Resolved 2G Alternator Wiring Question Inside

[alice]

I will be relocating my battery to the trunk in my 2g and just have a quick question on my Alternator wiring plans. I am running the 96amp Alternator from the Galant and will be running the alternator wires from the fusebox through a 4ga wire directly to the battery. In that line, I plan on having both a 140amp Circuit Breaker and an inline fuse in addition to the stock Alternator fuse which I use a 100amp fuse for. My question is, should I use another 100amp fuse in the Alternator line or should I go larger ie: 125amp or even 140amp?

 

[delta448]

The lowest amperage fuse or breaker that is in the line will be the only effective one. The only reason to use more than one in this case would be to prevent battery discharge in the event that there is damage to the line between the fuse box and remote battery or the line from the alternator to the fuse box. Ideally, the two fuses would be placed as close to the battery and alternator outputs as possible.

Most alternators have an average output of less than 65% of their rated amperage. If I were you, I'd just use a single 100-110A breaker on the line right at the battery.

 

[alice]

Awesome man! Thank you for the educated reply indeed. So, if I leave the stock 100a Alternator fuse and drop the additional inline fuse and add a Circuit breaker close to the battery, that would work just fine?

Lastly, on my main battery line, I will have only the fusebox, starter, fans, and gauges powered from the line. Will just a 140a cb be enough? And a distribution block of course. No fuses in the main to distribution block line at all.

 

[delta448]

So, if I leave the stock 100a Alternator fuse and drop the additional inline fuse and add a Circuit breaker close to the battery, that would work just fine?

Yep.

Lastly, on my main battery line, I will have only the fusebox, starter, fans, and gauges powered from the line. Will just a 140a cb be enough? And a distribution block of course. No fuses in the main to distribution block line at all.

I'm not sure off the top of my head. You just need to add together all the amperages for every device on the feed and allow for about 5-10% over that value. Also, keep in mind that if you have a non-stock shortblock, the starter may demand more power to crank the engine.

 

[alice]

I found that my fans pull 7amps a piece. I'm not sure on the accuracy of that but its as close to a real number as I can get. I also have 3 gauges powered from the battery, the fusebox with everything minus ac, abs, and cruise, and stock 2g starter. Any rough estimates on how many amperes that would be all together?

 

[wrencher]

One fuse placed in the proper place is sufficient enough to protect the circuit.
Adding any extra fuses just serves to add resistance to the circuit through all the extra connections & componets. All be it a slight increase but a charging circuit is not where you want any increased resistance if you can help it.

7 amps for a cooloing fan is pretty low. They vary as to what they pull by they're design.
But approximately 15-25 amps (high speed) is about every fan out there pulls each.
It takes another 8-15 amps just to run the car. Pump, coils , injectors ETC.
All these numbers vary so much between different vehicles.

For the battery relocation, are you running one positive cable back to the engine bay?

 

[alice]

There will be one 0/1 gauge wire as the main going from the battery to the distribution block in the engine bay. From that distribution block I will be powering everything in the fusebox, my 3 prosport gauges, 2 fans, and the starter. The alternator line will be completely separate from the main line and run from the fusebox directly to the battery terminal utilizing just the stock fuse in the fusebox and one inline 140amp circuit breaker at the battery.

Right now, I have all of the above plus the alternator all traveling through my one 0/1 gauge main line and I am having charging issues and generally do not feel like its safe as there is no fuse in the main line at all from the battery to distribution block. The new main line will have one 140amp circuit breaker inline between the battery and distribution block in the bay.

 

[wrencher]

Rule of thumb most starters can draw 140 amps on a 4 cylinder.
It's (very) roughly 150/175/200 for a 4/6/8 cylinder.

So a circuit breaker might not be a great idea to put in there.
You could wire in a battery disconnect too, that might be a good option if you dont want the cable run to be powered.

As for charging issues I would look @ voltage drops between the battery & the output lug of the alternator. Then alternator case to battery, both tested while charging. ( + to + & - to -)

 

[alice]

Rule of thumb most starters can draw 140 amps on a 4 cylinder.
It's (very) roughly 150/175/200 for a 4/6/8 cylinder.

So a circuit breaker might not be a great idea to put in there.
You could wire in a battery disconnect too, that might be a good option if you dont want the cable run to be powered.

As for charging issues I would look @ voltage drops between the battery & the output lug of the alternator. Then alternator case to battery, both tested while charging. ( + to + & - to -)

Thanks for the great info! I figure I have to have some sort of circuit protection on the main line so I may toss just a 200amp cb in there and call it a day. My main line is essentially the same as the famous turbosax2 style.

I'm thinking of adding a few ground from engine to chassis and Alternator to chassis or block.

 

[wrencher]

Just keep in mind what a circuit breaker is.
They're designs differ slightly , but it's basically a bi-metallic switch.
They heat up the bi-metallic portion of the circuit breaker from excessive amperage flow & that opens the circuit.

So theres 2 problems they can produce in your situation.
If there where to be a dead short, the circuit breaker could keep resetting & sending power to the short.
Then because of the bimetallic design of the compent, it's possible to get it fatigued through heat cycling.
Starting the car say draws 160 amps. That heat will go through the circuit breaker, it is possible with time to degrade the breaker down to less of an amp rating.
With enough time it could be tripped on start up. It usually depends on the quality of the componet to start with. But they can & do degrade at varing rates.
Just keep those things in mind.

 

[alice]

Just keep in mind what a circuit breaker is.
They're designs differ slightly , but it's basically a bi-metallic switch.
They heat up the bi-metallic portion of the circuit breaker from excessive amperage flow & that opens the circuit.

So theres 2 problems they can produce in your situation.
If there where to be a dead short, the circuit breaker could keep resetting & sending power to the short.
Then because of the bimetallic design of the compent, it's possible to get it fatigued through heat cycling.
Starting the car say draws 160 amps. That heat will go through the circuit breaker, it is possible with time to degrade the breaker down to less of an amp rating.
With enough time it could be tripped on start up. It usually depends on the quality of the componet to start with. But they can & do degrade at varing rates.
Just keep those things in mind.

Knowing that circuit breakers degrade over time, would there be any safe way of running my main line and my alternator line without circuit breakers?

I did end up wiring a 200amp fuse in my alternator to battery line and left the stock alternator fuse as well. I figure the higher amp the fuse, the less resistance there will be considering resistance is an enemy in a charging circuit. I'm basically following the turbosax2 relocation minus the use of the 200amp Saturn alternator. I appreciate all of your knowledge Wrencher!!

Also, I made a mounting bracket for both circuit breakers out of stainless steel and plan to mount them to it. Is that going to cause an issue of any sort? Or should I coat the bracket with something?

 

[wrencher]

For a mount? or connection wasn't sure you meant there?
Stainless is kind of low on the list for conductive materials.
It can work, but copper or aluminum a lesser choice is a better conductor than SS.
for a mount I would use fiberglass base or polycarbonate. A 200 ampere fuse with bolt on studded terminals shouldn't be hard to find?
I would rather isolate the componet best as possible & not use metal @ all.
I would be careful with the fuse too & have a spare on hand.

If you put the 200 amp'r back by the battery it will just serve to protect up to the fuse block.
The stock 120 will protect the rest of the circuit.
Would a battery cut off switch ala-race car not be an option?
You can unpower the car when not in use?

Usually it's not the fuse/circuit breaker itself that add resistance to a circuit.
It's the connections.
Where talking small miniscule amounts here though.
But under a load the higher the amperage the greater the effect.
Like I said in a charging circuit it can effect it somewhat.

Electrical stuff can be easy. Just remember ohms law.
Google it but an automotive example;
Say a engine starting= 10.4 volts battery voltage WHILE cranking.
Resistance of battery cable run to starter .006 ohms. (this assumes ground is .00 ohms)
10.4 ÷ .006= 173.333 amps.
There are mechanical variables that effect the end users amperage draw but it gets you in the ballpark, + lets you know the circuit is correct.
Change the resistance & see what happens. Same with voltage to a lesser degree to a point.


No big deal on the help, just the stuff 25 years in the field drives into your head.

 

[alice]

I have my OEM 96-98 Galant alternator on my 2g wired stock to the fusebox through the stock alternator fuse then to a 200amp ANL fuse to 4ga wire to 140amp circuit breaker then to the battery which is in the trunk. Tonight, while out on a cruise, I started tripping the circuit breaker every few minutes obviously cutting power to the battery and its got me thinking.....If I'm tripping the 140amp circuit breaker and not blowing the stock 100amp alternator fuse, wouldn't this suggest that the circuit breaker is a faulty unit because its tripping before the fuse is blowing?

I believe the Galant alternator is like 96amps or something like that so why would I be popping the CB first and not the fuse?

 

[wrencher]

The circuit breaker is a thermal bi-metallic switch.
It can be stressed & reduce it's rating.
Thermal cycling of a breaker degrades it.

That comes to how this breaker is installed.
Out of the stock underhood box, you have a fuse & then the breaker?
The starter wired of this circuit as well?
Trying to picture how many connections you have in this circuit @ the fuse box.

Connections plus the run of 4 gauge to the trunk will create resistance.
Resistance even in tiny amounts is a load to a circuit.
The connections are real important here due to the nature or this circuit.
That can heat the breaker, stressing it constantly causing it to trip.
Then as it keeps heating & tripping it will degrade it's capability.


There are some other issues using circuit breakers, they have to be matched to the circuit to operated properly.
Not just the installation/connections are important.

The circuit breaker rating that matches the wire size the breaker is trying to protect. If the wire size is too small or too big for the breaker, the heat sink characteristics of the wire will shift the calibration curve of the breaker up or down, respectively.

If the wire is too big, the breaker will respond more slowly to a current overload, thus inadequately protecting the wire.
If the wire is too small, the breaker will open earlier than designed, potentially causing electrical system malfunctions.

 

[alice]

Here's a semi visual of how my alternator setup goes:

[Alternator (4 White Wires)]-->[Fusebox through stock 100AMP fuse]-->[white wires that originally connected directly to the battery]-->[200AMP ANL Fuse]-->4ga wire to the trunk to [140AMP Circuit Breaker]-->4ga wire to battery

So, I am tripping the 140 AMP circuit breaker which is about 12" from the battery but not blowing the 100AMP fuse in the fuse box. Wouldn't this suggest that either the circuit breaker is faulty or there is a flaw in the alternator system in general?

 

[wrencher]

So you have the starter wired in where in there?
If the 4 ga is feeding the starter, a 140 CB is gonna get stressed.
That & IMO way too small for 12-14 foot run of cable for 140 amps.
Which the starter will likely draw more amperage than that & with those numbers your well over a half a volt in voltage drop using it for the starter.

12 foot 4ga approx 10 volts cranking 140 amp load= .83 voltage drop. Too high...
And like I said the amperage is likely higher than that which makes the volt drop much worse.
All the exact numbers are highly subjective per vehicle, but 4 gauge being a constant it never comes out good.
I would put another 200 amp fuse in there @ the battery to replace the CB at the least.