Installing a new +ve termal question?

[RemarkLima]

My positive terminal is pretty knackered, I\'ve had to jury righ it a while back so it would hold on OK.

Anyway, thought I\'d get a new terminal and as the rad is out a good time to do a couple of little jobs, so poped to Maplin to get some of the thickest cable they do, 4awg apparently.

And this just about fits into the screw part of the new positive terminal. The one I have looks like:
http://cgi.ebay.co.uk/Automotive-Battery-Terminals-1-pair-New_W0QQitemZ280146563311QQihZ018QQcategoryZ14932QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Now reading around, folks are using 0awg cable to relocate batteries, and the origional connection is solid metal to metal.

So will this be enough? As it\'s only going to be a very short run, should I run 2 cables instead?

Cheers,
Mark

[shaunwil]

Depends on the length of cable, 4awg is only good to carry 75amps over a few meters. I run a pair of 4awg from the boot for my power system and don\'t have any issues. If in doubt just run 2 lines from the battery to the pickup. There is 2 rings you can bolt to.

Shaun

[RemarkLima]

Cheers Shaun,

I\'m not relocating the battery, so it\'s literally a run from the fust box (next to the battery) to the battery, so will be 10cm run absolute max!

The only issue will be starting I guess, but I can runa nother wire if needs be... Do you think I should err on the side of caution? I was looking at the battery cables in halfrauds and they\'re really thin, I was quite surprised.

[shaunwil]

You should be ok with a short length, just look at the cross sectional area of the original pickup, 4awg should be bigger if worked out.

Shaun

[RemarkLima]

OK, starting to get into areas I know little about! But what will happen if it\'s not thick enough? Blow a fuse? Or worse?

I\'ll try it with one cable and see if it needs more

[kev-yorks]

A bit crude but when the systems under max electrical load feed the temp of the cable if its getting warm them upgrade if theres no heat buildup then you should be okay. Or even better if you\'ve access to a multi meter measure if there\'s any voltage drop over the length of the cable.
Kevin

[RemarkLima]

Ah ha, I have a multimeter!

So what do I measure? Do I do a comparision, one from the positive to negative battery terminal (which should be full voltage) and then the same from the end of the cable to the negative terminal?

What\'s an acceptable voltage drop?

[kev-yorks]

When under max load you want to measure for voltage drop across the cable you can do it at either end to earth and compare the readings but the best way is put the multimeter on a low scale and put the probes at either end of the live cable 0.0volts is ideal and what you are after. As the reading goes up then you are getting more voltage loss due to resistance within the cable.
Kevin

[RemarkLima]

So max load, stick on AC, radio, lights on full beam, fogs (front and rear) with the engine running right?

Cool, cheers for that guys, I should be motoring once again by the end of tomorrow evening (providing UPS actually bother to turn up this time!)