Hey guys, Past two days I've been on a job and had sixteen 10-minute flights on my C8 - no symptoms of any serious problem and then... After one flight I went to change batteries and disconnect the parallel XT60's that connect the dual batteries to my machine and noticed immediately one of the connectors was very hot to the touch - so hot it had melted the solder at the joint (on the copter side) and almost separated the wire from the connector. The other one was not hot at all. I figured I was a victim of a solder joint gone bad, and I had some more shots to do later in the day, so I flew a few more flights with just one battery on the remaining "good" xt60 connector. Well after 5 more flights, that connector did the same thing. It got super hot and melted the solder at the joint. I monitor my motor temps and ESC's after flight with a lazer temp gauge. Most motors are consistent, in the 110-120F range, with one motor that sometimes creeps up to 160F. The ESC's are all about 95F after a flight. I had planned to change that one motor when I got home from this shoot, but still, I'm not sure that would cause the issue I'm experiencing. But maybe? Any ideas on what could be causing this, and more importantly, what would be the best plan of attack to troubleshoot? Other mitigating factors: My last shoot was at Burning Man - dustiest place you could ever think of flying. There's no avoiding it. I blew everything out with an air compressor after the shoot, and all the motors/bearings still feel super-smooth. Could residual dust deep in the motors cause this? This shoot today was a little hot and high - 3000ft and 92F. But Burning Man was higher (4000ft) and hotter and I had no issues there.
Bryan what batteries, what is the all up weight of your copter, motor, props, power distribution system, battery wire gauge and ESC's? Any photos of the damage? Suggestion that if one pair had a melt down it was pretty likely that the other side, being only a single battery and wiring pair would get hotter. If I fly mine when it's heavy that's why I use two batteries. Greatly reduces the temp on the pwoer wiring and the temp on the battery. Lot of questions but need more information to help you.
Hi Gary, My C8/camera ship is about 15lbs AUW. I have had about 200 flights on this setup with no hot wires. It hovers at 55-60% throttle. I am using Avroto 2814 motors, APC 14 x 4.7 SF props, Turnigy Plush 30A speed controllers, WKM flight control, Zippy 8000Mah batteries with 8 gauge wire. The wire that melted going into the copter is 12 gauge. I fly the 5dm2 with 24mm IS prime on a 3 axis gimbal. This photo is the first one that melted, taken before I switched over to just flying the single battery on the other one.
Bryan: Given the 200 flight history, it sounds more likely that the solder joint fatigued over time rather than being a dry joint at the outset. But that said, the solder cup on the red lead that separated looks like it pulled out cleanly -- which tends to undercut my "fatigued" theory and more suggests a dry joint that gradually oxidized, increasing resistance until that resistance started to generate enough heat to enter thermal "runaway" and melt the solder. I typically use EC-5's but I did find that when you are soldering tinned 10 or 12 ga. wire, if the solder in the cup is molten when you first plunge the tinned wire into it, it shock cools the solder in the cup and increased the number of times a dry joint resulted. So now, after I insert the tinned wire into the cup, I will deliberate keep the soldering iron on the cup until I can see that the solder has come back up to melting point and re-flowed. Hope this helps. Andy.
hey thanks guys, I resoldered new XT60's and I'm not getting any hot wires at the power distribution, so I guess that's fixed.