I'm wanting to install a 12v outlet on my boat for phone charger, spotlight, etc. Can I simply run the red and black wire from the plug to the battery, and install an in line fuse near the battery? Also, would it be better to run the wires to the cranking battery or trolling motor battery?

Yes, you can run the wires back. However, If you have a master power switch, you would be better off running the wires into that circuit. Most accessories are run off of cranking batteries.

This is good advice. What kind of boat are you running? Also is your trolling motor setup 12 volt?

assuming you have a console with gauges and such, there should be a fuse panel underneath that is switched by your key or main power switch. Most boat makers leave a few open ports, if you have one you can add a new fuse and run a + to the terminal on it and a - to the ground bus and you are good to go.

If you don't have any open spots on that circuit, you can add one to run your outlet and any other accessories.

I added a separate circuit just to run electronics because my main power circuit would shut off the electronics anytime i cranked the big motor. Problem solved. depending on your needs and setup, this might be overkill

I have a Tracker pro 160. I don't think there is a fuse panel but I'll double check when I get home. My trolling motor is a 12v, I only have 2 batteries, one cranking and one trolling.

that model has a console, so i would be surprised if there wasn't a fuse panel up under there.

The only reason I say I dont think it has one, is that everything is currently run to my batteries. I had two graphs installed last year and he ran them both directly to the battery. The fuses for the bilge, livewell, and lights are the glass cylinder type and they're located right next to the switches.

be aware of the wire guage; you need it sized to handle the amperage drawn by what ever you plug into the outlet. also, don't forget a fuse or breaker in the circuit- placed in the positive conductor. this might save you a lot of trouble or money in the future.

in marine applications, I think it is a good idea to solder all connections.

Yep then there may not be a fuse bus.

You can certainly add another + back to the battery post. Quick & simple, but every time you disconnect or replace the battery you have to account for all the leads.

If you want to consolidate just add a fuse bus underneath and run your graphs and outlet off that. I ran 10ga to mine which carries more amps than i need today, but i won't have to re-do it if i ever want to add more stuff later. Also i ran it to a switch up front so i can kill the circuit when i put the boat up.

I would run it off my cranking battery because it will recharge as you drive and the trolling motor battery doesn't. Being only 12v you need to save all that juice that you might need during the day