Connecting power to solenoid for aux. power

[Optimistic Paranoid]

And here is where I think the 2AWG cable will attach? There is a boot on the RED cable there, and I believe a nut under it.
I stuck my phone up in there for this shot, It's gonna be really tuff to get in there...

Yeah.

From an ELECTRICAL point of view, I completely understand where Sternwake is coming from.  The original factory wire from the alternator to the engine battery is a bottleneck that prevents getting the maximum current out of the alternator.  That's why he recommends drawing power from the alternator instead of the engine battery.

Thing is, from a MECHANICAL point of view, it can be a cast iron bitch getting TWO big, heavy wires on these modern alternators.  It would have been a lot easier in the old days - I miss all the room we used to have around engines back in the old days.

As a compromise, if you take the original alternator to engine battery wire off and have a new one - with the right ends and length - made up out of wire about two sizes larger; you can run THAT from the alternator to the battery, and then hook your house battery up to the engine battery and you've gone a long way to minimizing that bottleneck.

If you can get a similar size wire made up and run it from one of the bolts that mounts the alternator to the ground post on your engine battery, that will help even more.

Or just tie the two batteries together - which is frankly what most other people do - and accept the fact that you are not getting maximum recharging from your alternator.

As far as what size fuse to run, that depends on what size wire you are using.  2 awg  - and not 2/0 awg, right? - and 100 amps should be good.

 

[galladanb]

OP Says...
It would have been a lot easier in the old days - I miss all the room we used to have around engines back in the old days.

As a compromise, if you take the original alternator to engine battery wire off and have a new one - with the right ends and length - made up out of wire about two sizes larger; you can run THAT from the alternator to the battery, and then hook your house battery up to the engine battery and you've gone a long way to minimizing that bottleneck.
No kidding! I loved working on my old 79 Pick Up. I could crawl in there and have a seat.
SO I COULD THEN HOOK UP AT THE BATTERY?

If you can get a similar size wire made up and run it from one of the bolts that mounts the alternator to the ground post on your engine battery, that will help even more.
THE CABLE AT THE BATTERY HAS TWO CABLES MOLDED INTO THE POST CONNECTOR, UNSURE ABOUT MODIFYING THAT? IT WILL TAKE MANY MORE Q&A FOR THAT WAY, RIGHT?

Or just tie the two batteries together - which is frankly what most other people do - and accept the fact that you are not getting maximum recharging from your alternator.
NOT SURE WHAT YOU MEAN BY TYING THEM TOGETHER? I THOUGHT THE WHOLE POINT WAS TO ISOLATE THEM?

As far as what size fuse to run, that depends on what size wire you are using.  2 awg  - and not 2/0 awg, right? - and 100 amps should be good.
YES, 2AWG AND NOT 2/0, THAT STUFF IS MONSTROUS!!!! LOL!

OP, THX FOR CHIMING IN HERE! I WAS HOPING YOU WOULD, AS I FEEL YOU OFFER VERY WISE COMMENTS, AND ARE NOT CONDESCENDING OR HATEFUL!!!!! THANK YOU SOOO MUCH!

 

[Optimistic Paranoid]

NOT SURE WHAT YOU MEAN BY TYING THEM TOGETHER? I THOUGHT THE WHOLE POINT WAS TO ISOLATE THEM?

The solenoid ties them together when the engine is running, and separates them when the engine is not.

 

[Optimistic Paranoid]

THE CABLE AT THE BATTERY HAS TWO CABLES MOLDED INTO THE POST CONNECTOR, UNSURE ABOUT MODIFYING THAT? IT WILL TAKE MANY MORE Q&A FOR THAT WAY, RIGHT?

The original factory cables were not designed to easily add more wires.  I replaced mine with a pair of military battery terminals:

https://www.amazon.com/Pico-0810PT-...746&sr=8-2&keywords=military+battery+terminal

This required me to replace both the original starter and ground cables with new wires that had eyes on each end.  In addition to running a wire between the two batteries - via solenoid - I had to hook a winch up to the battery also.

 

[highdesertranger]

military terminals are the bomb. translation. they are great. highdesertranger