I didn't notice the Tru isolator. What @CID said.
Pretty much everything, especially high current stuff, that you may want to use with key-power off, should be powered by the Aux battery. If you don't do that, then the engine should be running (a sub-optimal alternative IMO). However, keep in mind that the alternator, at engine idle, is not able to generate all that much power, to do that the engine has to be up a few thousand RPM.
Bottom line, winch should go on the Aux, light bars maybe (my 52" draws over 16 amps) can go to either, but if you want to run the light bar for very long with engine off or at idle, it maybe should be powered by the aux.
There is a disadvantage to running the Aux battery ground to the main battery negative post. That means that ALL current from and to both batteries is running through that one wire. On the up side, that wire is short and any resistance is probably low, as long as ground connections are good. Good old redundancy, and avoiding potential for single point failure. would dictate the Aux is better off having it's own separate ground to the frame.
Pretty much everything, especially high current stuff, that you may want to use with key-power off, should be powered by the Aux battery. If you don't do that, then the engine should be running (a sub-optimal alternative IMO). However, keep in mind that the alternator, at engine idle, is not able to generate all that much power, to do that the engine has to be up a few thousand RPM.
Bottom line, winch should go on the Aux, light bars maybe (my 52" draws over 16 amps) can go to either, but if you want to run the light bar for very long with engine off or at idle, it maybe should be powered by the aux.
There is a disadvantage to running the Aux battery ground to the main battery negative post. That means that ALL current from and to both batteries is running through that one wire. On the up side, that wire is short and any resistance is probably low, as long as ground connections are good. Good old redundancy, and avoiding potential for single point failure. would dictate the Aux is better off having it's own separate ground to the frame.