Would a worthy concensus then be that I should remove the breaker and simply use a 12 gauge wire that would fry itself acting as the fusible link. It appears that this is all GM used originally also with just a rubber covering over the connection.

 

:yesnod:

 

W/ the CB still in place of the fuseable link(connected to the start JBlk), and the Alt output disconnected, (engien on or off), measure the voltage at the dicaonnected Alt output wire.

Do you have battery voltage there?

No,.... there is a short in rust3 wire somewhere. Run a bypass wire w/ fuseable link from JBlk to Alt out. All should be fine. (Temp fix.)

Yes,... we deal w/ that when it happens.


[Modified by ZylaRace, 11:59 AM 10/4/2002]

 

"Would a worthy concensus then be that I should remove the breaker and simply use a 12 gauge wire that would fry itself acting as the fusible link. It appears that this is all GM used originally also with just a rubber covering over the connection."

Suggest not till you find the problem. You already replaced it once, and it just blew again,.... right? i.e. Have not fixed the problem yet.

 

Yes, I do. Exactly voltage as battery.

 

Replaced it with a 30A fusible link and it blew immediately when the car started. It appears we've decided that is far too small anyways.


[Modified by scorp508, 12:01 PM 10/4/2002]

 

Scorp-

Keep the faith, man. Electrical problems are the worst, and I feel for you dude. Hope you find your answer soon.

 

Ok guys, NAPA has 10 feet of 12 gauge fusible link for $4.49, I'm going to go pick some up now on lunch. Contunue discussing. :D

 

I think some people are getting confuse w/ the gauge wire and the current handling. In the home, (120V), a 10 AWG wire can handle 30Amps. In a car, (12v), a 10AWG wire can handle 300Amps.
The fuseble link being 12AWG, can continuously handle 200Amps. Hence it will eventually melt if +300Amps is pulled thru it.
A 14AWG fuseable link is good for 150Amps continuously.
A 16AWG fuseable link is good for even less.

Gauge and amperage, don't get them confused.

 

Is this the same alternator rating as the one from before the engine replacement. I understand you replaced the alternator, but with the same one? If so, the 30A link worked before, it should work now. Going to a larger rating will risk fire.

Next, you will always read continuity between ground and hot if you have anything in the car that is connected to the battery, like a clock, stereo memory power, alarm, etc. You will read continuity through the components. The real question is, what is the resistance value? If it it near zero, dead short somewhere. If it is several k, probably reading through compents still on line. Remove all the fuses in the fuse block and check again. You can also read through the alternator to ground, but with a high resistance value (not sure what).
Typical voltage values should be around 14.7 from the alternator, not 16.
Take the alternator out of the loop and run the car on batter only, does the link fry?
Connect the field coil power from the fuse block to the alternator, but not the output voltage wire. Read the value at the output. Seem normal?
Get an ammeter and check to see what current leve is flowing.
Start with a fully charged batter, reducing the current requirement to recharge the battery,
Start the car with a fully charged battery and a charger connected to the battery. This will reduce the current required.

Good luck
THEDEVL (flynn) :reddevil

 

A 30Amp fuseable link and or a 30Amp CB on the Alt output,... they should trip or burn right from the get go. The Alt @ idle should be putting out more than 30Amps. (Lights, pump, ignition and all.)

You may be chasing a non problem here.

Replace w/ a correct sized fuseable, may fix things.
As said, if the original was corroded, the corrosion may have caused it to blow. i.e. Not an electrical problem.

 

I think your problem is that one of the starter wires is shorting out. If this only happens when you start the car, it may be because the starter relay energizes the solenoid and this circuit is shorted, causing the link to blow. Once the car is started, relay is off, no power to solenoid, so no short.

You also would not find the short unless you energized the starter relay.

 

<I think some people are getting confuse w/ the gauge wire and the current handling. In the home, (120V), a 10 AWG wire can handle 30Amps.>

Very true but the 120 in your home is a RMS value not DC. You are correct as frequency goes down, capacity goes up. (Or course so does I^2R=loss for a given load)

<In a car, (12v), a 10AWG wire can handle 300Amps.>

Where did you get that data? My engineering handbook doesn't give #10 that kind of respect, even at DC.

 

I just got the 12 gauge fusible link line from NAPA. Looks exactly like the stuff I took off the car. Maybe this will help things. :)

 

Yeah, I figured someone would call me on those numbers, but I'll have to save that for another discussion. Length does come into play. These are valid ball-park numbers for this discussion.

(Yes, I know engineers like to be exact.) :)

 

I know it is not exactly the same but when I was a t ech at an Infiniti dealer our Main Fuse was 100amps.

 

Yep there is a difference between working world and engineering figures. You had me scared for a second. I'm sure you're right on such a short length.

 

One thing to keep in mind also is that a 30a fuse, a 30a fuse link wire, and a 30a circuit breaker will all work differently. A fuse rated at 30a will burn when amperage is 98%of or above 30a.(unless it is a slow burn, not likely here). A circuit breaker rated at 30a will trip when loaded at 100% of or above the 30a rating, and it will reset itself continuing to do so until load is less than that of the rating. A fuse link wire rated at 30a will withstand momentary loads of up to 300%(depending on length of fuselink wire) of the rated 30a, acting like a slow burn fuse. It will take the extreme load until it gets hot enough to burn through. When shorted directly they will burn immediately. That is why a fuselink wire rated 30a(the factory wire) will work and not the 30a breaker or fuse. The alternator will put out, up to it's rating, enough amperage to fill the draw created by the battery when the car is started until the battery is charged back up. It only takes seconds for the alternator to charge the battery, if battery is sufficiently charged prior to starting, back to full charge with just starting the car therefore not enough time to burn a fuselink wire but enough to trip the circuit breaker. Let us know, Scorp, once you replace your circuit breaker with the 12ga fuselink wire if it works or not. I'm thinking that if you have the wires fixed at the starter, you should be OK! :cheers:

 

If I remember right, #12 Cu will gain 1*C at 20A draw. #6 Cu will gain 1*C at 100A draw (in short lenghts). So if I remember this right, I amagine the to actually hit the melt point of a couple inch length of #12 Cu, you would have to draw some serious current!

I think the replacement fusible link was too small (AWG) for the use, and a #12 (to the right length) will work! And as jfb said, 30A will not cut it on a 105A alternator with a low battery.

 

She runs she runs she runs she runs!!!! Replaced the circuit breaker with a length of 12 gauge fusible link I got a NAPA and all seems well. 13.8-14.1 at cruise and no fires. Just got back from a 15 mile drive.