alternator/wire issue...wtf

[EGTT91]

So, brought the P5 to a car show today and had the car idling with the subs pounding for about 20 mins... when i first got there and was wipin it down.

So i shut it down, and 3 hrs later when i head home ... i have the battery light on.. so im thinkin FUCKKK i gotta make it home... so i shut everything off, not holding the brakes @ stop lights u know.. saving as much energy as i can.

Get home and the power feed wire bolted to the alternator was MELTED OFF.

First of all , why the hell is it so damn thin??? its like a 12-14 gauge @ absolute best.

So i head out in the scion and pick up 5ft of 6 guage wire and some eyelets to attatch to both ends.

Stripped one end

Crimped on an Eyelet

Ran it thru to the alternator and bolted it on

Behind the motor

Under the battery tray

and up to the main fuse with another eyelet.

Fire it up to find out the new alternator that the guy i got it from put in is shot too... so alternator 2moro!

 

[EGTT91]

i know these things eat alternators like they eat headlights but still, anyone had this issue with the melting??

 

[sethro_GT]

my 88 mx6gt did the exact same thing. I repaired it the exact same way. Corrosion is to blame. Resistance disapates heat, more resistance, more heat. The alt was shoving more and more current through the resistor (used to be a wire, now a resistor) to meet the needs of the car till the wire just burns in half.

 

[StealthWyvern]

my 88 mx6gt did the exact same thing. I repaired it the exact same way. Corrosion is to blame. Resistance disapates heat, more resistance, more heat. The alt was shoving more and more current through the resistor (used to be a wire, now a resistor) to meet the needs of the car till the wire just burns in half.

Makes sense! You wouldnt think a little bit of corrosion would make that big of an impact.

i know these things eat alternators like they eat headlights but still, anyone had this issue with the melting??

They do? My last p5 has the orig alt at 170k miles! Now my MSP well the alt was just changed here recenetly but I think the trans shop did something to the car when they had it. What are the chances of me needing a new alt, batt, and trans all at the same time. The batt and alt appeared fine when i dropped it off at the shop to rebuild the trans.

 

[hornsfan10609]

i know these things eat alternators like they eat headlights but still, anyone had this issue with the melting??

Is your battery mounted in the trunk or somewhere else? If so it would clean up the engine bay a lot to remove the battery tray, if not nevermind.

 

[xDJ DUBx]

Damn, judging by your amp wire, you don't seem to even be pushing a big system. This makes me nervous, I run a 4ga wire and a circuit breaker cause they don't make glass fuses big enough. I hardly bump anymore but still, sometimes at meets or something, I'll run the car and bump just the same. I'm gonna keep an eye on mine now.

 

[EGTT91]

no not @ all, its a 500w amp and 2 12's... and honestly my gains are maybe @ best half way up, But I called the guy i got the car from... since the alternator was new i figured he'd have warranty on it.

He tells me this happened to him once before!

oh and hornsfan, my battery is still in the stock location, just pulled it for more room for the fat arms lol

I got an alternator from a B8 90 protege,from a friend of mine same exact thing just gotta swap pulleys and put it in

 

[flash75]

my 88 mx6gt did the exact same thing. I repaired it the exact same way. Corrosion is to blame. Resistance disapates heat, more resistance, more heat. The alt was shoving more and more current through the resistor (used to be a wire, now a resistor) to meet the needs of the car till the wire just burns in half.

That information isn't correct. More resistance reduces current flow. The alternator doesn't control how much current goes through a circuit. The components in the circuit determine current flow.

Example; According to ohms law I (current)=E (voltage) divided by R (ohms). Assume you have a 2 ohm sender fed by a new wire with no resistance. E=12 volts battery voltage. 12/2 equals 6 amps current. Now assume an old wire with 4 ohms resistance. The circuit now has the resistance of the sender plus the resistance of the old wire.
2+4=6 ohms. 12/6=2 amps current. By adding the resistance in the wire current flow is reduced from 6 to 2 amps. Just the opposite of what you said.

I realize the alternator operates at around 14 volts, the results would be different due to the higher alternator voltage, but the current would still be reduced by a wire with resistance.

Wires like the one shown burn out by having a short circuit or servere overloading.

Clifton

 

[sethro_GT]

My 88 mx6GT had a small amp and no other non-stock electrical loads. I replaced the cable and it never happened again. A short or constant overload big enough to do that would have made itself apparent. I rebutted your claim on the other thread.

 

[youngbull]

the wire wouldnt be the resistor. the corrosion at other end would be. and the current trying to go through the wire would overheat it. resistance generates heat, not disapate it. corrosion could be causing the wire , which may be say 10 strands. to have the current flowing through say 4 strands. too much current going through too few strands is a bottle neck, or resistance=heat.
becasue alt is still tech connected to battery and rest of circuit it would sense need and still send out alot of current to try and charge batt.