[suicideneil]

Locking battery connectors for those kinda currents dont really exist, atleast not small enough for r/c use.

Deans plugs and traxxas connectors are normally very tight, very rare that they would come apart.

Same is true of bullet plugs; take a small allen key and insert it into hole down the centre of the male connector, then wiggle it around to push out the pins slightly. It should be a much tigher fit into the female connector afterwards.

Only other thing I could suggest is to look at your wiring and shorten it where possible, as less wire = less weight & strain on the plugs...