RV system Upgrades - Newbie Questions

[Java Jack]

OK...been doing a lot of research but not finding anything specific to my questions.

Just bought a new 20'6" RV and want to upgrade the single lead acid battery to Lithium. Many of the places we camp don't have shore power and I could be out for up to a week at a time. I want to be able to run the A/C for a few hours as needed to cool the trailer down on really hot days. I know I won't be able to run indefinitely and that is OK...I just want to be able to extend the run time using combo of solar and small generator.

To that end, I bought:
2 x 300ah Epoch Essential batteries (specs say 200W max current with 400a/10 seconds)
1 x Victron Smart Shunt
1 x Renogy 400W solar Suitcase
1 x Honda 2200i generator

Still to purchase
Solar Charge Controller (not sure if I should get the Victron 100/30 or 100/50
Victron Multiplus (I think the MP II won't fit my space)
Solar Switch
Lynx Distributor (and fuses)
Class T Fuse (not sure what size I need)
Cables (not sure what size I need)
May add Cerbo GX and Touch 50 (haven't decided yet)
Attached is the potential design I came up with after research

The space everything is mounted in is pretty small (about 3 feet long x 18" wide and 18" tall. So all the components will be pretty close together for short cable runs. The fuse panel is about 3 feet about the battery compartment so it too is pretty close. The run from the shore power port to the compartment is about 8-10 feet. Trailer has 12V fridge, pump, stereo and a handful of USB ports around the trailer. It has AC plugs, A/C, Microwave (but will probably be removed), furnace and TV. I will likely add at least 1 intake fan and 1 exhaust fan that are thermally controlled to try and keep compartment temps down.

So my questions are:
Given the short runs for the battery to the lynx (no more than 1.5 feet), Lynx to chassis ground (about 2 feet), Lynx to Inverter/charger about 1.5 feet...Should I be looking at 2/0 cable or 4/0 cable?
How do I size the battery fuse?
How do I size the fuses used in the Lynx for the different loads?
How do I size the Solar Controller (100/30 vs 100/50)?

Any help is greatly appreciated.

Regards,
Java Jack

 

[DIYrich]

So my questions are:
Given the short runs for the battery to the lynx (no more than 1.5 feet), Lynx to chassis ground (about 2 feet), Lynx to Inverter/charger about 1.5 feet...Should I be looking at 2/0 cable or 4/0 cable

Bigger is better, especially for the amps you may be using.

How do I size the battery fuse?

fuse protects wire. I would use 4/0 wire and fuse it for 250a (3,000 watts at 12v, with surge to 300a for a few seconds)

How do I size the fuses used in the Lynx for the different loads?

Fuse protects wire.

How do I size the Solar Controller (100/30 vs 100/50)?

Panel wattage. One 400 watt panel is 33 amps at 12v. 30a probably works, as you are likely not to get the full 400w. The 50a allows you to add a second panel. Since space is a premium, you don't want to add a second charge controller if you expand.

 

[Java Jack]

Thanks. Another question when putting batteries in parallel. Only 2 batteries being used. Does the positive cable need to be the same length as the negative cable? I'm placing the batteries in a L shape which puts the neg. terminals close together (about 4") and the positive terminals further away (about 9"). I want to keep the cable runs short as possible. I know when doing 3+ batteries all the + need to be the same and all the - need to be the same but can't find anything that specifically states that the + needs to be the same as the - cable lengths.