So my F550 fell form the sky

[Asesapie]

View attachment 18989So I was filming the fireworks show here in a safe area where I didn't have a chance to damage anything in the event my 550 crashed. We'll I was flying about 2-3 minutes in and my 550 fell from the sky like a rock. I ran over to see the damage and the positive lead on the main EC5 plug came disconnected. The solder from inside the plug looks like it exploded. The pack, esc's and wires are all very very cool nothing too hot and this system has been tested several times before tonight.

Why would the solder have come disconnected? Bad solder joint or over amperage/heat? Please help, much appreciated.

 

[Motopreserve]

A bad solder joint could be from either of those issues (poor job to begin with or weakened by flex/heat). I always change the plugs on my batteries - so I know the tinning and solder job is my own.

 

[Old Man]

Looks like a poor solder joint but it could have been a combination of cold solder joint, vibration, and numerous times having the wire bent at the end of the connector. Soldering is a very bad way to set up electrical systems in aircraft but that's what we have to work with at the moment. An idea has one using a short piece of large heat shrink that covers part of the connector end to add rigidity to a soldered wire and prevent excessive bending of the wire at the connector solder joint.

 

[gtranquilla]

View attachment 18994If the soldering was done well it should have been more reliable unless you are carrying a very heavy payload such that current draw became excessive.
Was the original soldering joint nicely rounded and glossy (good) or gray and rough (not good)?

 

[tombrown1]

I'm very close to switching to Anderson PowerPoles. It's a mechanically crimped connection and allegedly very reliable.

 

[Asesapie]

I was carrying my normal payload just gimbal and camera. There really isn't any reason this joint should have come apart like it did. Every part on the 550 was cool and not hot like it should have been if it over amped the plug and caused it to pop like that. The solder appeared to be good but I'm having second thoughts on that now.

I flew lee this machine a good 6 times before last night and test flew it for 5-10 minutes before the flight last night with no issues. Where the plug was it had no way to flex and move.

 

[Old Man]

FYI, as we move forward we'll have to face regulations that place full scale methods as the means for setting up systems. Solder joints are not allowed.

OTH, the EC-5, when soldered correctly, is a quite robust solder joint and capable of sustaining high current if the wire is sized correctly. It sounds like it was a bad joint to begin with. If using high strand count wire it can be a bit difficult to correctly tin the wire prior to inserting into an EC-5 socket. If you choose to go with Anderson's make sure you size them for the anticipated amperage. Anderson has quite a size selection to choose from. They are indeed extremely reliable.

 

[Asesapie]

It is wired with 12 gauge deans ultra wire. To me it has to be a bad joint and unfortunately a bad joint I didn't solder together. I'll have to see what can be done.

Thanks everyone

 

[mangoats]

There are actually 2 possibilities that could cause this to happen. We see this fairly frequent on the high power RC helicopter side of the hobby. Mostly from people who don't size their plugs.

The solder joint is the first possibility as everyone else has pointed out. The second, is when the lead is plugged together, that the mail pin is loose inside the female cup. All it takes is it being a little loose, this causes a short that will lead to a large amount of heat. Once the heat builds up enough, the solder joint will fail.

Stock PR6 plugs have a habit of this type of failure, you need to check and size your connectors on a regular basis. I personally have had one de-solder in flight from a PRC6 that was not sized correctly.

When you plug a connector together you get a false sense of how tight they are. Once side could be super tight, while the other side is loose. On a PRC6 you need to turn the plug sideways and plug one side in at a time. This lets you know how tight each side of the plug is. Once you know they're tight, you plug it in as normal. If one side is loose, you simple size the plug by opening up the male side a small amount.

EC5 connectors have a square and round housing, this makes it hard to actually test if one of the connectors is loose while connected. You really cannot just plug one half in at a time to see how tight each side is.

Hope this helps a little....................

Thanks,
Chris