Running a ground wire for a trunk subwoofer

[wrybread]

> It’s the one with 12 volts on it in reverse gear, with the ignition on…

Ha good point. I guess it would be easy enough to get a multimeter inside that connector.

[MrAl]

if you increase the cross sectional area you can get a huge tub of butter to conduct well

And THAT's why they call you Mr Amp!

Hi,

Oh ok, not sure who that is, but ok

It is interesting that dirt is not really that good of a conductor when compared to copper or even steel really, yet you can conduct thousands of amps through the dirt of the earth because it has a huge cross sectional area. I think it was Nikola Tesla who had dreams of powering the whole planet with this concept in mind but i think he ran out of investors.

Anyway, here is short table of voltage drops and power loss and percent power loss for some AWG wirre gauges.
The power loss is the actual power loss, the percent power loss is the percent of the total power loss and is a good indication of how good the wire is for delivering power to the load.
The figures are based on a nominal 10 amps and 10 feet of wire, but the 10 amps actually drops because of the wire resistance (as well as the voltage). Also, using the chassis of the car as the ground return. Interesting, using another wire for the ground will produce more power loss which could be 4 times as much s using a single wire and chassis ground

Now even though some of the numbers are higher it is good to think in terms of the practical significance of the power loss rather than just some absolute power level..
For example, the AWG 16 wire creates a power loss of about 7 percent, which may seem like a lot. But if you dont use the amplifier at full power then if you turn the volume up a little more you would get the same volume as with AWG 14 wire.
AWG 16 would be the minimum i would say for 10 amps, but AWG 14 would be better. Going to AWG 12 might be a waste unless you always need to crank up to full volume. Any wire size less than AWG 12 is going to be a total waste unless you have some other concurrent problem.

In the table, Ploss is the actual power loss, PercentPLoss is the percent power loss. cmils is the circular mils which is a measure of the cross sectional area and thus the current handling capability. Everything else should be clear.
The wire specifications are based on the mathematical power calculation for AWG wires and so may be very slightly different then for real life wires but this difference will be insignificant for any application.

[wrybread]

Thanks for that, I'll give some graphite lube a try.

And I was wondering, does anyone know if it's possible to break my key cylendar so it moves easily? I don't really care about being high security, and the key has the immobilizer anyway. Would be fine if my key cyclender turned with a screwdriver (or an ill fitting key).

[kallekula]

Copied from the interwebs:

“… the distance between the amplifier and the grounding point should be no more than 18 inches, the shorter the length of wire the better. The gauge of the ground wire must match the gauge of the power wire to assure proper current flow.”