This thread should be pinned for the purpose of showing how not to do a sound system install. Your mate was very lucky his car didn't catch fire.

There is one single wire in a stock wiring system which has no fuse. It runs from the positive battery terminal to the starter. Unless the battery is in the trunk it is like 2 feet long, tops. It is like... 4 gauge? I don't remember gauge versus square mm. Say 25 square mm. It is able to transmit upwards 300 amps for the short time it takes to crank the engine. It is run in a secured route to avoid short sircuit, even in case of an accident.

Installing waterhose-sized wires in a car is retarded. End of story, I have nothing more to add. That is; I do but this post is too long already.

 

There is nothing wrong with running O awg wire as long it is fused properly and "terminated" well.

When you say that your friend added that 0 gauge himself that leads me to believe that he did not crimp and solder it properly. When you don't do this you develop and intermittent contact similar to the old aluminum wiring in homes. It leads to arcing and large transfer of amps via wire to crimp lug. That is exactly what happened to your friend's car.

I can tell by looking that the lug was not crimped well for that wire.

Proper way is to, apply solder past to the wire (stranded), hydraulically crimp the lug and then heat the connection so you effectively have a solid connection. That is the professional way of making a solid electrical connection.

 

No soldering! That is extremely old-school wiring. Crimping only.

Yel-low, would you care to explain the purpose of the 0 gauge? I mean; even a high output alternator produces say 150 amps max, but hardly continously. If it does; to which purpose?

 

Ah thanks guys. It wasn't crimped like it should have been. I pulled the metal piece (lug) right out of it when I got it out of the car.

 

I would never just crimp any sort of connection. Remember the old days were everyone used those old ass butt connectors and then wondered why in the hell when they beat on the underside of their dash their alarm all of a sudden worked again. (ie Best buy, Circuit city, run of the mill alarm installers)

Crimping is just lazy.


Voltage travels on the outer surface of a conductor. Amperage flow on the other hand is correlated to the cross section of a conductor. This is why power lines and grids step up their voltages on relatively low gauge wire for long runs and then bring it back down to higher amp lower voltage at the transformer side. Lower losses..

0 gauge is a bit overkill for a system with just two amps never-the-less. The whole car stereo electrical debate had been greatly hyped up but I don't blame the guys. Everyone is just trying to make a buck at the end of the day. If they (manufacturers, re-sellers, installers) successfully convinced you that you need 0 gauge wire in your car with a couple amps then they did their job in my eyes.

Edit: if you produce 150amps on a conductor rate for 100amp even for a mere millisecond; you have effectively created a "fuseable link". You may get away but the sheer tolerance built into the wire from the manufacture but not for too long.

 

Nice. Thanks again Yel-low.

 

I totally agree with yel-low here. I always solder whenever possible and have never had an electrical problem. Especially in a car environment where there are lots of temperature changes and vibrations. Soldering certainly can't hurt anything. Not to mention it's just fun to superheat metal to a liquid and fuse two wires!

 

I sometimes solder connections too. But never high current applications. I've repaired equipment ranging from CD players to huge CNC machines due to soldering points going bad on printboards. And with crimping I mean proper crimping with proper tools and correct size for the wire.

Trust me, soldering is a huge tabu when it comes to wiring as is buildings. It has surely caused many casualties from fires through the years too, because it was common in the 60ies and earlier.

Now I'm done with my rant

I stand by my statement though; 0 gauge is retarded

 

I sometimes solder connections too. But never high current applications. I've repaired equipment ranging from CD players to huge CNC machines due to soldering points going bad on printboards. And with crimping I mean proper crimping with proper tools and correct size for the wire.

Trust me, soldering is a huge tabu when it comes to wiring as is buildings. It has surely caused many casualties from fires through the years too, because it was common in the 60ies and earlier.

Now I'm done with my rant

I stand by my statement though; 0 gauge is retarded [/b]

Why does it cause fire?

The problem with contacts or wiring is the voltage drop on them. If you have 1 ohm resistance between two points (say battery and alternator) the voltage drop on the wire would be 100V at 100 ampere current. Of course the current will never reach to 100A in that case (it would rather be around 12A). If you have 0.01 ohm in between you still have 1V drop on the wire. That means if the alternator side is 14V then the battery side would be at 13V.

Resistance is linear and frequency independent in most automobile applications. So you can measure the resistance between two points with a simple multimeter. Then calculate the maximum voltage drop given the max current the wire will carry:

V(voltage drop)= I(current) x R(wire+connection resistance)

For small resistance measurements just be sure the multimeter reads 0 ohm when shorted. And the datasheet of the multimeter should give the minimum reliable resistance measurable.

For example if you have a 200W amp the most current it can draw at 10V is 20A. This number is prolly highly exaggerated since the internal capacitance of the amp would soften the current peaks. Gauge 5 wire resistance is 1ohm/km. Lets say you have 10m wire between battery and trunk (amp) so the wire resistance is 0.01ohm. Lets assume you have perfect connections = no connection resistance. The voltage drop on the wire would be 20 x 0.01 = 0.2V. This is very low even with pessimistic values, actually its an overkill if you ask me. In this example there is no point using thicker wire. But watch out the connection resistances.

 

i am royaly confubaled. :lol: where is drew's comment?

 

Saint, you said it yourself. Connector resistance can over time cause solder meltdown. Which again causes PVC wire insulation to produce acid when in contact with damp air if heated beyond 70 degrees C. That leads to corrosion which again further increases the connector resistance. Untill it catches fire, if there are flammable objects nearby. Like wood houses.

I recommend voltage drop measurements in favour of resistance.

 

Saint, you said it yourself. Connector resistance can over time cause solder meltdown. Which again causes PVC wire insulation to produce acid when in contact with damp air if heated beyond 70 degrees C. That leads to corrosion which again further increases the connector resistance. Untill it catches fire, if there are flammable objects nearby. Like wood houses.

I recommend voltage drop measurements in favour of resistance.[/b]

Only 70C?

Voltage drop test looks easier. Thanks for clarification sir

 

Home and auto environments practice very different disciplines due to the nature of the environment.

 

OMG guys I was totally lost. Glad goliat was lost too. BTW where the hell is Drew? You guys really know your shit. This is soooo far out of my league. Started at Saints post an came down reading and just started scratchin my goatee. Im glad nobody could see the dumbass look on my face at this point. Hmm... time to wiki this Amp and voltage stuff... B)

 

Haha ME, such matters are the playground of Saint and me, and other electrical engineers.

Saint, 70 degrees is the highest permitted temperature with PVC insulation. Acid "sweat" kicks in slightly higher, in the region of 75 degrees IIRC. And voltage measurement is a far more reliable method with reasonably priced multimetres. Resistance is'nt really measured; it's calculated by the instrument based on an applied voltage and the resulting current. With the mediocre internal power source (some battery in various condition) in mind there is no wonder resistance measurement have generous (read crappy) tolerances in most handheld instruments.

 

:huh:

 

Haha ME, such matters are the playground of Saint and me, and other electrical engineers.[/b]

If only I have to multiply stuff only during the day

 

Engineers are very strange people...

 

I agree, BUT they are also very knowledgeable and friendly. :lol:

 

Engineers are very strange people... [/b]

Your statement blends well with your signature

 

Engineers are very strange people... [/b]

Self awareness is a very important trait

 

What????....

I'm not denying it, just stating the obvious.

Just like surgeons can do the whole blood and gore thing... engineers like ripping the guts out of everything and anything... even if it ain't broke! YET!!

 

LMAO Yel-low...!

 

:lol: Speak for yourself Yel-low

Never mess with things that works is my approach

 

My motto.. "If it isn't broken; I can make it better!"

I fix everything even if it takes me an entire weekend and the item only costs $8.99 to replace. If I can't fix it, I strip it down to "components" that I file away in my parts bins for later use. I NEVER throw anything away.

Even broken, I find value in even the simplest of of things.