What is the gound cable layout at the battery and the 3 post bar next to the battery box?

 

there are a bunch of small ground wires and I have one big one to winch(add-on) and one big one to bolt on alternator mount. Also, should be a ground on back on engine to firewall driver side. And of course one going to battery (-)

 

I have the negative post cable to the engine but there is a smaller cable that is on the 3 post bracket behind the battery that I'm not sure where it goes