Here is what a properly crimped lug looks like... its a cold weld.

Solder does nothing for you except create more work and problems.

Found the temco and the corresponding lugs.

Is that a TH-F6A I see peeking out of the box? Very nice choice.

@Bumbo

This is what I ended up with. I've been leaving the circuit breaker open until someone better versed in electrical work, such as yourself, looks over what I've built.

@trailtruck

At a glance it looks good... nice work

I would loom the positive cable, at least between the fuse and battery, for additional abrasion resistance/protection.

I think 3/8 is the correct size for 4 AWG... but dont quote me on it.
https://www.amazon.com/Burnstine-T-3...2F8+split+loom

Did you go with all the sizes in the thread like 4 AWG, 125A fuse, 100 breaker?

Aside from that, just make sure your ground connections are good, and the terminals/lugs are tightened down with an appropriate torque...

Is ground going to battery neg or to something else like the engine bay walls?

Also, this isn't necessary, but you can always get a paint pen and index / witness mark all your final connections. This way you can visually see if anything has moved or un-tightened over time without having to put a tool on it. Note the orange marks on the terminal/screws...

Example:

@Bumbo Yep. 4AWG wire with 2 different hole size cable lugs depending on the diameter of the stud they're going on to make sure the fit is correct. I used the double wall adhesive-lined heat shrink tubing and 125A main fuse and 100A breaker.

I'll loom that wire. Otherwise, I've been running breaker-open most of the time due to fire concerns before I had someone qualified like yourself look at it. Am I good to go to run it hot all the time?

Also, how much waterproofing do I need to do to it as far as rain or river crossings are concerned? I won't be submerging up to the headlights or anything crazy like that but it still remains a question mark. Thanks

You can run it hot all the time... nothing wrong with that. Fire risk is minimal here.

The only time you have to really worry about being hot 24/7 is when you have larger persistent loads that are connected to it all the time. If that is going to be a normal operating condition, then you want to add some battery protection device like a LVD. This is even more important on a single battery system vs a dual battery.

You don't need that much waterproofing... the main reason for all that stuff is to help prevent moisture ingress into the open ends of the wire/terminal to combat against corrosion which would lead to performance issues in the future. This is generally why everything you see in marine applications are tinned.

If you are talking about submerging to the level of where your aux fuse panel is... I think you have other problems you might want to worry about first lol.

This is all low voltage DC... risks across the board are low when it comes to waterproofing.

Thanks for all the help.

I forgot to add, yes I routed the negative cable down the fender line back to the battery negative post since that's the best ground like you said.

The LVD is the next part I'm going to add. Just to refresh my memory, it'll go: positive -> 125A fuse -> LVD -> 100A breaker -> fusebox or is it positive -> 125A fuse -> 100A breaker -> LVD -> fusebox?

The latter would be the way I would route it:
Positive > 125 A Fuse > Breaker > LVD > FuseBox

That said, I would just remove the breaker all together just to reduce complexity and a component... it's not doing anything really other than acting as a switch... and with an LVD, you basically have an automatic voltage based switch...

If you still want a manual switch you can keep using it, nothing wrong with that, but I don't think its going to add anything from a protection standpoint. To be honest you might blow that fuse before that breaker trips anyways.

hey whats up Bumbo, learned a lot from this thread thanks for the knowledge. I'm trying to learn to about adding a fuse box and all that . with your fuse box where did you put the relays ?

The power feed into the relay should be coming off the fuse panel.

The flow of power looks like this in my setup:
Aux Battery > Low Voltage Disconnect > Fuse Panel > Relay > Load

You should also fuse your relay control wire… could be always-on though a switch or ignition controlled. Fuse tap is a popular accessory.