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ContinuousWave: Small Boat Electrical
Extending Battery Cables
|Author||Topic: Extending Battery Cables|
posted 10-26-2014 01:30 PM ET (US)
I plan on mounting the starting battery in the center console of my 15-footer. The original battery cables are too short. Should I install new cables from the outboard to the new battery location? They will run through a tunnel, under the deck, not a dry location. I could save [money] if I spliced them. What is the best method for splices?
posted 10-26-2014 02:50 PM ET (US)
If you want to keep your OEM cables, the use of power posts is a good alternative, better in my opinion than splicing. Use larger gauge cables (2-AWG) from you battery to the posts somewhere in the stern areas, on which your OEM cables (most likely 4-AWG) will be connected.
posted 10-26-2014 06:25 PM ET (US)
That's exactly what I've done on my 1991 Otrage 17, securing the posts on a 6-inch x 6-inch piece of KING Starboard inside one of the stern quarter seats storage, where the battery previously was: http://www.myfishingpictures.com/data/500/medium/power_posts.jpg
posted 10-26-2014 10:04 PM ET (US)
Avoid splicing or making any sort of break in the engine cranking battery cables.
posted 10-27-2014 07:07 AM ET (US)
I would probably run new cable myself. Whatever you do make sure there's good abrasion protection for the cables in the tunnel, that the connection is fused/uses a breaker at the battery end, and that if you do use the power posts that they're in a dry, protected location. I would definitely use solder on terminals to make the connections as well.
posted 10-27-2014 07:29 AM ET (US)
I personnaly used the power posts method for the following reasons:
- I have an enclosed dry location to install them.
posted 10-27-2014 09:13 AM ET (US)
If you choose to retain the present cables and extend them, you must realize that you are facing a challenge in the total resistance of the cables. If the present cables are sized so they have a resistance that is just low enough to be tolerated, when you extend those cables you must then use a very large cable with very low resistance so as not to add too much more resistance to the total circuit.
For example, suppose an engine maker says that if the cables are 20-feet long the wire must be 2-AWG. This does not mean that you can make up a cable that is 14-feet of 2-AWG and 6-feet of 4-AWG spliced or connected together and have the equivalent of a single cable 20-feet long of 2-AWG. The spliced cable will have more resistance. The extra resistance comes from both the use of the section of smaller cable and from all the splices and connections.
In many instances the engine will start with cables that have more resistance than specified by the manufacturer, but every increase in resistance in the battery cables brings more voltage drop during starting. And every little drop in voltage adds up. There might come a time when the total resistance is too high, and your engine does not start. Using under-sized cables means you will lose some reserve starting power. If you are willing to pay that price, you can use under-sized cables.
posted 10-27-2014 11:58 AM ET (US)
Thanks for the help. I think I'll leave the battery in the stern. I don't think in my case it's worth the effort. I have other problems to solve on this boat, like converting the side shifter box wiring harness to use in the center console and converting a Honda top shifter to use with my Yamaha C60. See my other thread.
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