alternator wires caught on fire!

stykthyn · Dec 10, 2007

well, my battery was real low and I had to get a jump start. I was driving for maybe three minutes when I smelled something burning. I pulled over and the popped the hood and the power wire coming off the alt was on fire! it burned my fuse block and several other cables that were close to it. it also toasted the insulation on the bottom of the hood and the paint on the firewall next to the starter relay where I had the fuse block. I suspect the fuse block is where the fire started as it looked the worse. I had a 3g upgrade with a 150a fuse that was run with 4guage wire. anyone know what could have caused it to overload and burn like that? are my cables too large?

bloopbloob · Dec 10, 2007

you can't have too large of cables. the bigger the better. did you have a 4ga ground wire also? how did you wire your 3g? did you have the old power wires hooked up to it, along with the new power wire? if so, thats why. the old power wires can't handle the current the new alt puts out. they dont even need to be (and shouldn't) be hooked up to the new 3g. thats what the new 4ga wire is for.

stykthyn · Dec 10, 2007

no, all the old wiring was gone. I used 4g for the power wire going to the starter relay, and for the ground, which was attached to the batter and went to a point at the bottom of the block. something caused a huge surge and toasted everything.

jrichker · Dec 10, 2007

High resistance connections can cause fires like the one you described. If the connection is loose or corroded, it makes heat, which makes higher resistance and that makes more heat.

stykthyn · Dec 10, 2007

yeah, I figured it was a loose connection. hopefully this next one wont catch fire too.

HISSIN50 · Dec 10, 2007

As I recall, 4 AWG [of a length for a typical alternator retrofit] is rated below 150 amps. I would use a lesser rated fuse next time.

Glad to hear that all in all, you're ok.

stykthyn · Dec 10, 2007

HISSIN50 said:
As I recall, 4 AWG [of a length for a typical alternator retrofit] is rated below 150 amps. I would use a lesser rated fuse next time.

now that is good to know.
I went with the same set up as before, but this time I went with a 100a fuse. I am not running a system or anything else that really requires a 3g(yet). so there should be no reason why it would spike over 100amps. I think that I will build a metal box for the fuse though. I could tell by looking at the old one that the plastic is what caught fire and set everything else off.

bloopbloob · Dec 10, 2007

stykthyn said:
now that is good to know.
I went with the same set up as before, but this time I went with a 100a fuse. I am not running a system or anything else that really requires a 3g(yet). so there should be no reason why it would spike over 100amps. I think that I will build a metal box for the fuse though. I could tell by looking at the old one that the plastic is what caught fire and set everything else off.

hmmm. i'm sure someone will correct me if i'm wrong, but i think the 3g puts out 130 amps.... you might have a prob. running a 100 amp fuse.

Sicarius428 · Dec 10, 2007

I am running a 100A in mine right now. The 100A rating on a fuse is amperage over time so it isn't 100a... its actually more if it doesn't spike.
Kevin

stykthyn · Dec 10, 2007

bloopbloob said:
hmmm. i'm sure someone will correct me if i'm wrong, but i think the 3g puts out 130 amps.... you might have a prob. running a 100 amp fuse.

130 is at full output. I Shouldnt be drawing that much current unless I am at capacity, and with stock electronics I should be far from it.

ninety15.0 · Dec 11, 2007

Yup i am running a 100 amp circuit breaker on my setup. If i draw more than 100 amps...it just clicks off. I can see this happen with the voltage gauge in the car...then i just hop out and reset the breaker...its very convenient.

That being said...it has only tripped once when i was teaching my girl how to drive in a parking lot (lots of REAL low RPM with the lights and heat and radio on)

Shakerhood · Dec 12, 2007

For some Reason PA Performance uses a 200 Amp Fuse in their Power Wire Kit.... Just never seemed correct to me.

stykthyn · Dec 12, 2007

car has been up and running for 2 days now with no problems yet
::knock on wood::

HISSIN50 · Dec 12, 2007

stykthyn said:
.....been up.......for 2 days now with no problems yet
::knock on wood::

Please dont talk about being up two for days straight and knocking on wood in the same thought.

Sicarius428 · Dec 12, 2007

LOL
Kevin

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