.

As you point out, your panel only loads should be 10amps or less (unless you are transmitting).

I have used this simple 30 amp regulated supply for years. Plenty of power to run the panel and charge the batteries (two PC-625s in parallel for standard ops). I never run avionics on a dirty battery charger. Even with a battery in parallel the battery will do little to filter out AC ripple and other such trash.

https://www.dxengineering.com/searc...cending&autoview=SKU&keyword=mfj power supply

Carl

I don't think I mentioned it previously, but I did try another power supply. That was a cheaper 10A that I bought some time ago. I had the same results with that supply, which did prompt me to consider other potential issues

The first power on attempt was connected as such:

PS -> main bus fuse block -> isolation diode -> e-bus fuse block, with fuses in place to send power to basically all of the avionics.

Eventually, I whittled that down to where I only had the fuses installed for the HDX display feeds (one on the main bus and one on the e-bus). With that setup, I'd still get the momentary splash screen from the main-bus fed HDX, and never a peep from the e-bus fed one. These symptoms were the same with either power supply.

When I was finally able to get a boot, I'd simplified the connections to:

PS -> fuse block feed to HDX

That is, I disconnected the HDX power feed from the fuse block, made a jumper wire with a male fast-on, and plugged that into the feed. So literally just the PS connected to a wire that fed nothing but the display. In that situation I got a full boot but still a flickering display, as seen here: https://www.youtube.com/watch?v=q6wWSZdIKj0

I got that same behavior when direct feeding either display, which tells me its unlikely to be a wiring fault unless 1) it's a fault somehow common to two independent feeds or 2) I messed the same thing up on both feeds. Possible, but seems unlikely to me.

On the other hand, both the power supplies I have are from Amazon, and I figure the chances of both being subpar quality are reasonable. So at the moment I lean more in that direction, though I think some more troubleshooting could easily refine things.

I wonder if it'd be worthwhile to fab up a stub HDX harness with just the power/ground leads for an even more isolated test? Pretty sure I've got the stuff lying around to make that happen.
 
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Phil,

I would suggest you get a high quality power supply designed for ham radio which will have good filtering and output 13.8 volts with higher current to handle inrush starting currents. I purchased a 50 amp unit that allows me to run the lights as well as all the avionics. I also use it for powering the panel for longer periods for software updates and to practice/learn the avionics. I've been very happy with this supply.

The one I purchased and am very happy with came from GigaParts (specializing in ham radio equipment): https://www.gigaparts.com/astron-ss-50m.html

While this isn't a cheap power supply, with all that I have invested in the avionics, I was not going to cheap out on the ground power. This one has most of the protection and filtering you could want.

Cheers,
 
Well, I may have impugned the honor of my power supply unjustly. This morning I pulled a motorcycle battery for further testing. It had been sitting for a while so I put it on the charger. As of a few minutes ago it had finished (verified by multimeter). Connected my ground and power to the one display - same behavior, occasional flickers with no full boot.

Guess I will be trying that stub test harness idea. Clearly something wacky is going on here, the question is what that something is...
 
A big danger, when using an external power supply or battery, is reversing polarity. Doing that can damage wiring and expensive avionics. A good way to protect against reversed polarity is to put a 2 or 3 amp fuse between the contactor coil and master switch, that is assuming that the contactor coil has an arc suppression diode across the coil. If battery polarity is reversed, then the diode will conduct heavy current around the contactor coil and blow the fuse, preventing the contactor from energizing.
 
Well, Carl wins the "I told you so" award for today. I'll spare the details of today's troubleshooting but it eventually became clear that the alligator-clip leads I was using were the issue. After swapping those out for faston connectors at the aircraft connection points and using bare wire on the power supply posts, things are up and running.

Well, mostly. GPS-175 isn't powering up for some reason, but all the Skyview components are alive and talking amongst themselves.
 
+1

Always a good idea to have a battery in loop if using anything but a quality regulated power supply. THe battery helps to absorb ripples and other undesired outputs from low end supplies or chargers. It will also step in and deal with transient high current demands, like startup.

Unsure if this is the OP's issue though.

Larry

These various 12v power supplies don't have any float mode circuitry. Do you have any concerns about overcharging the airplane's battery if hooked up this way, with the battery in the loop?
 
Just me

In my setup, I have an external power supply interface that is diode protected; the supply cant be hooked up backwards. But my bench supply is not big enough to put out the 9 amps when the panel is fully lit up.

So I have resorted to running the panel off my Odyssey battery. Last time, I had the 6Amp Odyssey charger hooked up to the battery, and the battery powering up the panel. ( The charger was providing power to the battery, and the battery providing power to the panel). This seemed to work fine at the time, but the next day, i plugged the charger into the battery just to charge and everything was wonked out. the battery showed low voltage, the charger showed a fault, and nothing would charge.
I turned everything off, ran the battery briefly without the charger, unplugged and re plugged in the charger to the wall, reattached the charger. it started to charge normally and after 4 hours seemed to have been full charged.

I am thinking I have a bad battery, but I will keep cycling the battery(never again hook the charger to the battery while panel being powered). I think the charger is not big enough to keep up with the panel draw, but that was on purpose to keep the charger voltage spikes from going into the panel. Maybe the charger freaks out when the battery voltage keeps dropping while it thinks it is being charged.

My solution is to spend the $30 and buy a better used power supply to power the panel for test.
 
My solution is to spend the $30 and buy a better used power supply to power the panel for test.

It's easy to have 30K in avionics these days, there is no way on this green earth I would ever risk powering up a panel like this with a cheap Chinese $30 power supply :eek::eek::

If you can't afford a good power supply/GPU you're better off IMO just getting a big car battery, play all you want, then charge it up when you are done.
 
I've been powering up my new panel for debugging with a 30A power supply with a 7A breaker in series. My HDX has the backup battery.

Simple VFR, with comm, intercom, six huVVer-AVI units, ADAHRS, OnSpeed and two autopilot servos (contacter not powered).

No problems, no breaker trip (but not TXing on the Comm). I think the key is that the HDX battery takes any power surges that would trip the power supply breaker.

When I want to do full integration testing, I will add the main battery to the mix.

V
 
So I have resorted to running the panel off my Odyssey battery. Last time, I had the 6Amp Odyssey charger hooked up to the battery, and the battery powering up the panel. ( The charger was providing power to the battery, and the battery providing power to the panel). This seemed to work fine at the time, but the next day, i plugged the charger into the battery just to charge and everything was wonked out. the battery showed low voltage, the charger showed a fault, and nothing would charge.
I turned everything off, ran the battery briefly without the charger, unplugged and re plugged in the charger to the wall, reattached the charger. it started to charge normally and after 4 hours seemed to have been full charged.

For avionics testing, I was originally leaving the cheap 2-4 amp float charger, that the airplane's previous owner had used, plugged into the parallel Odyssey batteries. This worked fine for him and for me for charging and for avionics testing but that little charger died and I replaced it with the 6A Odyssey charger. That charger has a desulfate mode, and I noted that when that charger was plugged in, there was a pulsing static noise from the headphones when the avionics were powered up. I figure that's not likely to be a good thing, so I'm now looking for a plain old 20-30 amp power supply to plug in in place of the pulsating Odyssey charger. I don't want to re-wire, hence my concern about overcharging the battery with a 12 volt power supply plugged for avionics testing through the batteries. Seems like pushing 30 amps into the battery for that period might represent an overcharge condition and boil the electrolyte.
 
For avionics testing, I was originally leaving the cheap 2-4 amp float charger, that the airplane's previous owner had used, plugged into the parallel Odyssey batteries. This worked fine for him and for me for charging and for avionics testing but that little charger died and I replaced it with the 6A Odyssey charger. That charger has a desulfate mode, and I noted that when that charger was plugged in, there was a pulsing static noise from the headphones when the avionics were powered up. I figure that's not likely to be a good thing, so I'm now looking for a plain old 20-30 amp power supply to plug in in place of the pulsating Odyssey charger. I don't want to re-wire, hence my concern about overcharging the battery with a 12 volt power supply plugged for avionics testing through the batteries. Seems like pushing 30 amps into the battery for that period might represent an overcharge condition and boil the electrolyte.

Try this -- https://www.amazon.com/gp/product/B000NPT4TK/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1

It's capable of 30A which is way more than a Dual G3X Touch, GTN 750Xi, GTR, GTX, Servos, et. will draw...

Its voltage is 13.8VDC which will charge Lead Acid, VRLA, LiFePo, etc.

Remember there's no danger of "overcharging" a battery based upon AMPs; Charging (and Overcharging) occurs when the battery voltage (potential) is lower than the supply (alternator, external source) voltage.
 

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Remember there's no danger of "overcharging" a battery based upon AMPs; Charging (and Overcharging) occurs when the battery voltage (potential) is lower than the supply (alternator, external source) voltage.
..................
 

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Solved

I just bought a 30v 10a supply from amazon. Problem solved.

With my diode isolated test power input, i can leave the master off when powering up the panel with this supply, so the battery will never seethe power supply voltage/current.
 
Working with the avionics could be a good opportunity to test your battery. If your battery can't power the avionics for 30 minutes, maybe it is time to get a new battery.

I suggest 30 minutes of reserve power fall very short of the mark. I design for no less than two hours of full IFR panel (note - that is with non panel loads isolated).

Carl
 
Early in the build, I put in an external Piper plug receptacle per the Nuckel's design. During the build I put an oldish Deep cycle out of my boat on the shop floor and used it to test all kinds of circuits, avionics, lights etc.
I didn't even install a ship's battery until first engine start about a year after first test via the external power.
Soon after my test phase with the airplane, but still new to the airplane, I did my first overnight. Returning to the airplane, I discovered that one of the master switch karma gnomes had turned on my master and left it on and drained the battery.
Fortunately, I had my Piper plug cables with me and a friendly looky-Lou on the ramp and was able to do a proper field test of the system.
I have since changed my personal SOP to where I alway leave the Nav light switch on so as I glance back at the airplane while leaving it, I can easily tell if the master switch is still on.
Needless to say, I'm a big fan of external power receptacles both for building and operating.
 
Try this -- https://www.amazon.com/gp/product/B000NPT4TK/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1

It's capable of 30A which is way more than a Dual G3X Touch, GTN 750Xi, GTR, GTX, Servos, et. will draw...

Its voltage is 13.8VDC which will charge Lead Acid, VRLA, LiFePo, etc.

Thanks, that's what I did. I just need something simple. I have a harness and plug under the dipstick door for the Odyssey charger to keep the 650's topped up. I'll just make up a harness with the same molex connector and plug this thing into it when working the avionics on the ground. I'm swapping my 430W for an IFD440 soon and I'm sure it will get a workout.
 

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Doit right.

It's easy to have 30K in avionics these days, there is no way on this green earth I would ever risk powering up a panel like this with a cheap Chinese $30 power supply :eek::eek::

If you can't afford a good power supply/GPU you're better off IMO just getting a big car battery, play all you want, then charge it up when you are done.

Absolutely!! Get a good unit. I recommend 35-or 45 amp version of this MFJ unit. They have adjustable voltage so you can use it to test low voltage on the bus and up to charging volts. I have a 30 amp and have blown the fuse when doing a full airframe test at full loads. It is dead quiet on the radios and not harmful to the battery either. You could use it at lowest volts to add a fixed charge for LiFePO battery too. Good for build, maintenance, and troubleshooting.

I don't place my trust in unknown stuff on Amazon. YMMV

Try this:
https://mfjenterprises.com/collections/power-supply

Also recommend Anderson Power connectors. Wired direct to the battery it can also be used with a LiPO emergency start battery or jumped, or for your maintenance processes.
 
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You should not be seeing this if your 12amp power supply is working. I suggest you first look at how you jumper the power supply to your plane - look for a loose connector on whatever breaker you may have tapped into.

The simple check is to try another power supply first.

As you point out, your panel only loads should be 10amps or less (unless you are transmitting).

I have used this simple 30 amp regulated supply for years. Plenty of power to run the panel and charge the batteries (two PC-625s in parallel for standard ops). I never run avionics on a dirty battery charger. Even with a battery in parallel the battery will do little to filter out AC ripple and other such trash.

https://www.dxengineering.com/searc...cending&autoview=SKU&keyword=mfj power supply

Carl

@ Carl. Probably going with this device. As you have experience with such, can it handle in-rush currents or should I put a battery in line when testing motors?
 
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