How to wire head unit into isolated marine battery system

[Chexi]

Any ideas on how to power the head unit via an isolated deep cycle battery (as opposed to using the harness and cranking battery)? Is this as simple as snipping the constant power line and butting in a line to the deep cycle power system? What about the key-on and the pencil accessories switch? Do they become obsolete in this setup? Finally, anyone have an idea on the gauge of wire that should be used to run the power to the head unit? Thanks.

[Mikeski]

RE: How to wire head unit into isolated marine battery syste

Power and ground (yellow and black) to the isolated battery via #16 or larger gauge wire. Red from desired switch to control the deck turn on. Typically it just trips a relay in the deck so you can cheat it off the stock harness or you can do it correctly and run another yellow wire from the iso battery to the "pencil" switch line and run the red from the other side of the switch to the deck, but you lose your key on-off (something I prefer).

[Chexi]

RE: How to wire head unit into isolated marine battery syste

Thanks Mikeski.