is there a possible way to repair this external battery?

its apacer B120 li-ion 6600mah @3.7v    (3x18650)

a friend of mine test one of those 3 leg diodes  (not the burned ones) he said it gives strange number cant find you a replacement :(
i dont know how to measure just solder
so if anyone can provide any help its welcome
non of the usb works

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-max-2 years ago

Most likely not worth it. You can attempt to see if you can figure out what parts burned out, If you can identify what type of components or the SOT323 packages, you might be able to find similar parts on other junk circuit board in your junk bin.


One upon a time, not too long ago, I had a small HUBSAN X4 quadcopter that had a damaged motor on it, and when I replaced it and soldered on the new one, I did not verify that the solder joint was good under magnification, just by a quick glance by eye. When I tried to fly it, the one motor did not spin, and the thing was browning out. (LEDs went dim on it) and I heard a POP and smelled the magic smoke! On inspection I found a really small strand of wire shorting across the solder pads for the replaced motor, and surely this was the cause of the failure, so I followed the trace back to one of 4 SOT23 devices on the board, and found that it was slightly discolored, bulged and maybe charred. Hard to tell. I have realised the 4 transistors next to each other were effectively the 4 motor speed controllers (ESCs) for the quad, most likely driven with PWM from a central microcontroller.

Then I had to figure out what type of transistor it most likely was. The part number on it pulled up conflicting datasheets online (some JFETs, some BJTs, some MOSFETs.) And judging by the fact that the 'gate' or 'base' was wired directly to the microcontroller, I figured the input has to be high impedance and easy to drive, so I took guessed it was a MOSFET, as most switching devices nowadays are. I took the soldering iron, scrapped of that dead FET, salvaged another MOSFET off of a 3A 3.7V LED driver board, (what I figure will be the closest equivalent part), tested it to verify it also is a FET with a simple LED circuit turned on and off with my finger on the gate, and sure enough, that worked, so soldered it on the unpopulated spot on the HUBSAN control board. Sure enough, it worked perfectly afterwards! (Well, there was one issue that arrised with the motor twitching on power up due to a really microscopic 0402 part that I came off because of my clumsy soldering iron and hands attempting to take off the FET.)


Soldering such small SMD parts without solder paste and a heat gun or a reflow oven is a royal pain in the ass, but it is doable even with a entry level temperature controlled soldering iron w/ small chisle tip. (velleman 3-in-1 lab thing.)

turbiny (author)  -max-2 years ago

i do have a hot air gun with regulated soldering iron and i`m getting some solder paste in couple of days.
thnx for your story i hope others will learn from your mistake

-max- turbiny2 years ago

I would recommend the same process to repairing this board if you cannot buy a new one.

But if you do not want the hassel, and uncertaindy of repair, then just buy one of the other cheepie boards on the market.

iceng -max-2 years ago

Amazing $3.42 for an entire Up-converter.

Engineered to a Chines knife's edge using the ring their bell curve =>> worst counterfeit components.

There is only a 1.001 design safety factor (I am being generous) as opposed to the minimum 1.5 USA factor.

No wonder any protuberance smokes such a board.

-max- iceng2 years ago

Meh, for $3, who cares. I don't. If it smokes, then I generally fix it, or toss it and get another one if the effort to fix it outweighs the time to get a new one. I had a power bank fail on me in a similar way, and did repair it, and it did work for some time afterwards. Although some reason the low voltage cutoff did not work properly and

iceng -max-2 years ago

Exactly ! My big picture is China is conditioning me and thousands of others in the throw away philosophy and thanks to eX President Clinton we also have to use lead free solder that hardens and cracks after a time making us vulnerable to becoming a throw away nation.

I want electronics that will not fail in the middle of a tri-copter flight and I personally will pay more or design and build my own ESC.

-max- iceng2 years ago

I have made a quadcopter, and have got some nice shots with it, but it is like a 70 year old person with cancel, diabetes, and a million other issues. Things just dont always work , and it keeps needing attention and fixing!

Just today when I went for a flight, the gimbal was going completly crazy, the battery voltage went below 1.6V/cell before I noticed, the buzzer did not work, (well it did but I ignored it after landing and testing) and the GPS and OSD for FPV half the time do not initiate, and the cloverleaf antenna somehow got crushed and the coaxial cable frayed. Most of these issues are software, and seem to go away on reboots, but never permanently. X-(

I did expect some issues due to bad connections, but that is not the case for a lot of the stuff. I think grounding is another issue that need attention too. Everything is daisy-chained together, and with signal wires floating around close to long ground wires, I think I have some issues there. I am too lazy to attend to them though.

-max- turbiny2 years ago

For my quadcopter, which would be $50 for another one, repairing the board was worth it, but risky. The actual story is much longer, with me initially attempting to solder a microphone to the unpopulated area of the board for audio, since it really has no audio other than the electrical noise. After taking it apart and doing mods to the camera recording board and the FC, I had nothing but problems arise. The quadcopter losing control and crashing, breaking the motor was one of them. Another, unrelated issue that was really hard to spot was that the camera would sometimes not record. Annoyingly, it worked fine every time I took it apart and tested it, but not on the field. Turned out it was too little solder on a bypass capacitor, I must have wicked off all the solder from it when I wicked away the solder to solder a too-big microphone. I never could get the microphone to fit no matter what I did, so I just gave up and fixed all the other issues I caused.

Currently, I am almost as good at fixing things as I am at breaking things. :) Though some days that is not true at all.

turbiny (author) 2 years ago

SRBC509 this marking is on the board it seems like its not apacer exclusive board
couldnt find any schematics

Q13 and Q16? are definately fried.
If you can read the markings on them you might be able to find a replacement but soldering SMD parts without the right tools is not for the faint of heart....

Depending on the functions of the failed parts and voltages/amps involved there is a good chance that other parts got damaged too.

In case you find replacement parts try it, otherwise a new board would be best.

turbiny (author)  Downunder35m2 years ago

Q16=X1HA (15 sideways writen)
Q13=AF1V (2G sideways writen)