Quote:
Originally posted by svxistentialist
Yours and mine are both Japanese spec. Possibly the US spec has either higher resistance in the looms[which are certainly different], or possibly a different rating alternator, or maybe a combination of both. ...snip...
Joe
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Joe,
On the North American version's stock wiring loom the minimum expected voltage drop would be about 0.3V from alternator to battery. Changing to 4 gauge (the recommended mod) reduces that to ~0.1V. Admittedly not much, but remember this drop doesn't account for corrosion on connections, etc. which would presumably be less on the bigger wire.
The stock US version uses a wire from alternator to battery of 8 gauge (and maybe even less - just my guess from looking at it), about 5 ft in length, while the alternator is rated at 95 amps. The table I attached was lifted from a solar energy company concerning 12V power distribution. You can see that 6 gauge is the recommended minimum and why 4 gauge (with eventual corrosion impact on conduction) makes sense.
Please note the full mod isn't just for the ground/earthing strap. The OEM system is 4 gauge from battery to engine block (by starter), and 8 gauge from battery to body. The latter is very short (less than 1 foot) and so is probably quite alright as is. The mod is really for the alt - battery leg. AND a correct mod would also employ an added fuse or fusible link rated appropriately to avoid danger from fire in a collision or other damage to the electrical system.
BTW, using European sizes (I have no idea which system the UK is on), 8 gauge=10mm^2, and 4 gauge=25mm^2 (both I believe correct to first decimal point in rounding). If it wasn't obvious, smaller gauge means bigger wire in the US system.
cheers