whats the best way to do this?

run an isolator or not? I was told by a stereo repair man its best not to run an isolator, just make a run of pos. and ground it, that way both batteries are constantly charging and avail. for current draw from the amps.

I'm not well versed in this area... help.

Stereo repair man is correct!

You can use an isolator when you want to play the stereo with the car off to prevent the stereo from draining the starting batt.

thanks,

it made sense to me, just wanted to check.

Usually you get a voltage drop through an isolator, that is why you don't use on amps if you don't have to. You can also run like a boat switch to cut power to second battery if you want to not kill the car if it is not running. My kicker will shut off and my car will still start. I would recommend you fuse every wire you add at the positive post of any battery you add wire to or install.