I think we are pushing the limit of wire length between the batteries and ESCs. Remember that long wires cause voltage spikes because of induction and that’s the reason why ESCs have capacitors in them. But those capacitors aren’t enough to support extra long wires. I’ve tried to keep my wires as short as possible including the leads of the batteries (this also keeps them out of the props). After I added added wire to connect two more batteries (total of 6) I had an ESC go bad on my first flight with that setup. I think the extra wire pushed it over the edge in combination of one year worth of previous wear from voltage spikes.
I replaced the bad ESC and added two more capacitors in parallel as close as possible to each ESC. The capacitors are identical to the ones inside the ESC. I covered the solder connection with liquid electrical tape and then used some 3D printed parts to secure them.
Here are the files:
Capacitor Holders - Top.stl (212.6 KB)
Capacitor Holders - Bottom.stl (190.3 KB)
Here is a link to the capacitors:
http://d.digikey.com/WS09IpX0N0g0K7k00RHoa01