HELP Please

[Maddy]

Im running a Durango 410
speed passion LPF speedo
speed passion 6.5 V3
87 spur
23 pinion
zero timming
forward only
DRRS start mode 9
brake mode 1
Ive always had a problem with the battery wires getting warm more the negative terminal side.
Today while doing a practise session i melted 2 sets of batterys,1 set of orion 5500 90c and 1 set of nano-tech 5100 65c.
the orions almost doubled in size just saving from exploding and the nano-tech melted the negative terminal out of the battery.
all wires have been checked and nothing has shorted out,all wires have been heat shrinked at the soldered ends so nothing is exposed and cant short out anywhere.
Anyone got any ideas before i bin the electrics and start fresh

Cheers