CS144 + BIG 3 upgrade added wiring Clarification

[infamousRNR]

dudes,

question - when running the a new larger gauge (2GA) wire with a 160A fuse IN-LINE with the stock factory wiring still attached, what's stopping the current from the higher output alternator from choosing the path of the factory wiring vs the new larger gauge wiring????





the concern here is blowing the factory fuse that is 120A..

because the CS144 outputs ~140 amps vs the stock alternator at ~80/90 amps, we don't understand how the factory fuse won't blow.

the electrical circuit will take the path of least resistance but because the factory wiring will still be attached and run in series with the new wiring, we are looking for a sound explanation as to WHY adding this higher output alternator with thicker gauge wire won't run the path of the stock wiring instead and eventually blow the 120A fuse in the factory fuse box.....


from our research, it sounds like many people have run their factory wiring in-line with the new wiring they installed with the big 3 AND the CS144 alternator without issues of blowing that fuse.... but really curious as to WHY the current will not blow this fuse.





[MENTION=10169]TheDurk[/MENTION]
[MENTION=59542]Singtoe[/MENTION]
[MENTION=75316]jgue467[/MENTION]
[MENTION=106775]The Engineer[/MENTION]



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[phattyduck]

dudes,

question - when running the a new larger gauge (2GA) wire with a 160A fuse IN-LINE with the stock factory wiring still attached, what's stopping the current from the higher output alternator from choosing the path of the factory wiring vs the new larger gauge wiring????
.

By in-line with, do you mean parallel? Like, added right next to the factory wire? In-line would normally mean added length, which doesn't make sense with any of the big-3 type wiring upgrades. Generally you replace or add in parallel to the factory wiring.

If so, it would choose the path of least resistance, like you said - which is the bigger wire and higher amp fuse. Some current would likely still pass through the factory wiring, but it will be greatly reduced by the current flowing through the new alternate path.

-Charlie

 

[infamousRNR]

By in-line with, do you mean parallel? Like, added right next to the factory wire? In-line would normally mean added length, which doesn't make sense with any of the big-3 type wiring upgrades. Generally you replace or add in parallel to the factory wiring.

If so, it would choose the path of least resistance, like you said - which is the bigger wire and higher amp fuse. Some current would likely still pass through the factory wiring, but it will be greatly reduced by the current flowing through the new alternate path.

-Charlie

thanks for the quick response Charlie! appreciate you and also the fact that you're always here and still super active on this forum....


to clarify - we would be ADDING in parallel to the factory wiring.


so factory wiring stays in place and is still connected in addition to ADDING new, larger gauge wire (2GA with 150AMP fuse)





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[19963.4lsr5]

If they are truly parallel paths each will share half the load. It doesn’t matter what the wire gauge is.

I’d run the new Alt strait to the battery with the 160a fuse or fuseable link in series and leave the factory wire between the battery and the j-box the same. With the 120a factory fuse.

No parallel wires. Pull the old alt charge wire from the j-box and run it strait to the battery.

There will be 160a fuse between the Alt and the battery and a 120a fuse between the battery and the J-box.

Just my opinion…..


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[phattyduck]

so factory wiring stays in place and is still connected in addition to ADDING new, larger gauge wire (2GA with 150AMP fuse)

In that case, my comment above stands.

Resistance in metals goes up as they heat up - in the case of the fuse, this is what causes the runaway reaction when they have too much current flowing through them (gets a little warm, resistance goes up, gets warmer, higher resistance, heats up more, then pop!). If there are two parallel paths, this action would 'even out' the current that flows through the two optional paths, and would give you approximately the fuse rating of the two fuses combined. Since the fuses are there to stop the wire from catching fire (not from damaging the alternator), that setup should be reasonably safe.

-Charlie

 

[phattyduck]

If they are truly parallel paths each will share half the load. It doesn’t matter what the wire gauge is.

Not really true... Both fuses and wires have inherent resistance that will cause the current load to be shared inversely proportional to the resistance in the two optional paths. Larger diameter wires and larger amp fuses both have lower resistance than smaller wires/fuses would have.

I would agree that the best setup would be to remove the factory charge wire and replace it with a single wire, but that is just as much to clean things up as it is for safety, etc. An undersized wire/fuse that blows if the main (high current) connection fails for some reason doesn't add any reliability, only weight and complexity.

-Charlie

 

[19963.4lsr5]

Not really true... Both fuses and wires have inherent resistance that will cause the current load to be shared inversely proportional to the resistance in the two optional paths. Larger diameter wires and larger amp fuses both have lower resistance than smaller wires/fuses would have.

I would agree that the best setup would be to remove the factory charge wire and replace it with a single wire, but that is just as much to clean things up as it is for safety, etc. An undersized wire/fuse that blows if the main (high current) connection fails for some reason doesn't add any reliability, only weight and complexity.

-Charlie

I don’t want to start anything bad but,……

Have you actually put a clamp on amp meter between your two charge wires and recorded the difference?

Have you took a 3ft section of 2awg wire and compared its resistance to a 3ft section of 6awg? The readings will be Nill in ohms law. Heat is the only thing that will change its resistance.

Number 6 wire 4ft long is rated around 150a. DC. Remember it’s the watts. Putting a 2awg wire on the Alt is awesome. But, it doesn’t need to parallel the OEM harness to be effective.

Patty I most humbly respect everything you post but the watt rating of a wire gauge at 12vdc compared to 120vac (which is most of the charts google will link you too) are not the same.

If one is putting a 2awg wire on the Alt. Running it strait to the battery is not comprising the charging system in the least. And easy peezy. A 4ft section of 6awg wire is more than capable of handling a CS 144 Alt. Paralleling a 2awg with the factory harness is more than enough.

I rarely toot my own horn but this discussion is my life. It’s my job and not a hobby.

Gene


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[infamousRNR]

I donÂ’t want to start anything bad but,Â…Â…

Have you actually put a clamp on amp meter between your two charge wires and recorded the difference?

Have you took a 3ft section of 2awg wire and compared its resistance to a 3ft section of 6awg? The readings will be Nill in ohms law. Heat is the only thing that will change its resistance.

Number 6 wire 4ft long is rated around 150a. DC. Remember itÂ’s the watts. Putting a 2awg wire on the Alt is awesome. But, it doesnÂ’t need to parallel the OEM harness to be effective.

Patty I most humbly respect everything you post but the watt rating of a wire gauge at 12vdc compared to 120vac (which is most of the charts google will link you too) are not the same.

If one is putting a 2awg wire on the Alt. Running it strait to the battery is not comprising the charging system in the least. And easy peezy. A 4ft section of 6awg wire is more than capable of handling a CS 144 Alt. Paralleling a 2awg with the factory harness is more than enough.

I rarely toot my own horn but this discussion is my life. ItÂ’s my job and not a hobby.

Gene


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debate is good and it's healthy - but just to clarify, what physically happens when you run 2 separate gauge wires, each with their own fuse rating, and add a higher output alternator?

does the power take the path of least resistance and primary go through the larger gauge wire, or share current between 2 wires making your flow "safer"/ not sure adding more wires to the same connection makes things better out worse. it sounds like 1 connection is better but there is work involved with removing the factory connection... or is it just as simple as removing the fuse from the factory fuse box?


it is my naive understanding that the factory dash cluster may need voltages from the factory fuse both to avoid a BATTERY LIGHT on the dash cluster? would eliminating the factory alternator circuit mess with this?

 

[gamefreakgc]

opcorn:

I have a high output alternator and big 3 wiring, I'll let you know if it explodes.

 

[JZiggy]

Charlie and Gene are both on track I think. Charlie’s just reminding us of how parallel circuit math works which is correct. I realized too that the actual resistance of both paths, as Gene is saying, is negligible so it is probably indeed the case that both would share an equal current load... until or if they heat up, then the difference between a 6 and 2 ga will become apparent.

I’ll add that with such heavy wiring any wiring resistance will be overshadowed by resistance from dirty or loose contacts, etc.

 

[JZiggy]

Also — should the fuse be a fast or slow blow type?

 

[19963.4lsr5]

Also — should the fuse be a fast or slow blow type?

I like the slow blow / time delay.

I need to draw it out to see it on paper to verify the fuses are indeed in parallel. I think the Alt pushes across the J-Box fuse to feed the battery. However, having a 160a fuse in parallel with a 120a fuse means neither fuse will respond properly to a short to protect the wiring.

And yes I think any difference in amps between the two parallel charge wires would be simple connection resistance.

I’ll admit I installed the Hall Effect Amp gauge in my rig to test my Alt output with smaller pulleys. But it’s now Permanent. I’ll buy another to put in my toolbox for troubleshooting.


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[phattyduck]

I don’t want to start anything bad but,……

Have you actually put a clamp on amp meter between your two charge wires and recorded the difference?

Have you took a 3ft section of 2awg wire and compared its resistance to a 3ft section of 6awg? The readings will be Nill in ohms law. Heat is the only thing that will change its resistance.

Number 6 wire 4ft long is rated around 150a. DC. Remember it’s the watts. Putting a 2awg wire on the Alt is awesome. But, it doesn’t need to parallel the OEM harness to be effective.

Patty I most humbly respect everything you post but the watt rating of a wire gauge at 12vdc compared to 120vac (which is most of the charts google will link you too) are not the same.

If one is putting a 2awg wire on the Alt. Running it strait to the battery is not comprising the charging system in the least. And easy peezy. A 4ft section of 6awg wire is more than capable of handling a CS 144 Alt. Paralleling a 2awg with the factory harness is more than enough.

I rarely toot my own horn but this discussion is my life. It’s my job and not a hobby.

Gene

First, to be clear, we are in agreement about the connections and capabilities of the wire / fuses / sizes. I'm an electrical engineer, though I design consumer products, not power electronics.

My only point here is that there will be unequal sharing of load current if there are two parallel wires of different sizes with different fuse ratings. Ohms law is Ohms law, whether or not we are talking about ohms or micro-ohms.

I'm looking forward to doing the big-3 (or something similar) on my truck soon - I just had some battery terminal issues recently and it is time for some upgrades/fixes there...

-Charlie

 

[19963.4lsr5]

First, to be clear, we are in agreement about the connections and capabilities of the wire / fuses / sizes. I'm an electrical engineer, though I design consumer products, not power electronics.

My only point here is that there will be unequal sharing of load current if there are two parallel wires of different sizes with different fuse ratings. Ohms law is Ohms law, whether or not we are talking about ohms or micro-ohms.

I'm looking forward to doing the big-3 (or something similar) on my truck soon - I just had some battery terminal issues recently and it is time for some upgrades/fixes there...

-Charlie

To me there isn’t going to be a huge difference between the factory wiring current and the upgraded wiring in parallel current.

Without having hard numbers simulating this the unequal sharing of load between a 6awg and a 2awg DC parallel circuit less than 4ft in length will be more in the connection resistance than the ability of the conductors based on gauge diameter.

I feel like clamping a leg of my jumper cable to parallel the Alt output to the battery and putting my Fluke DC clamp on amp meter on the wires to measure the difference……….

I’m a great Arm Chair Technician in my own mind though. [emoji16]


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