Current dual inverter setup need help optimizing


Solar Addict
Dec 18, 2022
I need help with some out of the box different ideas on how to best optimize my current system to fit our needs. We use this coach a bit differently than most as we typically do day trips or weekend camps. Usually we'll drive a couple hours to an all day auction or amusement park then either work from the coach or make frequent trips to it while its in a parking lot. Sometimes we'll camp overnight at a CG or try boondocking if we have multiple events far away. We also use it to travel long distances with groups of people inside and plan on leaving it for 1-2 weeks at a time out of state.

Initially I bought a 2000 Discovery RV and started fully customizing it but realized it wasn't the best fit for our needs so found the perfect vehicle a 08 Prevost XL2 (link below) Its different than most as its very expensive and well built for commercial use and has huge windows that bring in a ton of sun/heat. Its basically couches and tvs. We're working on some remodeling to better fit our needs but keeping this similar style. So far we've cut the wall on one side so we can have full windows on both sides and added a huge residential fridge. Plan on adding a shower in back room, sink on counter area then mainly cosmetic things to upgrade the look.

The 12V only has water pump and LED lights. There's a separate 12V genny start battery (has merge option with 12V house) and the starter batteries are 4x12V in series parallel for 24V using a vanner to pull 12V engine loads and equalizing. House 12V goes through a firefly system that I'm planning on reconfiguring and being able to access remotely. I have a full internet setup with starlink, pepwave and LTE with 4 WIFI's onboard and POE switches. Currently they're on 12V with a 12 to 48V converter but maybe I can put on 48v batteries now.

Everything is 120v and no need for 240v, although a buddy plug would be nice, but i guess ill just use a 30a one. All wiring is overbuilt with basically separate 20a breakers for each outlet. I have 6 AC units and they're different types and sizes. I'd like the ability to use 4 AC units off battery and all 6 when on genny. We might leave this thing out west for a couple weeks at some airport parking lot in the hot sun and want to be able to remotely turn on a few ACs when we land then when we get to it fire up the genny and turn them all on so we're not cooking waiting for it to cool off.

I considered switching everything to 48V but think having both a 12V and 48V system makes the most sense, plus I already have all the equipment and no point buying more I don't need. I have a CerboGX for each system but need help figuring the best way to optimize both systems so I can use all my resources effectively. Currently below is how its setup, although I only have 1800w solar installed but have both the 100w and a bunch of 320w panels at home just trying to decide if its worth ripping out the already installed ones just for a bit more wattage. I just got the 2nd CerboGX so installing that today.

Problem: I'm only using 1 leg of 50amp shore.

Solution? I'm thinking about installing a 2nd 50amp shore connection so both have a 50amp plug then I can use adapters and run one at 50amp and other at 30amp when at a CG pedestal as they have a 50amp/30amp and 15amp connections. move the 48V to 12V inverter to in2 so then when I plug the 50amp shore into in1 of the 12V it'll use all 50amps plus the 5000w inverter when connected PLUS I can plug 15 or 30 amp plug into the 48V inverter and it'll charge those batteries all up.... although this seems kinda pointless because the 48V inverter won't be inverting anything and has a ton of solar so it'll fully charge even if its storming, and if I'm at a CG i'll be there more than a couple hours.... so maybe do this with genny instead since it can use both legs and they're 100amps so i only need it on for a couple hours to fully charge both banks. I also have a huge custom ATS that I bypassed so could use that somehow with the 2nd shore plug and be able to have both the genny and 2nd shore sharing in1.

Problem: 48V feeds into the 12V so the 12V is always at 100% charge which makes my alternator pointless since I do mostly day trips when I only had the 12V system it was really nice being able to run 1AC and it still fully charge the batteries while driving. There will be many times where we'll want to run 2 or 3 ACs while driving so having the 270amps from alternator would keep from draining my 12V but this will only help when my 48V is drained.

Solution? Somehow set the 12V to only charge to 80% using the other inverter (L1 in). This way when driving the alternator is pumping above 80% and using its resources so parked it'll always be 100% 12V and when it gets to 80% it'll drain the 48V which uses solar to charge. I lose 20% of my 12V capacity most of the time and lose solar while driving if 48V is 100%. Also limited to 5000w when above 80% but once below that it'll use both inverters which would be fine.
Other solution? Use some of the relays and inputs on the inverters or cerbo or wakespeed through canbus to communicate between the systems which is best to use. Ideal logic would be something like IF alternator is on AND usage is under 2500w AND charge then turn off in1.

Couple other things: The only times i'll be using a lot of electricity is for heating or cooling. I have 2 microair smart thermostats that control 4 of the AC units so might also use their system for some logic or the firefly as it has 3 12V digital switches for the AC units already setup. The genny will turn on/off using the CerboGX once I run a pair of wire to its autostart. I have 3x 12V 24AH little lithium batteries laying around with no use and I believe I have room to add 1 more rack battery. All of this is in the front bumper area of my coach which is designed to hold a huge tire, so is very deep and wide but not very tall, like 16" but gets to 24" behind a brace so I have most batteries mounted vertically, then the Lynx infront of them and finally the Quattros up closest to the opening sideways. I'm hoping packing them in pretty tight with space above them allows them to keep warm in winter but still room to keep cool in summer. I have plenty of room to add tank heaters underneath and/or fans above to help with airflow but temps haven't been any issues yet.

I seem to have another problem, its using shore power instead of solar when solar is in float and Soc is 100%. It should prioritize solar over shore but I think with the lynx shunt it doesn't communicate with DVCC like a smartshunt. I manually changed it to inverter only and all is good but wondering if I should also have my 48V set the same 80% like i'm considering the 12V for the alternator.

Might need some geofencing logic because I only really care about electric usage when at home.