how many amps shoud the car take?

[Stegs]

ok guys, had a voltage go bad on me and melted a wire in the fuse block

anyway, long story short

I fixed everything up and put a in-line fuse to protect it if a regulator ever goes bad again

right now the in-line fuse wire can handle 40 amps

the fuse is a 20 amp fuse, my theory is the 20 amp fuse will give up first, therefore saving me from chasing melted wires

my question is this : If the battery is calling for a charge, what is the max the voltage regulator will allow?

last night I started the car, and the amp gauge was discharging ....I checked and I blew the 20 amp fuse....no big deal.....but I want to know if 25 amps is max or 30? where does the regulator stop?

[Pete in NH]

The voltage regulator should keep the system voltage between about 13.8 to 14.5 volts. The regulator does not really directly control the available current. That is more a function of what the maximum current the alternator can put out.

There should be a fusible link between the battery stud on the starter relay and a bulk head connector pin. This should be a blue colored 16 gauge link and they can handle something between 50 and 60 amps. A 20 to 30 amp in line fuse will very likely not be large enough at times and will blow out. A stock alternator on a 69 with A/C was good for about 45 amps. Re-builders today often mix and match parts and create alternators Chrysler never really built and the new rebuilds might be good for more current.

Do you have any idea why the original wiring insulation melted?

[Stegs]

The voltage regulator should keep the system voltage between about 13.8 to 14.5 volts. The regulator does not really directly control the available current. That is more a function of what the maximum current the alternator can put out.

There should be a fusible link between the battery stud on the starter relay and a bulk head connector pin. This should be a blue colored 16 gauge link and they can handle something between 50 and 60 amps. A 20 to 30 amp in line fuse will very likely not be large enough at times and will blow out. A stock alternator on a 69 with A/C was good for about 45 amps. Re-builders today often mix and match parts and create alternators Chrysler never really built and the new rebuilds might be good for more current.

Do you have any idea why the original wiring insulation melted?

Alternator was not charging....so I brought it in to have it rebuilt. They tested the battery and it had a bad cell, so they replaced that...

Next they tested the regulator.....said mine was bad so they put a new one on.

After all this my car still would not charge.....they said it was the alternator ( like I told them in the first place)

So they rebuild it to stock specs, turn on my car and the red wire that come from the alternator and regulator melted going into the fuse block on the fire wall.....

I ended up having to drop my steering column to get at the fuse block from the inside.....where I found that wire was melted about 1 inch in......rest was fine.

So I replaced it but put in a inline fuse after the regulator in case it fails again......thus way it will blow the fuse and not melt my fuse block

I blew a 20 amp fuse last night.....I have some 30 amps to try.....but im curious why if I have a fuse already....why didnt that blow before my wire got hot?

[billschroeder5842]

Here is my .02...

First my '69 Charger had a few issues like this. Fortunately (Finger crossed) my 75 RR has none of these issues.

My quick thought is with mixing and matching electrical component you may have a combination of new/old, high voltage/low voltage regulators, alternators, fuses, wires (the old wires are hell) fuses.

My thought is to tackle the situation by brining everything back to stock.

Short in the "New" alternator?

Sorry, Dude...electrical issues are tough.

[Stegs]

its fixed now...I used the same guage wire that was in there, all I did was replace the melted wire with new, and thru a inline fuse.....

like I said I blew a 20 amp fuse, but no big deal.....I will get some 25 amps, if I go thru those...ill move to a 30 amp


I know the wire I used is good for 40 amps....my goal of course is to have the fuse blow before the wire melts....down the road id love to get a painless performance wiring harness and redo it...but I hate electrical stuff 

[Pete in NH]

A suggestion for you. Make sure the fusible link is still in your car. Many get replaced with plain, old wire when they blow and people don't know what the fusible link really is. The fusible link is the main fuse for the car's electrical system in the charging circuit path and you want to make sure it's there.

On your fuse block issue, I suspect the wire insulation may have melted due to a bad connection that caused a lot of excessive heat. There are a lot of quick plug on connectors on the fuse block and riveted connection bars. As these connections age and get loose over time they form poor connections that get hot. The hotter they get the poorer the connection gets and things really get hot. I would take a careful look at all the fuse block connectors and clean and tighten them up as required.

[Stegs]

A suggestion for you. Make sure the fusible link is still in your car. Many get replaced with plain, old wire when they blow and people don't know what the fusible link really is. The fusible link is the main fuse for the car's electrical system in the charging circuit path and you want to make sure it's there.

On your fuse block issue, I suspect the wire insulation may have melted due to a bad connection that caused a lot of excessive heat. There are a lot of quick plug on connectors on the fuse block and riveted connection bars. As these connections age and get loose over time they form poor connections that get hot. The hotter they get the poorer the connection gets and things really get hot. I would take a careful look at all the fuse block connectors and clean and tighten them up as required.

I looked at the fuse block when I had it out, everything seems fine...connections seem tight


but where do I find this "main fuse" for the car? obviously mine isn't working b/c the inline fuse I installed blows every now and then....

where do I find this main fuse to save my car from melting?

[Pete in NH]

Your car left the factory with a fusible link installed between the 5/16" battery stud on the starter relay and one of the bulk head connector pins. Look for a dark blue wire between that battery stud and a bulk head connector pin. It may have a little molded on flag tab that says Link or Fuse. If what is there is any other color than dark blue some one has likely replaced the fuse link with a plain piece of wire. The original link is a piece of special 16 gauge wire covered by a high temperature type of insulation that is in the main charging circuit and is meant as a last ditch safety measure to prevent a fire or wiring melt down.

[john108]

Try this picture

[john108]

And This

[Stegs]

And This

yea my car does not have that at all.......how many amp fuse is that? I have a 30 amp inline fuse now...seems to be holding so far

[Pete in NH]

Stegs,

What does your car have in that place between the starter relay and bulk head connector?

As I said, those fusible links were intended as sort of last ditch fire protection. They are not very precise devices.  Since the cars originally had 45 amp max. alternators, I suspect those links would melt somewhere between 50 and 60 amps. That's somewhat of a guess because as I said they were rather crude devices. A more modern and controlled fuse is a big blade type fuse used on newer cars. One type is called a Maxi-Fuse and with a stock alternator, a 50 or 60 amp one mounted in a plug in holder would be a good substitute for that fusible link. You can also find ready made fusible links for your car with the 5/16" ring terminal on one end and the bulk head connector pin on the other. Various Mopar restoration suppliers carry them although some are a bit pricey.

[Stegs]

I looked tonight and I do have that fuse.....but here is something wierd...

how does it work.....b.c when my regulator failed...I melted a wire.....shouldnt this have saved it?

also 45 amp max?

Im running a 30 amp inline fuse now with no problems!

[Pete in NH]

That's the problem with fusible links, they don't always melt when they should have. As I mentioned they are a very crude way to protect the car from a total melt down and fire. You might want to up grade your 30 amp fuse to 40 or 50 amps. 30 is a little close and it may blow at times when nothing is really wrong.

[Stegs]

That's the problem with fusible links, they don't always melt when they should have. As I mentioned they are a very crude way to protect the car from a total melt down and fire. You might want to up grade your 30 amp fuse to 40 or 50 amps. 30 is a little close and it may blow at times when nothing is really wrong.

well I ran 12 gauge wire, same as the wire that melted....

I was told by the guy at napa it will handle 40 amps before it gets hot....I want the fuse to blow before I melt the wire....hints why I have a 30 amp...maybe I will go to a 35 amp....but I want the fuse to blow before the wire melts

[A383Wing]

I looked tonight and I do have that fuse.....but here is something wierd...

how does it work.....b.c when my regulator failed...I melted a wire.....shouldnt this have saved it?

I melted the ignition wire between regulator and ignition switch a few years ago when regulator failed...I had to perform surgery to replace that wire that ran to regulator. I also put an inline fuse at the regulator to protect in case this happens again

[green69rt]

This site gives a reference for AWG vs current capacity.   Looks pretty conservative.

http://www.keywolf.com/American_Wire_Gauge.php

[Stegs]

I looked tonight and I do have that fuse.....but here is something wierd...

how does it work.....b.c when my regulator failed...I melted a wire.....shouldnt this have saved it?

I melted the ignition wire between regulator and ignition switch a few years ago when regulator failed...I had to perform surgery to replace that wire that ran to regulator. I also put an inline fuse at the regulator to protect in case this happens again

that's almost exactly what I did, except my fuse is near the fuse block itself...so far so good...as long as the battery is full charge!

[el dub]

That's the problem with fusible links, they don't always melt when they should have. As I mentioned they are a very crude way to protect the car from a total melt down and fire. You might want to up grade your 30 amp fuse to 40 or 50 amps. 30 is a little close and it may blow at times when nothing is really wrong.

well I ran 12 gauge wire, same as the wire that melted....

I was told by the guy at napa it will handle 40 amps before it gets hot....I want the fuse to blow before I melt the wire....hints why I have a 30 amp...maybe I will go to a 35 amp....but I want the fuse to blow before the wire melts

The guy at napa doesn't know squat. Go out to your house panel and check out your 20 amp breakers. They will have #12 wire going to them. Per NEC. Or maybe I don't know squat.

[Pete in NH]

A 12 gauge wire will handle 40 amps but, it's going to get a bit warm if it does it for very long. The NEC calls out 20 amps on #12 wire in house wiring because you don't want it to get too warm inside walls and your wall outlets would get very unhappy dealing with 40 amps.

A short piece of #12 handling 40 amps for a short period in a car is okay but, if the circuit was going to handle 40 amps continuously #10 or #8 would be much better.

[Stegs]

A 12 gauge wire will handle 40 amps but, it's going to get a bit warm if it does it for very long. The NEC calls out 20 amps on #12 wire in house wiring because you don't want it to get too warm inside walls and your wall outlets would get very unhappy dealing with 40 amps.

A short piece of #12 handling 40 amps for a short period in a car is okay but, if the circuit was going to handle 40 amps continuously #10 or #8 would be much better.

ok, but like I said earlier, I guess if it can handle 40 amps for a short period of time, that's fine....my goal is if something goes bad, to have the fuse blow

Im running a 30 amp fuse now, and as long as the battery is fully charged, it works perfect. I can run all my lights and turn signals and it wont blow.....