Battery Cable Sizing

[85lebaront2]

...the crimper...

Solder is MUCH better than crimping in this application, for several reasons.

Or what is your numerical value of 'much smaller'?

I don't remember, but it's in the 1st diagram I posted above. SMN is down for maintenance at the moment...

My plan for the aux battery is to run my amp, sub, fog lights and eventually a run to the rear bumper for my trailer winch.

With those goals, the positive between the main and aux would just be for charging from the alt.

Not if you use ANY of those while the engine is running (alt. working). In that case, the current to those loads could be expected to come from the aux.batt., the main batt., the alt., or any combination at any moment. So the connecting wires between those 3 voltage sources should be sized for the peak load (probably the winch).

I assume the factory yellow wire would be enough for that?

Only if you NEVER use a load larger than that Yellow wire can handle while the engine is running.

Now lets say if I wanted to use the 'jumper' mode of the isolator. In that case I would need larger?

Yes, if you ever expect to pull substantial current INTO the aux.batt. or the circuits connected to it.

Steve 83 - "Solder is MUCH better than crimping in this application, for several reasons."

If that is the case, then why don't the factories use soldered connections?

If you really want to see something interesting, un-wrap and remove all the goo from a Detroit factory multi-wire splice, it's welded.

[kramttocs]

Steve 83 - "Solder is MUCH better than crimping in this application, for several reasons."

If that is the case, then why don't the factories use soldered connections?

If you really want to see something interesting, un-wrap and remove all the goo from a Detroit factory multi-wire splice, it's welded.

If I want to add a 1/0 or 1 between the junction block or relay and the main battery, I can keep the factory hot yellow connected right?

The higher draw will take the larger cable, correct?

[Steve83]

...why don't the factories use soldered connections?

Because it's more expensive & difficult for mass-production than just melting the Lead into the battery cables. But that's not as safe or practical for one person working on one vehicle as solder.

If I want to add a 1/0 or 1 between the junction block or relay and the main battery, I can keep the factory hot yellow connected right?

Yes, as long as you make good splices, and NEVER disconnect the big one (even accidentally, as by a poor connection failing) while there's a heavy load on the aux.batt.

The higher draw will take the larger cable, correct?

Not exactly; current will flow through both, based on the total resistance along each path between the points where you splice your new cable in.

[ArdWrknTrk]

If I want to add a 1/0 or 1 between the junction block or relay and the main battery, I can keep the factory hot yellow connected right?

The higher draw will take the larger cable, correct?

As the smaller wire -or cable- in parallel gets saturated (there are only so many free electrons to move) a greater percentage of current (amps) will be carried by the larger cable.

The yellow will be fine.

To Steve's statement.

I think Bill is referring specifically to harness splices wrapped in tape.

The older lead battery terminal lugs were done that way because battery cables are somewhat universal, and it's cheap, fast and easy to do that way in a production environment.

Harness splices are welded (fusion of the copper) because A) welding is stronger than solder. B) carries current better. C) there is no boundary for corrosion to get started.

[Danny G]

My plan for the aux battery is to run my amp, sub, fog lights and eventually a run to the rear bumper for my trailer winch.

This is something I do not understand, this isn't the first time I have seen this. If your batter is set up where the main and spare battery share a positive and negative connection that battery is wired directly in parallel and at that point it makes no difference where you tap to power what.

What I would do is just tap off whatever location is convenient at that time and buy an appropriately sized fuse block, then use said fuse block to power whatever.

Looking at the diagrams below you can see that there is functionally no difference between these two methods, except putting in a fuse box is a cleaner install and will allow easier wiring and troubleshooting. Better to do the latter than have half a dozen wires hanging off the battery positive post.

Using the AUX battery

Using a fuse block

I have a lot of professional experience (16 years and 8 days) with wiring being put through the most abusive circumstances known to man. When done correctly a crimp is far superior to a solder joint. In my experience solder joints break over time with vibration and other outside forces. This is why outside of circuit boards solder joints are only used for shield splicing in aviation.

[ArdWrknTrk]

My plan for the aux battery is to run my amp, sub, fog lights and eventually a run to the rear bumper for my trailer winch.

This is something I do not understand, this isn't the first time I have seen this. If your batter is set up where the main and spare battery share a positive and negative connection that battery is wired directly in parallel and at that point it makes no difference where you tap to power what.

What I would do is just tap off whatever location is convenient at that time and buy an appropriately sized fuse block, then use said fuse block to power whatever.

Looking at the diagrams below you can see that there is functionally no difference between these two methods, except putting in a fuse box is a cleaner install and will allow easier wiring and troubleshooting. Better to do the latter than have half a dozen wires hanging off the battery positive post.

Using the AUX battery

Using a fuse block

I have a lot of professional experience (16 years and 8 days) with wiring being put through the most abusive circumstances known to man. When done correctly a crimp is far superior to a solder joint. In my experience solder joints break over time with vibration and other outside forces. This is why outside of circuit boards solder joints are only used for shield splicing in aviation.

I'm interested in what you do for a living.

Electrician on oil rigs?

Mining?

What are the most abusive conditions known to man?

[Danny G]

I'm interested in what you do for a living.

Electrician on oil rigs?

Mining?

What are the most abusive conditions known to man?

I have worked in aviation/aerospace both military and for a major company in the industry.

The wiring on those products goes through more vibration, intrinsic and extrinsic heat, rapid environmental changes, lightning strikes, corrosive fluid exposure (hydraulic, fuel, oil, coolants), and physical stress from flexing than any automotive or typical ground install. Sometimes all of the above at the same time, and they do it with crimps across the board. Splices, pins/contacts, shield terminations are all crimped in place.

We had a handful of soldered connections on the Harriers I worked on as a dual MOS 6312/6332 that would consistently fail, especially on antenna to the rear of the aircraft. Seen the same thing on helo's.

On the more modern examples of aerospace, pretty much outside of the printed circuit boards, solder has gone the way of the dodo. Hell the wires going to the power panels from the generators and engines are all copalum splices and crimps made with a hydraulic crimper that puts out a few thousand PSI. Actually I think pretty much every 1/0, 2/0, 3/0 cable is done in that manner. Smaller cables use smaller crimpers, and larger ones (10 gauge and up) use hand held hydraulic/ratchet type or powered hydraulic/ratchet type luggers. We call the hand held ones knuckle busters because when the crimp is finished the tension on the handles releases while your hulking out on it and you slam your knuckles together.

[kramttocs]

As the smaller wire -or cable- in parallel gets saturated (there are only so many free electrons to move) a greater percentage of current (amps) will be carried by the larger cable.

The yellow will be fine.

Thanks!

[kramttocs]

My plan for the aux battery is to run my amp, sub, fog lights and eventually a run to the rear bumper for my trailer winch.

This is something I do not understand, this isn't the first time I have seen this. If your batter is set up where the main and spare battery share a positive and negative connection that battery is wired directly in parallel and at that point it makes no difference where you tap to power what.

It's the isolator that makes the difference in the diagrams and the reasoning. It allows the aux battery to be used without draining the main.

[Gary Lewis]

This is something I do not understand, this isn't the first time I have seen this. If your batter is set up where the main and spare battery share a positive and negative connection that battery is wired directly in parallel and at that point it makes no difference where you tap to power what.

The factory aux battery setup used a relay to parallel the batteries as soon as the key was turned on. I think Scott is going to use a relay with electronics that senses battery voltages and won't parallel the two until one or the other gets to a preset value, showing it is getting charged.

So my guess is that he wants the sound system on the aux battery so he can drain it w/o fear of not being able to start the truck. Which is why I put the winch on the aux battery on Big Blue.

As for the yellow wire, so far the factory wire has held on Big Blue. But I've never done much winching w/o the truck running and therefor both batteries have been in parallel. And I'm still running the 1G. My worry about that wire is when the alternator has been replaced by a 3G and when the aux battery has been depleted and that big alternator kicks out twice what the original 1G was capable of.