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Trunk Battery Cable Size?

18K views 6 replies 5 participants last post by  EOD Guy 
#1 ·
'38 Coupe with chevy 350. Planning to mount battery in the trunk. Planning to wire it with starter cable only hot during cranking. Do you guys think 2 gauge is a sufficient size.


Thanks
Willy
 
#3 ·
I used 1/0 welding cable for my trunk mounted battery - ran both cables, positive and negative, all the way to the starter/block.

There is another recent thread that talks about battery cable size and a few other points. Should still be in the 'today's posts' list.
 
#5 ·
2awg should work just fine. Always, heavier is better up to a point but it is also harder to work with in tight spaces. Welding wire is possibly the best for current transfer as it has many more strands plus is much limper - but I'm not sure of the insulation quality for car use though. I'm using Taylor 2awg in my '31, trunk mounted battery, and have had zero problems.

Do a Google using these terms: ampacity of automotive copper wire
there are literally thousands of good resources, but the first couple pages of any search usually are the best.
 
#7 ·
Here's the post from Gonzo

professional electrician here. unless you are running 20ft of wire or more 4ga wire will suffice. you can buy 4ga THHN from home depot or lowe's but its expensive and doesn't bend as easily as welding cable but the insulation is rated for outdoor use and burial, very u/v resistant. good wire overall. the number of strands and it's relationship to current carrying capacity is null. 4gauge wire(bare) is rated for 100 amps whether it's THHN, SOOW, or type W. If you can find EPDM that would be the best for automotive use if you are that particular about it. the types of wire insulation will also determine the ampacity of the wire. 4ga SOOW is not rated for 100 amps, its rated at 65. the insulation has to be able to safely transfer the heat created by the load. SOOW is low cost compared to type W(100 amp rating). insulation specs also address environmental issues that can de-rate the wire. however, for the application in question, 4ga ANYTHING will work. unless its bare copper(duh). my personal preference in my camaro is 2ga EPDM because i have access to it for free. it's fine strand, dissipates heat well, takes the harsh underhood environment, and is more than big enough. the specific resistance of copper doesnt change with strand consistency (fine/coarse). the disadvantage of fine strand is when it starts to corrode it ampacity goes to hell in a handbasket quickly because of the air gaps between the strands. but if you seal the wire ends with a good heat shrink with adheisive like 3M you should never have a problem. fine strand wire handles heat dissipation better than, say, THHN(coarse). unless you are running 8 million watts of electrical crap you wont need to worry about heat from amp draw. clean connections, good grounds (size them as you would + wire), and good wire and you're all set. and yes you can use welding cable.
 
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