Relocated Battery Wiring

[ARCTICFRONTIER]

Here is my plan for how to wire it.

From the battery, I’ll connect to a 135 amp circuit breaker with 1/0 gauge wire rated for 150 amps. This would give me some protection to the wire running from the bed to the engine and ensure I don’t exceed its capacity. Then continue with 1/0 to the engine compartment. I’d connect the 1/0 wire to a battery terminal stud mount rated for 250 amps. From this mount I would connect the existing wires (all 1/0 gauge already) that connect to my battery now (starter, alternator, fuse panel and stereo amp).

I have a 100 amp alternator, my amp is max 400 watts and no AC. I do run a FAST EFI system with an electric pump.

I’ve upgraded the grounds using 1/0 wire to the chassis and to the engine block. I’d add another ground to the frame from the battery once it’s in the bed.

Does this sound okay? Any thing you would change?

[dmjlambert]

Normally some of the 12 gauge wiring going into the cab is unfused. At the points where you attach your 1/0 wire to the 12 gauge wiring, I would insert 6 to 9 inches of 16 gauge fusible link wire, to protect your 12 gauge wire. Fusible links are 2 wire sizes smaller (that is 4 gauge numbers higher) than the wire it's protecting.

[MikeB]

Originally Posted by dmjlambert

Normally some of the 12 gauge wiring going into the cab is unfused. At the points where you attach your 1/0 wire to the 12 gauge wiring, I would insert 6 to 9 inches of 16 gauge fusible link wire, to protect your 12 gauge wire. Fusible links are 2 wire sizes smaller (that is 4 gauge numbers higher) than the wire it's protecting.

Either that or another fuse. My old square body used the setup below that was part of a universal kit from American Autowire. Connection to the starter BAT terminal is on left side of the fuse. (The starter BAT terminal is connected to the battery.) Connections to fuse panel and alternator are on right side of the fuse.

The kit uses 6 gauge wire and 175 amp fuses, but I used 8 gauge SXL wire and one maxi-fuse (100 AMP, I think) because the truck had a low amperage draw and 78-amp alternator. Not to mention the 6 gauge wire was a bear to route! The kit also includes a second fuse and fuse block that snaps on to the first one.

Also, my connection to the fuse panel actually goes to a firewall-mounted stud first where the alternator sense wire is connected. that means the alternator tries to keep 14.2 volts at that point.

[ARCTICFRONTIER]

Thanks for the help guys. Adding another fuse seems like a good idea. Looks like I have a bit more planning to do.

Originally Posted by MikeB

Either that or another fuse. My old square body used the setup below that was part of a universal kit from American Autowire. Connection to the starter BAT terminal is on left side of the fuse. (The starter BAT terminal is connected to the battery.) Connections to fuse panel and alternator are on right side of the fuse.

The kit uses 6 gauge wire and 175 amp fuses, but I used 8 gauge SXL wire and one maxi-fuse (100 AMP, I think) because the truck had a low amperage draw and 78-amp alternator. Not to mention the 6 gauge wire was a bear to route! The kit also includes a second fuse and fuse block that snaps on to the first one.

Also, my connection to the fuse panel actually goes to a firewall-mounted stud first where the alternator sense wire is connected. that means the alternator tries to keep 14.2 volts at that point.

[cj847]

I think a V8 starter can pull up to 250 amps or so. I think you need a bigger circuit breaker or none at all.

[MikeB]

Originally Posted by cj847

I think a V8 starter can pull up to 250 amps or so. I think you need a bigger circuit breaker or none at all.

I think AAW, Ron Francis, et al would tell you that no fuse or breaker should be used between battery and starter.

[HotWheelsFan]

Think of a fuse or circuit breaker as a fail-safe not to burn down your vehicle in case of an accident that may pinch a positive wire and ground rather than protecting your wiring.

And remember, too high of an amp rating for a short circuited wiring problem will burn the wiring at the area of lowest amp rating of wiring.

[LS short box]

Most cars and trucks don't have a fuse or circuit breaker in the heavy gauge wire from the battery to the starter. Secure the battery to starter heavy gauge wire really well along the frame rail and I think you will be fine.
I used a Painless kit a few times and there is a maxi fuse that protects the rest of the vehicle.

[indymachinist]

Think about how many cranking amps does your battery have?

[HO455]

I have owned several cars with trunk mounted batteries from the factory. None of them had a fuse or other kind of over current protection in the supply wiring to the starter motor. They were carefully engineered wire runs so the starter supply did not have any opportunity to short out. Either from vibration or heat.


A 350 Chevrolet will draw between 250 and 350 amps when starting. The wide range depends on compression, ignition timing and the actual mechanical condition of the engine and the starter.


This link may help.

https://www.motortrend.com/how-to/be...anking%20power.

[MikeB]

Originally Posted by HO455

A 30% drop in voltage means a 30% increase in amperage. I.E. your battery voltage dropped to 8 volts.

That's incorrect because the starter's resistance (R) is a constant. (The exception being it will vary somewhat with temperature.)

I=E/R

So if voltage (E) deceases, current (I) decreases.

[HO455]

You are correct.
What I was thinking was in order to do the same amount of work at a lower voltage the motor would have to draw more amperage.
I will edit the post.
And I apologize for any confusion I may have caused.

[MikeB]

You may have been thinking less voltage = more current with something like an electric motor. I once had an air compressor wired for 120 volts that would occasionally trip a breaker.

It was a dual voltage motor so I was able to rewire it for 220/240 volts. It then drew approximately half the current to do the same work, and never tripped a breaker again.