Letting some smoke out!

If you not afraid to share little mistakes, here is the place.

Ill go first:

I am running around like crazy, and tried to replace my Sonoff basics with Sonoff POW’s this weekend, not thinking, nor remembering that you should never flash a Sonoff while connected to AC, I connected the VCC. Nice big sparks and a fairly nice bang was followed by darkness as the earth-leakage tripped, that was about the time I realised I messed up!!

USB Hub, ttl converter, sonoff POW and only one usb port on PC’s motherboard blown.

Please remember not to flash a sonoff this way…

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something easily forgotten.

A USB isolator is a good idea when the TTL converter itself is not isolated and it might have prevented this or at least protected your PC.
Here is an example of one, but there are many:

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Ouch, sorry to hear about the escaping magic smoke, but a good warning to all. I am about to flash a Bneta smart wifi plug with power meter to Tasmota, so will make extra sure on all connections.

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You can use a Victron VE-Direct cable. It’s a normal FTDi usb-serial converter with an isolation level. A bit of an expensive cable, but if you must flash in this manner, and you already have such a cable… :slight_smile:

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Sharing … ok, let me share WHY I don’t want to do things myself anymore.

I have, from top to bottom:

  1. Melted a connector box and burnt out the diodes on a solar panel. The diode was replaced and the panel still worked.
    Conclusion: Don’t install panels at 12pm on a Cpt summer day whilst sitting on the edge of a double story roof whilst thinking of sitting under an aircon with a beer, series-parallel connections will get confusing.
  2. Let the smoke out on a 12v inverter connected to a 24v battery. Took a few minutes before the white smoke came out. It was repaired to last a few months longer till it finally gave up.
    Conclusion: Don’t get any new ideas late at night No, just don’t.
  3. Burnt out a Phocos MPPT by installing it in a cupboard.
    Conclusion: Keep MPPT’s well ventilated.
  4. Numerous UPS’e saw the smoke let out of them when connecting pos to neg.
    Conclusion: Don’t be in a hurry, being overcautious, under pressure. Take your time! Relax.
  5. 100ah lead acid batteries shorted …
    Conclusion: Don’t be in a hurry, being overcautious, under pressure. Step back and relax!
  6. Burnt out 1 x BMS. When translating from Chinese to English, a LOT is lost in translation. Even drawing pictures helped naught.
    Conclusion: Speak to someone who can translate Chinese instructions to English, then write your own manual.
  7. When you have volt measuring wires and after all and sundry has been disconnected, you don’t think and pull the wires back out of the trunking … just don’t!
    Them wires become instant heating elements with the room filled with white smoke so thick you cannot see your hand in front of your face … and grabbing them with your hands to rip them off … a even worse idea that! Burnt human flesh stinks something aweful.
    Conclusion: Remember to disconnect both sides! Put Anderson Connectors on ALL little wires (fuses where you can) so that you can 1) remember to disconnect them and 2) can disconnect them quickly and easily with no smell emanating from your hands. Grab pliers, NOT scissors, if you forgot.

The above a very costly Doctoral Degree in “What The F$%* Not To Do.” :laughing:

And that is why I would rather ask “less qualified” people today to help me out. It saves ME a ton of money, to pay others to help make connections simpler.


When I started playing with inverters, my first jobbie was a Chinese 24V 3000W Changi.

Still learning and finding my feet at the time, my Changi got powered by 2 x 200Ah AGM’s which in turn got charged with 3 x 18V Solaris PV’s (Voc about 22V) connected in parallel through a PWM controller I got from a friend, worth about R600.00

The PWM is rated for 12/24V and able to deliver 20A

I figured that the panels being 2nd hand, and not tracking the sun, I would get nowhere near 20A.

I fried it within a week. I could smell the plastic burn from about 15 meters away outside in the garage.

It was only some time after that I became aware of concepts like “cloud edge”, especially with no load on the inverter…

At least this is where I think I went wrong.

Fast forward to about a month ago. Got busy installing a BVM 712.

Shut everything down and proceeded to cut the negative DC line to wire in the shunt.

Just as I finished stripping one side of the wire I let it go and it dropped straight onto the battery’s + terminal…

I picked up my side cutter in the road, as the garage door was open at the time. The terminal actually melted a little in that split second. That deafening klapgeluid is nothing to smirk at. Mamparra!!!


The first time I got a nice 20C LiPo RC battery a few years ago I wanted to change the plug.
Took the knife and started to strip both positive and negative wires at the same time. You know: to save time.
After the pop I now know how they make serrated blades from a straight edge :smiley:

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Thankfully the last time I made sparks with a battery, was when I was undoing the cable on the starter solenoid of a David Brown tractor. The spanner briefly touched the grounded body of the tractor and some sparks flew… my father explained that you always remove the ground cable from the battery first, before working on the other side.

Serrated scissors too. :laughing:

Or when you don’t focus and that little busbar on the lithium batts connecting them together, when disconnecting just the one side, and the batt turns too far when you shuffle them around … I HATE that spark with a deep deep passion. :wink:

And because my son knows that … he will make a similar sound right behind me when he walks past when I’m having a look at the batts … if ever I wanted to kill a child in cold blood … THAT was the day he faced his instant demise. :laughing:

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Hahahahaha this is funny!!!:rofl:

I feel your pain! :laughing::laughing::laughing:

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Hi All

I switched the polarity on my elCheapo SAMLEX inverter (DC inputs) and a very small amount of smoke was released (as per @TheTerribleTriplet 's instructions). It is a solid 2000W model and has served me well as a camping DIY inverter for the bakkie… don’t really want to toss it…

Does anyone know a good place to send to for repair?


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Sorry people, my mistake must get the prize for not paying attention!

I bought a new Nitecor battery charger for AAA batteries. It came with a EU 2 prong plug which I hate.So, time to replace the plug with a SA 3 prong plug…

I fitted the new plug and went to plug it into the wall and charger…I had cut off the fitting that went into the charger so I now had a cable with 2 plugs on it. A 2 pin EU plug and a SA 3 pronged plug!


Man i almost fell of my chair laughing now… I can just imagine the words that came out after that…

That is absolutely a epic one @Padraic !!!
Did similar with a battery cable … But that’s bleh compared to your 2 plugs. :joy::joy::joy::joy:

Inverters often have reverse polarity protection that consists of a fuse and a large reverse-biased diode (or a FET that is pushed into conduction if you reverse the polarity). This causes the fuse to blow if you reverse the connection, and also clamps the voltage to a low value (0.7V or so for a large silicon diode) protecting the rest of the circuitry. Fixing it is sometimes as easy as replacing the fuse. The smoke might be from the fuse too. Sometimes it might take the diode with it too.

I did engineering at varsity, and I was building a power supply. Of course, it was late at night the day before the thing was due (probably a Sunday). I was busy soldering like mad, but luckily had a couple of each component so I felt pretty good.

Connected it the first time – it went dead immediately. Checked the fuse – it blew.
Put in a new fuse, checked all connections, connected it. Went dead immediately. Checked the fuse – it blew.
Put in a new fuse, getting worried (had like one left at this point). Double and triple checked everything. Tested some tracks. Corrected some less ideal solder joints.

Took a deep breath and lifted the PCB up one more time to test everything. Then I noticed on my desk were some component lead cut-offs… so every time I put the PCB down to plug it in, it shorted some of the tracks below and blew the fuse when I plugged it in :stuck_out_tongue:

Cleared the desk and everything worked fine!


I think it’s taken a diode (or 2)… so not in my skillset to fix… hence the need for a “guru”. :sweat_smile: