Let’s talk fuseable links. I need schooled.

[70ChargerRT]

Your description is confusing. Seeing more of what you are working on might help in giving you an answer.

Your description is confusing. Seeing more of what you are working on might help in giving you an ansDor

Got this from another thread. You can see the yellow fused link at the starter relay. Is this what you popped?
View attachment 1447104
Here is another view of a popped link.

View attachment 1447105

Yes that’s it. I didn’t completely pop it but it melted it pretty good and that’s exactly how I had it hooked up. Like I said. I just forgot to hook the starter cable up when I tried to start it.

 

[70ChargerRT]

IMO....two gauges smaller...too small and you run a risk of excessive voltage drop thru the undersized lknk.
If appearance is not important, use commercially available fuses like a mega fuse as they provide predictable operation, sized for proper protection based on amperage.
BOB RENTON

So base it on the 130 Amp alt?

 

[70ChargerRT]

Starter motor? Or starter relay?

Starter Motor line doesn’t get fuse link. The load the motor sucks will be able to blow any regular fuse/fuse link you install. The fuse links protects the line running to the cab using the relay stud just as junction point to split the power to the cab and to the motor solenoid into the relay. Doesn’t even protect the starter motor solenoid, just the line running to the cab on the original design.

Relay like I mentioned. I forgot and left the battery cable off of the starter while I tried to start it and smoked the fusible link that’s connected to the 8 gauge battery wire. Everything is hooked up correctly at the relay. I just also read somewhere also that the fusible link protects the 12 gauge wires inside the cab that you should stick with a 16 gauge fusible link. What do you think. Like I mentioned I have a 130 amp alt, 4 gauge wire from alt to battery position, 8 gauge from battery to starter relay.

 

[70ChargerRT]

I'm confused. 2 awg wire is a bit of odd ball size. But is thicker than 4 awg is it not? 0/1 usually being largest for most automotive applications and usually used for some serious aftermarket stereo stuff ?

2 awg is generally used mostly I believe for welding cable. For my 2 awg and 4 awg I used welding cable except for my amp. I used whatever 4 awg that crutchfield sent me.

 

[snakeoil24]

Delco inventor of fusible links specifies 4 gauges smaller not 2

 

[HawkRod]

I am almost afraid to get into this because it could become complicated...

(This is not necessarily directed at the OP becuase I don't know how his system is designed.)

A fusible link and fuses should be sized for the weakest link in the electrical system, not the most powerful. For example, if a person is still routing power in through the Packard (spade) connections through the firewall, then these are rated for about 35 Amps. Lots of old cars have the termination block at the firewall melted due to someone throwing on a much more powerful alternator without considering the downstream effects. The wire gauge sizes in any given circuit also need to be increased if you are putting more power through them.

An analogy is putting in a huge horsepower engine but leaving the transmission and driveline stock - you are asking for trouble. The electrical system is no different. Those that don't respect the need for a carefully planned electrical system often end up with fires or at least electrical issues.

 

[BigFlo]

That’s not entirely true. A 130A alternator will not send any more current to the electrical system than a 65A alternator, UNLESS the accessories in the car demand it. Alternators provide variable current, only up to the demand of the total system accessories that are powered on at the time, plus the amount needed to keep the battery charged. You won’t melt wires/connectors just because you put in a larger alternator if all else remains the same. You can melt wires for several reasons but largely it happens as you said - when you add accessories and don’t upgrade the wiring to handle the additional current demand.

Fuses and fusible links are used to protect the circuit that they are in. The need to be sized correctly, according to the load they are protecting (and assuming all of the wiring is sized appropriately to handle that load).

 

[HawkRod]

A 130A alternator will not send any more current to the electrical system than a 65A alternator, UNLESS the accessories in the car demand it. Alternators provide variable current, only up to the demand of the total system accessories that are powered on at the time, plus the amount needed to keep the battery charged. You won’t melt wires/connectors just because you put in a larger alternator if all else remains the same.

Yes, I fully agree with you, and I didn't specifically state that.

But in a way, that's like saying you don't need to upgrade your transmission if you put a 700 HP engine in the car and never put your foot to the floor! Invariably someone will put a high power radio in the car (or already did), upgrade the headlights or put other items that put a significant additional load on the system. It is likely why they upgraded the alternator!

Regardless, I think we agree that the electrical system needs to be sized and protected based on the potential load it will be carrying.

 

[70ChargerRT]

This a 70 Charger that has all
of the factory wiring but it’s all brand new M&H. I probably have 1000 miles on the car with 130 amp alt with no problems until I made a mistake but I haven’t tried my other accessories though but the fan and Sniper. It’s a 130 amp 3 wire with the upgraded voltage regulator. I put a 4 gauge wire from the alt post to the battery positive and grounded the alt itself. It has dual E-Fans, Sniper, Vintage Air, Big Stereo with 700 amp, dual power seats, Vacuum pump, Dakota digital gauges and LED for lighting. Everything but the vacuum pump, Dakota gauges and Stereo has relays but they are all fused.

 

[Canadian1968]

2 awg is generally used mostly I believe for welding cable. For my 2 awg and 4 awg I used welding cable except for my amp. I used whatever 4 awg that crutchfield sent me.

i was just getting confused with the wording. Makes sense now !

 

[4406bbl]

I am thinking that fuse link was on its way out already and it was just time. The starter positive wire being off should have done nothing. The fuse link should never be larger with stock cab wiring. Maybe you have the stock black wire hooked up at the alternator, along with your bypass wire and got a back feed, unlikely, or somehow you have a high draw accessory on that line, or it grounded while it was unhooked, only way I can see that happening.

 

[HawkRod]

This a 70 Charger that has all
of the factory wiring but it’s all brand new M&H. I probably have 1000 miles on the car with 130 amp alt with no problems until I made a mistake but I haven’t tried my other accessories though but the fan and Sniper. It’s a 130 amp 3 wire with the upgraded voltage regulator. I put a 4 gauge wire from the alt post to the battery positive and grounded the alt itself. It has dual E-Fans, Sniper, Vintage Air, Big Stereo with 700 amp, dual power seats, Vacuum pump, Dakota digital gauges and LED for lighting. Everything but the vacuum pump, Dakota gauges and Stereo has relays but they are all fused.

You say you have a 4 gauge wire going from your alternator to your battery - so have you disconnected the alternator gauge in the instrument cluster? With stock wiring the alternator charges the battery through the alternator gauge in the instrument cluster.

At any rate, you have a lot of high power addons. The fans especially draw lots of amps, as may the radio if you really crank it up. If you truly have "factory wiring" you are playing with fire routing that through the factory wiring. If you used relays and other methods you might be OK (obviously you didn't used factory wiring for the fans since there were none originally). I can't tell from my keyboard how you wired your system.

But take a look at a simple wire gauge chart to be sure you are OK. Here is a simple one I found quickly on the internet.

I'm not trying to bust your chops about your wiring. Neither am I trying to be some perfect goody two shoes about the wiring either. But there are enough examples of cars burning up due to wiring issues, so be sure you know what you are doing with your car's wiring and respect electricity.

 

[diesel_lv]

This a 70 Charger that has all
of the factory wiring but it’s all brand new M&H. I probably have 1000 miles on the car with 130 amp alt with no problems until I made a mistake but I haven’t tried my other accessories though but the fan and Sniper. It’s a 130 amp 3 wire with the upgraded voltage regulator. I put a 4 gauge wire from the alt post to the battery positive and grounded the alt itself. It has dual E-Fans, Sniper, Vintage Air, Big Stereo with 700 amp, dual power seats, Vacuum pump, Dakota digital gauges and LED for lighting. Everything but the vacuum pump, Dakota gauges and Stereo has relays but they are all fused.

I have FI, 3 amps, and the rest factory accessories, a/c etc... 135 amp alternator. I used to have 2 e-fans also. I melted my fusible link due to amperage "draw". I could have redone all the wiring to starter relay w higher gauge and larger fusible link, but for me the easiest route was go directly from alternator to battery, large 2ga cable. Then a post for amps, FI and e-fans to wire directly for their "hot" feed relays. Then the stock cable from battery that splits for starter and starter relay. This way there is no "thru" power draw at relay except for the factory accessories. No issues since.

 

[RJRENTON]

So base it on the 130 Amp alt?

The fuse or fusable link size should be based on the size or amperage of the circuit being protected. Typically, between 135%-150% of the circuit amps, rounded to the closest available amp fuse. For example, if the circuit was rated @ 60 amps, the fuse size would be/should be: 135%= 81 amp fuse. Or 150%= 90 amp fuse.
Every one notes that if using a fusable link for protection, size the link two sizes SMALLER than main wire....but no one states the LENGTH OF THE LINK WIRE or what TYPE OF WIRE to be used as different wire types may have different strand sizes and number of strands and differing resistance per unit of length. Longer length wire in a home made link will result in longer opening time due to higher resistance and more amps flowing causing damage In adfition, termination methods will also effect performance. Commercially available fuses, (a maxi fuse or a mega fuse) have predictable opening or interrupting times. IMO...Commercially available fuses will afford the degree of protection desired......just my opinion of course
BOB RENTON

 

[70ChargerRT]

So Dakota Digital gauges does away with the ammeter. I tied those 2 ammeter wires together.

 

[RJRENTON]

So Dakota Digital gauges does away with the ammeter. I tied those 2 ammeter wires together.

OK....just make sure that the connection is adequately insulated from ground....
BOB RENTON

 

[70ChargerRT]

I’m not sure if

I have FI, 3 amps, and the rest factory accessories, a/c etc... 135 amp alternator. I used to have 2 e-fans also. I melted my fusible link due to amperage "draw". I could have redone all the wiring to starter relay w higher gauge and larger fusible link, but for me the easiest route was go directly from alternator to battery, large 2ga cable. Then a post for amps, FI and e-fans to wire directly for their "hot" feed relays. Then the stock cable from battery that splits for starter and starter relay. This way there is no "thru" power draw at relay except for the factory accessories. No issues since

Did you have a 1 wire alt or external Voltage Regulator? A lot of people don’t know on a 3 wire external if you don’t have an ungraded regulator to match the alternator it will also cause the problem you had. I’ve got a 3 wire. My sniper was flashing yellow on the volts only charging at 12.4 and 12.5 so it had a hard draw when the fans were own. I called tuff stuff and the guy I talked to was very Mopar knowledgeable. I didn’t have a clue about the upgraded voltage regulator. He also told me to run a 4 gauge wire from
The alt to the battery post and the. Ground the alternator itself. Problem solved and fixed but now me accidentally melting my fusible link has opened another can of worms

 

[BigFlo]

Yes, I fully agree with you, and I didn't specifically state that.

But in a way, that's like saying you don't need to upgrade your transmission if you put a 700 HP engine in the car and never put your foot to the floor! Invariably someone will put a high power radio in the car (or already did), upgrade the headlights or put other items that put a significant additional load on the system. It is likely why they upgraded the alternator!

Regardless, I think we agree that the electrical system needs to be sized and protected based on the potential load it will be carrying.

We are in total agreement. I interpreted your post differently than you intended.

 

[70ChargerRT]

I am thinking that fuse link was on its way out already and it was just time. The starter positive wire being off should have done nothing. The fuse link should never be larger with stock cab wiring. Maybe you have the stock black wire hooked up at the alternator, along with your bypass wire and got a back feed, unlikely, or somehow you have a high draw accessory on that line, or it grounded while it was unhooked, only way I can see that happening.

I only have like a 1000 miles on this harness. After I tried to crank it a couple times there was smoke came out from the car around where the starter relay was at. First thing I noticed was the fusible link was melted open about an inch and it was super hot. All I know it happened when the starter cable was unhooked, maybe it ground out???

 

[4406bbl]

It almost had to have grounded to do that. One other way is a backfeed from battery thru your 4 gauge wire into the 10 gauge black wire at the alternator, if the black is still hooked up. The 4 gauge should also have fuse link, or a large fuse for protection, in the event of a wreck, battery short, or alternator short.