TOPIC: Proper wire size for extending battery cables?

I have a 1961 14 ft Crestliner Mustang runabout that weighs 320 lbs)...its always been heavy at the rear with an outboard, two tanks of gas, and a battery. The boat never really wants to plane out (especially with anyone in the back seat; It has a bench seat in the front and one in the rear). I've been thinking about putting maybe one gas tank up under the front deck where dry storage is intended...but it'd be a pain in the rear to get in and out especially with it being full. There isn't enough room to fill it up where it'd set unless I drill a hole in the top of the deck and installed a gas cap. I don't really want to do all that so I've decided to just put my battery in the front BUT I will have to extend my battery cables 10 feet; I'm talking about the cables that crank the outboard. Is this ok? Because I know the longer the cable, the less fire there is. Will this burn anything up? What size of wire do I need to add on 10 ft to the cables? Electrical expert advice needed here. Thanks in advance.

I did the same thing. A lot of people told me it wouldn't work, but I haven't hadi an issue. I used 4 gauge wire and just so I didn't have to crimp battery cables together I used a terminal underneath the My thinking was that people relocate the battery to their trunk in cars all the time so there is no reason why it shouldn't work as well in a boat.

The larger the battery cable size the less current drop you will have. I've used 4 gauge as well to relocate the battery forward, but I believe that's about the smallest size you should use. 0 gauge would be better, but also heavier and more $. As long as you keep your outboard tuned properly so you're not cranking on it more than usual, you should be fine.

Terminal connections are something that make a big difference here as well. Crimped and/or soldered are preferred, with heat shrink or "liquid electrical tape" to seal the connection. Quality marine grade materials may cost a few pennies more initially, but pay off in the long run with trouble free service. If you don't have a source locally, I'll gladly share mine with you. Made in the USA, free shipping, and excellent customer service.

www.genuinedealz.com/

Note: I'm not affiliated with that site, just like to pass along a good bargain when I can!

cool site. There is even a cool voltage drop calculator if you wanted to get really nerdy about your cable run.
Thanks for sharing.

just got this from ebay for one of my projects . I'm sure it will work perfect for you.
you will also want these.

I am an electrician for an ambulance mfg. We use 2ga wire about 12ft to run our electrical panels. That includes all lights, sirens, radios, ect, ect. If we relocate the batteries we use 2/0 cable, but remember that is to start big modern engines and electronics that can't have any voltage drop. We use the same cable that Woodglass put up. If we use a 2ga positive we use a 4ga ground and so on. You would be surprised at how small a wire you can get away with. Crimp and seal with shrink tubing until you see a bead of resin come out, corrosion is your worst enemy and if you can see it it is too late. Happy boating

When I rebuilt my Herters a few years back the transom was so low I was worried about backsplash with the weight of the motor, fuel tank and battery so I moved both the fuel and battery to the bow. Went to the local farm store and bought about 35' of welding cable. The store(s) would also carry the terminal ends and heavy water proof shrink wrap. Came out with an almost perfect balance.