My next project was my dual battery system. I have had the Tmax system for over a year now and have not had the time to install it. I have also been designing my system based around how we use the truck and exactly what was needed. Without going into tons and tons of philosophical detail on why I did it the way I did it I will sum it up with the following:
1) I wanted everything to be modular
2) I wanted everything to be professional
3) I wanted everything to be clean and hidden
That said, I probably went way overboard on the professionalism when making my wiring harnesses. I used nothing but the best tools and components. It was a really fun project that took me over a month of tinkering in my garage. Quite therapeutic. It came at a great time while I was taking time off between jobs. It also gave me an excuse to stock up my workbench with fun toys. For a super detailed instructional on a dual battery install you should read klausvanwinkles sticky thread. That is what I referenced for most of what I did.
https://forum.ih8mud.com/threads/t-max-dual-battery-install.607791/#post7820405
The big take away is just keep things clean and take care to make really solid connections with good strain relief. All my wires were grouped together with wire loom and shrink tubing at all the ends.
Here are some schematics of what I intended to do. I stuck to these plans pretty well for the most part. There were a few deviations along the way to simplify where I could. My original intent was to have everything on a switch, even if the device had its own switch. After a lot of internal and external debate with friends I decided that most of the things in the rear of the truck (fridge, lighting, 12V pwr and USB) did not need relay switching and could be hard wired to the fuse block.
INSERT SCHEMATICS
Clean slate
Slee Battery tray
Pulled the Tmax wires through the firewall just to the right of the battery tray
And into the glove compartment. You have take pretty much everything apart to get to the feedthrough.
I drilled a hole in the back of the glove compartment to run the wires through
Put heavy duty velcro on the back of the control box
Attached inside the glove compartment
Battery
The bolts used for the battery tie down bar were too short. They came just up to the bar but not enough to get a nut on there. I had to hack and bend the slee part to a shape that would work. I used a common battery size too. You would think Slee would test with the most common batteries. Maybe I just missed something. Gave me an excuse for a bench vise.
I used a sawz all to cut the verticall walls off and then bent it to shape in my bench vise. I eventually used a grinder to round off the edges that turned out to be razor sharp and hungry for eating 1/0 cables.
Then I tore out every single piece of wiring that I had hastily installed over the years connecting all my devices. That was kind of a do or die moment. It was a total rat's nest of wires all over the place. No order.
There were all kinds of examples of unacceptable electrical work done minutes before leaving for a trip and then never returned to to fix. It is painful to look at.
