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Battery lead/earth wires

Started by _Eddie_ , Jul 12 2008 04:59 PM

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7 replies to this topic

#1 _Eddie_

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Posted 12 July 2008 - 04:59 PM

I'm just looking at tidying up the main battery leads in the engine bay. The new adjusted battery position means I'm going to have to run 2 longer length leads: the main earth to the engine block and the main wire to the starter motor.

I've got some 4 gauge car audio amp wire here which I'm looking at and wondering if it would be suitable? The length of the new Earth wire will be approx 70 cm and the starter motor wire will be around 115 cm. Is 4 gauge enough or do I need thicker?

Also is car audio amp wire suitable or do I need the more sturdy copper? I notice the amp wire has a lot finer and flexible copper strands as opposed to the thicker, more sturdy battery leads.

My brother seems to think the finer wires should run more current?

Anyone wiz za comment?

Edited by Eddie, 12 July 2008 - 05:02 PM.

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#2 antelopeslr5000

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Posted 12 July 2008 - 07:07 PM

Are you talking about 4 AWG wire? I've got my battery located in the boot and I'm using 4 AWG wire which runs all the way up to the starter motor. It's multi-strand designed for audio sytems which allows more flexibility. It has been like that for over 15 years now and I've never had a problem with it.

You won't need more sturdy copper cable, although its insulation maybe more suited to withstanding heat and/or grease, fuel, oils etc which may be present in the engine bay.

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#3 _Eddie_

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Posted 13 July 2008 - 02:17 PM

Ok so you're running 4 AWG gauge all the way from the boot up to the starter and never had any problems? Do you know if the wire gets warm after turning the starter motor over?

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#4 _torbirdie_

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Posted 18 July 2008 - 09:34 AM

4 gauge seems a bit light to me, though the reports of no problems ^ may prove that wrong. (6cyl 0r 8)
What gauge is the conventional wiring, go no smaller. Measure the diameter of the conductor and replace with similar.
Fine strand wire valuable for threading easily though tight areas, otherwise for DC electricity, its only the amount of copper per length of wire that matters.
Given you need to fit quality terminals to the ends of the wires which is half the battle if you just have some spare wire, Id suggest just going along to your auto accessories store and getting the cables at the length you require and that way you'll already have quality terminals.
Also as mentioned, the insulation is likely to be much more heat(especially if it goes anyway near an exhaust(most starters are close to one) and oil resistant.

Edited by torbirdie, 18 July 2008 - 09:35 AM.

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#5 antelopeslr5000

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Posted 18 July 2008 - 02:35 PM

Ok so you're running 4 AWG gauge all the way from the boot up to the starter and never had any problems? Do you know if the wire gets warm after turning the starter motor over?

Well, for the short amount of time it actually takes for my motor (V8 5 litre) to turn over and start, the wire doesn't get warm at all.

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#6 ls2lxhatch

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Posted 18 July 2008 - 07:33 PM

This chart may help.
http://www.emarinein...ors/cables.html

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#7 _UDLOSE_

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Posted 08 August 2008 - 09:45 AM

I've just mounted my battery in the boot and i'm running the cables atm. I'm using 2 gauge, thats what i was recommended.

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#8 Dangerous

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Posted 08 August 2008 - 04:12 PM

4AWG will probably be fine if your engine is not cammy or very modified, and a b1tch to start. The critical part of the cables will be the quality of the terminations on the ends. If you're crimping the terminals on, the the audio cable is good to use, as the many minor copper strands get crushed into a better contact with the terminal than fewer, larger copper strands. Just make sure you use the right sized terminal, and a good quality (and large) crimp tool. If you're soldering, the terminal and solder needs to be pretty hot to create a good strong low resistance join, and the problem is that the many small copper strands are really good heatsinks, so they take away the heat you're trying to apply to solder the terminal. Soldered copper can also be brittle too.

Torbirdie suggests just buying new cables to suit - if you don't have acces to a good crimp tool and crimp terminations, then that's probably the best option.

Also, don't forget about the battery earth to chassis lead - these are never big enough from factory.