Electrical Mystery - some guidance needed for troubleshooting

[gomotomoto]

Yesterday, I toasted a brand new 4S 5000 mah 35-70 while setting up the naza (not flying). Something sucked out voltage FAST. Not sure how to troubleshoot so looking for some advice. I'll layout as much of the situation as possible, maybe someone can help me track down the issue:

Putting together a dji 550 with the following specs:

1. DJI Flamewheel 550
2. Aerial Media Pros Heavy Lift Kit
3. Naza V2 w GPS
4. Zenmuse h3-2d
5. iosd mini
6. TS832 5.8 32CH VTX
7. LED strips (2 red, 2 green, 2 blue) for orientation
8. FRSKY X8R rx
9. home made retractable landing gear

As mentioned above, I had my Lipo at storage charge around 3.75/cell & used it to set up the 550 with the naza assistant on the PC. I did the near identical thing with my 450 setup (stock, no accessories other than a few LEDs) and I was able to spend well over an hour powered up on the Lipo without going below 3.7/cell, so I don't think setting up the naza with the craft idle draws much current. So, I'm pretty sure I have an issue somewhere here's how I have everything set up:

• the craft powers up and everything looks operational, I figure if there was a short somewhere, it would have destroyed something but all seems ok, except there's a massive current draw somewhere.

• Naza power is simply soldered into the power distribution board.
• Zenmuse is also soldered to the + - on the power distribution board. iosd mini cable is tied into the zenmuse 3.5 jack line, wiring looks correct per the manual. This is a wiring harness that I had to make, not plug and play
• The TS832 say it can handle the juice from a 4S, so i've soldered the power wires direct to the power distribution board. I'm suspect of this because the VTX was noticeably warm. Is it possible, powering this up direct to the 4s is causing the issue, maybe it needs a voltage regulator? Still seems weird.
• I have alot of LED's connected, but I don't think they draw too hard, do they?
• landing gear is operated by two powerful little servos but didn't retract them much at all.

I'll have to get a new battery now, but don't want to trouble shoot with a 4s, so will get a smaller (cheaper) lipo to do my troubleshooting & naza setup with. Any suggestions for a lesser battery to set up with? Maybe I should get a second battery to power just the VTX?

Any help appreciated. I'm kinda stuck at the moment.

 

[araines2750]

Trace and double check all + & - connections. Do a very though job as it sounds like something is wired reverse polarity.
Don't just do a quick lookover..... trace each red wire to + and each black wire to -.
Really look at the connections at the PCB, depending on the board, these are easy to reverse.
Just my thoughts.
Andrew

 

[Benjamin Kenobi]

Sounds like a short somewhere as you suspect. It is normal for a VTx to get warm when powered up after a minute or two, mine does.

 

[buckers]

If possible after inspections, try to get an ammeter into the circuit and then remove things, one at a time until you find the part responsible for the high current draw.

 

[gomotomoto]

If possible after inspections, try to get an ammeter into the circuit and then remove things, one at a time until you find the part responsible for the high current draw.

Muliti meter ok? If so I guess just watch the current draw? If so I think I have what I need to start troubleshooting.

Is it possible that the little zenmuse 3.5mm connector and the iosd wiring is pulling that crazy draw? Not sure but I just thought that harness is connecting the video signal with a ground.


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[kloner]

you turn it to amps, make the ground circuit solid and stick your prongs into both hot leads on batt/multi to complete the circuit, one in each hole..... it will measure the draw to what your multimeter can handle....

be careful not to short anything out, might be wise to make an adapter to go inline with connectors that match it all, soldered, etc.....

 

[gomotomoto]

you turn it to amps, make the ground circuit solid and stick your prongs into both hot leads on batt/multi to complete the circuit, one in each hole..... it will measure the draw to what your multimeter can handle....

be careful not to short anything out, might be wise to make an adapter to go inline with connectors that match it all, soldered, etc.....

I'm electrically challenged, but getting better. Might have to talk to me like I'm 7 years old. when you say both hot leads, on batt/multi, I'm not exactly sure what to do, sorry hope I'm not frustrating you & I know your being super helpful.

I'm definitely stroking out on this one. I think I might just de-solder EVERYTHING and start over from scratch if I can't get the logic on what to do. Just don't want to short out anything or damage the components.

Just ordered up 3 new batteries. One 3s in case I have to sacrifice it while figuring this stuff out and the other two 5000mah batts to fly with (hopefully soon)

Appreciate all the help Kloner.

 

[Motopreserve]

Is it possible that the little zenmuse 3.5mm connector and the iosd wiring is pulling that crazy draw? Not sure but I just thought that harness is connecting the video signal with a ground.

sounds like checking all the wiring and solder points is the best bet - but FYI: in doing research about the Naza/Zenmuse/OSD for the Phantom2, DJI mentions that using the gimbal and OSD can take it from 25 to 15 minutes flight time. That's obviously a decent draw. Might be worth removing them to see if your new batteries are draining in the same way without them connected. With a basic meter you could stop it well before it reaches a damaging state.

 

[gomotomoto]

sounds like checking all the wiring and solder points is the best bet - but FYI: in doing research about the Naza/Zenmuse/OSD for the Phantom2, DJI mentions that using the gimbal and OSD can take it from 25 to 15 minutes flight time. That's obviously a decent draw. Might be worth removing them to see if your new batteries are draining in the same way without them connected. With a basic meter you could stop it well before it reaches a damaging state.

Interesting. Weird though...How could that little Zenmuse and IOSD draw much of anything, it's tiny... Perhaps its just the load of everything I've listed above. I guess altogether it's alot of pull.

I'm going to take the top plate off tonight and route every single wire and write it down so I don't get lost/loose track of what's been ruled out.

The 450 has none of those bells and whistles, so it kinda makes sense i guess. Either way, I'll be a monkey's uncle if I find something crossed, I was extremely careful soldering all those wires up.

I'll post back up with my findings. Sleep is over-rated anyway.

 

[Motopreserve]

I would imagine you won't be testing anything with a battery in storage/depleted state anymore either

i do it all the time too...

 

[gomotomoto]

I would imagine you won't be testing anything with a battery in storage/depleted state anymore either

i do it all the time too...

Ya, at $65 a pop -- I won't!


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[gomotomoto]

sounds like checking all the wiring and solder points is the best bet - but FYI: in doing research about the Naza/Zenmuse/OSD for the Phantom2, DJI mentions that using the gimbal and OSD can take it from 25 to 15 minutes flight time. That's obviously a decent draw. Might be worth removing them to see if your new batteries are draining in the same way without them connected. With a basic meter you could stop it well before it reaches a damaging state.

So, all my wiring looks correct, there wasn't any + or - connections reversed. I'm wondering if it's just the draw of the craft in it's current state. I have a feeling I just spazzed this and hung out with the craft on the bench, plugged in for too long at storage charge.

I'll know soon, a few more batteries on their way from hobbyking....

 

[kraftybrett]

You need to put a test inline with the battery and esc. Just connect the - batt lead to the - esc lead as normal set you meter to amps and conne the + meter lead to the + batt and the - meter lead to the + esc, fire everything up and check the current draw. If its high start disconnecting things like leds, gimbal etc to see if there is any significant amps drawn. Should be nomore than 1-2amps with the motor still and servos still. Let me know what current is being drawn. I suspect this problem is do to the battery voltage running to low and a cell/cells being damaged cheers Brett

 

[jes1111]

Most multimeters will top out at 10 amps - they usually have an internal fuse to protect them from going past that. So I wouldn't try measuring the pull - if it was enough to kill your battery, it will just pop the fuse.

I think you have to tackle this the hard way - pull the whole thing apart and test each component on its own

 

[Motopreserve]

It's been a while, but you did place a depleted battery on the bench and use it for an unknown period of time, correct? How about before you go tearing into things with hoists and pulleys, and pulling out the oscilloscope, you plug a CHARGED battery in there and keep a low voltage reader on it to see what comes of it? . Just unplug it if it starts to dip?

 

[gomotomoto]

It's been a while, but you did place a depleted battery on the bench and use it for an unknown period of time, correct? How about before you go tearing into things with hoists and pulleys, and pulling out the oscilloscope, you plug a CHARGED battery in there and keep a low voltage reader on it to see what comes of it? . Just unplug it if it starts to dip?

Yup. I did that.


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