ESC Meltdown

[TechGeezer]

I built an FT explorer using the standard comonents and C power pack, FrSky X8R receiver, Eagle Tree Vector comtroller using the SBUS connection between X8R and Vector. Also the RSSI connection between X8R and Vector. All seemed relatively normal in bench testing. Next I wanted to display Vector telemetry on the Taranis transmitter and followed instruction on the internet for connection between UART port on the Vector and Smartbus port on the X8R. Powered up the system, (Titan 4S lithium ion) and all seemed normal until I touched the throttle control...observed a couple of twitches of control surfaces and then noticed smoke coming from the motor and ESC. In trouble shooting I found that one leads from ESC to motor had melted the solder joint and came lose.

Next I replaced the ESC with a new BLHeli 30A unit but left the motor disconnected. Powered up the system again ... Another ESC meltdown and again one of the motor leads melted the solder joint on the ESC board. How do you smoke and ESC with no motor connected.

Speculated that somehow the telemetry connection from UART to Smartbus was the culprit. Removed the telemetry cable, replaced the ESC, reconfigured the Vector from factory defaults, etc.. Still had the RSSI connection between receiver and Vector. Testing seemed normal again, control surfaces responded as expected, motor responded to throttle as expected... But still 1 issue with RSSI values reported by the Vector not matching the Taranis, but thats a different discussion. I tried one last change, Rebound the X8R receiver to the transmitter in Mode 2 (no telemetry) instead of mode 5. Plugged in a 4S battery but only got 2 beeps instead of the expected 4. Tried again with same results, Swapped to a 3S battery, a couple of beeps then smoke from the ESC and motor, both overheated.

I searched the internet for similar problems, but no luck. Any theories why the ESC's are getting smoked? Any suggestions appreciated.

 

[RCdiy]

Post is the electric aircraft forum
http://forum.flitetest.com/forumdisplay.php?114-Electric-Aircraft
Maybe provide pictures showing the connections with easy to see polarity of the wires at each connection.

 

[cranialrectosis]

I too have torched ESCs and motors. The smell lingers for days.

I never found the culprit. I only ever ended up with guesses, but I did adopt new processes that have prevented many smokings since.

My home is at 6,300 ft along the Front Range of the Rocky Mountains in Colorado Springs. The air here is always dry, always dusty. We get lots of intense lightning in the summer months. It is common to get a zap getting in and out of my truck in the winter months and I absolutely have to use a static discharge wrist strap when assembling computers in my basement shop.

Still, even with the wrist strap, I continued to smoke ESCs in 2014 for no apparent reason. It was getting expensive and that smell...

My best guess is that I overheated or underheated a solder joint as root cause. Overheating causes shorts. Underheating causes cold solder joints.

Motor twitching is a sure sign of a poor solder joint. If a motor is twitching when you add throttle, back off immediately and re-solder the connections between the motor and the ESC. If you push it, you will smoke both. Be sure to remove any enamel from the motor leads. Yes, some manufacturers coat the motor leads with enamel that you have to burn or sand off the wires before your solder will stick. If you fail to remove the enamel and push a twitchy motor, that smell...

Overheating an ESC is very easy with the tiny little ESCs we use today. Be sure the pads are clean and tinned with your own solder. Don't mix your solder with solder that is already on the ESC. Move quickly, use a wrist strap, and don't overheat the ESC. After you complete the solder work, inspect the entire ESC for tiny little solder balls that get into the pins on the components and cause shorts, no motor needed.

I have to put on my cheaters to see the little solder balls these days and it makes me feel old as heck but it's better than having to explain to my long suffering wife why her house reeks of burnt KISS ESC.

With all the precautions I learned, I still smoked an occasional ESC, sometimes a motor and once even a flight controller (reversed polarity on an ESC to FC connection). Mistakes happen so some genius invented the smokestopper. Now, EVERY SINGLE TIME I touch one of my copters with a soldering iron, I smoketest before I attach a lipo directly to a project. It is a simple step and you can build a smoke stopper in a few minutes with inexpensive parts.

I have never lost a motor or reeked up the house, in this particular fashion anyway, since I began smoke testing.