Tips (and rules) for lipos:

Fuse: The fuse must be equal or less than the max discharge of the pack. My fuse in Satanix is the maximum continuous current of my speedos. If your speedo is drawing its max current then there is something wrong. Better to blow the fuse than the lipo or speedo.

Metal box: As long as your robots base is 2mm non flammable metal you won't need a box. Padding when securing it down is essential, and make sure it can't slide anywhere.

Connectors: Deans or EC5's. Rules say they should be able to handle the amps, and with most lipo's only those would do. Plus, you can't accidently reverse the connection. The connections must be heatshrinked.

EDIT: Damn you PJ!