[wingtipper]

was at pemac today watching a sukhoi F35 twin 70 EDF thrust vectoring unit ripping through the sky when all of a sudden it went deadstick . it flew on a downward straight path for about 200mteres before it hit the ground . inspecting the wreckage with the owner we found the 6s 5000 mah battery 4mm bullet had de soldered and come off in flight .
the owner says that it was pulling around 130 amps on 6s the esc had its own bec .
and this is the 2nd time it's happened to him . no shit !
anything over 70 amps and i think a seperate bec would be a very good idea . perhaps 6mm bullet plugs and 10 aw wire too .
i use deans t connectors , so i normally cut the bullets off and solder deans t connectors on . which brings me to the next point , if your using batteries as they come ' i'd be putting a little extra solder of my own on the plugs . a lot of batteries have minimal solder applied to the plugs at factory .

just wanted to point out that i seen it with my own eyes . the solder melted away .

[samste]

Let me guess Ian's rc ?

Edited with more detail

It can happen but I think it's normally several things -

1. The solder that was used was the incorrect solder mix (too soft) as I use xt connectors and pull the same amps on my Edf Stryker but the solder I use needs a lot more heat to melt and i make sure they are well soldered.

Normally solder mixes for rc should not be an issue as there really should not be that much heat at connection unless there are other issues.

Normal Solder that is readily available and really should be Fine is 60/40 solder (60%Tin 40%Lead)
I have always been a firm believer of using 63/37 flows easier and when frezzes quickly its joint is shiny solid and good.
remember lead free solder has a higher melting temp than lead based.
lead based can range from 90 - 180 degrees while lead free is around 120 - upwards

2. A Common cause is the soldered connections are not fully soldered causing a hot joint to Happen which is more likely.
You need to fully soak wire in solder then connector with solder and join/melt the two Together

3. Loose connection with connectors can also cause this, common issue. make sure you have tight connections.

[gbanger]

I agree with Steve, generating enough heat to melt a solder joint can only come from a poor quality joint in the first place. I would suggest it was a crap joint to start with, a poor tradesman always blames his tools.

[Claudius]

remember lead free solder has a higher melting temp than lead based.

This is an important point to remember, particularly when wiring up ESCs etc using lead-based solder.

Whenever you get an ESC now, there's a good chance the motor/battery wires were pre-tinned at the factory with lead-free solder.

If you're using your lead-based solder you have to snip those ends off, or redo the pre-tinning yourself, or ensure your joint temperature gets high enough to melt the factory pre-tinned ends.

Otherwise, if you were to do the typical "drop a pool of lead-based solder in your battery connector and jam the ESC cable in", there's a good chance the (higher melting point) lead-free pre-tinned end didn't get hot enough to melt and form a proper joint... and you'll never know by looking, because the joint itself could look perfect on the outside.

[wingtipper]

yeah those points are all relevant .
this was a factory battery with bullets connected at factory . it failed on the battery bullet , not the esc bullet , which was soldered by the owner . . you could clearly see where it melted and the battery wire did not looked tinned , it was a typical hot joint . this was not a cheap battery either it was a high c rated 6s 5000mah .i have not had this issue cause i use deans t connectors that i fit myself , by default i have been snipping the bullets off and soldering my own fittings , however one could easily just use factory plugs on batteries , but look at them 1st in high discharge situations . i think this is a must now cause just looking at factory solders you'll know what i mean . i felt for the guy cause he was using FRSKY stuff too trying to get reliability . however . what he missed was having an external BEC and battery pack .
then he wouldve probably landed safely .

[Steven]

But yes... running that kind of current, an opti-esc would be more ... suitable.

[wingtipper]

rather than start a new thread i thought i'd add here . MAINTENANCE OF PLUGS !!!! doing some prop and current testing on my models using the watt meter i noticed some power cutouts and esc's rebooting . after a little fiddling i found that the t connectors ( deans plugs) i had soldered onto the wattmeter were the cause of bad connectivity . moving the plugs once connected together proved the point . Upon connecting these plugs there was no looseness and one would assume all was good with a good mated connection , changing the plug ultimately proved it as i could not break the connection with a new plug fitted .
JUST a reminder to constantly check plug connectivity , by wiggling and prodding pulling plugs, wires when connected on a regular basis as , failure to do so WILL RESULT IN DEADSTICK . ESPECIALLY take consideration ON ANYTHING PULLING OVER 20 AMPS AT A GUESS .
THIS IS GENERAL MAINTENANCE AND SHOULD NEVER BE OVERLOOKED .
CHEERS .
ALSO ALWAYS REMOVE COWELS AND CHECK SCREWS ON MOTORS , ( CASINGS/ MAGNETS? MOUNTS ETC as they do vibrate loose .

[secant0give]

Very good point Wingtipper !!
Any plugs that are on old lipo packs should not be de-soldered and re-used !!
and any male plugs on ESCs that draw high current should be changed from time to time as well.

One thing I found that almost caused me some greif, was that a fine string of Hot melt glue got on the pins of one of my plugs and caused intermitant contact. Those plugs got ditched ASAP !!

Also check what your reciever/radio gear failsafe settings are should something bad happen.