De soldering...HELP!

[ralphee]

Hey guys

OK need some advice from you brushless guys, as this was my first time today.
First off, here's what im running.

TRF501x
EZ run 5.5t brushless motor and speedo.
Kit spur, 17t pinion
Intellect 5200mah LIPO's
Speedo set to a punch factor of 6, with the highest being nine.

Today was my first time out, and after about 4 mins, the Neg wire to the LIPO's came desoldered......right off the Corally connector.

Normally id think i was overgeared, but it doesnt seem so, and the speedo and motor seemed not to warm at all, though it was hot today, i did make the mistake of not opening up the hot weather vents on the shell (though i have done now)...could that be a cause? Or maybe i just had a bad solder join to the Corally maybe?

Any advice really welcome, as im a bit stumped, going to re solder now, but dont really want to go out again, till i can get a rough idea of what i may have done wrong.

Thanks in advance.......lee