In the Serpent Viper 977 the battery is mounted on one side of the tank and the nice receiver box further away on the opposite side, so the wire to the receiver-box is a bit longer then usual.
We recommeded to use a battery cable of 20cm. For most brands its readily available, for some you may need to make an extension.
On the image you can also see the routing of the cable we recommend to use.
The completed assembly when installed.