Trying to match solar array and controller to 12v LifePO4 battery bank

[TurbineTester]

Victron makes the most popular inverter/ charger for rvs and has a 48v version they released for the us recently. They have a lot of features that are handy for campers like power sharing. Pricey but nice. Others on this forum are probably knowledgeable about other quality inverters that are available. In my case I had neither the budget nor the space for a modular system so I went with an AIO. The AIO has a bunch of peculiarities that reduce it’s convenience In an rv application. It can work really well but it is certainly not specifically designed for this application. Definitely not a set it and forget it system like the victron can be.

I'm trying to sort all these out currently. I already have a mechanical transfer switch built into the RV that switching from shore to generator power as needed when either is available, and uses the inverter otherwise. If i am on shore or generator power, then the current magnum includes a bypass funtion that feeds the circuits with shore power directly instead of battery. So the victron models that include transfer switch like functions for me seem like paying for functions i don't need. There are Quatro Models, MultiPlus, and Multiplus-II so i'm not super sure what i need to be looking at in terms of an exact model.

You can use a buck converter as long as it is large enough to power your high draw loads ( generator, levelers, slides ect. Another option is to ignore conversion losses and leave your converter charger and leave house battery system in tact. I already had a lithium compatible converter charger in my travel trailer so I simply left my original house system in place and swapped out the old fla battery with a 100 ah lifepo4 battery. a buck converter is cheaper and more efficient but more work and you loose the redundancy of a independent 12v power source. For me the extreme power draw of my old style hydraulic slides was the cementing factor in my decision to go this route. I have found the redundancy to be helpful on several occasions.
Before I upgraded from 2200 to 3200 watts of solar I had extra space and dedicated a separate 240 watt panel to charge the 12 volt battery and in this reduced the converter losses by quite a bit.

My current configuration requires the truck to be running to operate leveling jacks and slides, though with my upgraded batteries i know that is not necessary. Even my old house batteries are 2x100Ah BattleBorn upgraded from factory 6v lead acid. If i stay with the old 12v/200Ah house system it could easily handle the load of either the jacks or the slides. The problem comes in with some of the 12v loads i have like the auxillary fridge. How do i configure so to have a house system that still operates at 12v, but can use the 48v/12v buck converter to supplement when the hosue batteries get low?

Adding a 48 volt alternator is the best but I have heard of good success using a dc to dc charger ( like the victron Orion) you just have to be sure not to overtax your original alternator. Upgraded alternators in conjunction with the dc to dc charger are also a possibility.

I looked at what appears to be the 48v/12v and it seems that one of the best models is this one https://www.solar-electric.com/victron-energy-orion-tr-48-12-30a-dc-dc-converter.html which outputs continuous 30A on the 12v side. However, it will not charge a 48v battery from the 12v side. Looks like it only goes one way, 48v-12v, unless i'm not reading the fine print correctly.

 

[TurbineTester]

Reviving this thread again as I’m at the point where I need to order components and start strong it all planned out and wired in. Major things that need to be sorted out are the best way to get the capacity of my 48v bank to supplement the 12v power draws. I’m a little disappointed that the Victron line seems to be limited to 30a current from the 48v to the 12V.

Also I still need to select a 48v inverter to supply power to those high draw loads like the AC units and the microwave.