Re: Dual batteries? Am I set up for it?
It looks like you may have the "spot" for a second battery, but not anywhere near the items needed for a true "dual" battery system...
For that, you need a switch (perko or other), the appropriate gauge wires to connect all the batteries to the switch, and to each other, and then wire it into the existing system... You also have to be careful about how you connect two batteries together... series = 24v/same amps, parallel = 12v/double amps.
If you just wanted to plop in a second "independent" battery and wire that up to your radio your probably fine doing it with what you got.
If you want to set up the true dual battery system, you'll need to get the stuff I mentioned above.
Hope that helps!
There are lots of posts on setting up and running dual batteries if you need more info, you can do a search on them.
