I have a 2015 new to us motorhome that needs the house batteries replaced, so I'm thinking about doing some upgrades in the process. I really like the idea of 48vDC LiFePO4 but most of the good inverters are 240v (really 230v) and that is just difficult in NA. There aren't any great 12->48v DC converter options either. I'm looking for feedback on my design that I've settled on. I'm not sure if I can put DC DC converters in serial like I have to charge the house batteries on the road and the chassis batteries while on shore (I do lose the emergency connection switch between the house and chassis batteries, but I have a jumper that works if the chassis batteries are dead).
I'd design a relay network to detect if there is voltage between L1 & L2 (dog bone on 30amp or less is zero volts) to determine if to connect directly to the Quattro or to route through the Autotransformer (need to figure out how challenging it will be to remember to cut the amps in half for the Quattro input on single phase). I'd also design a relay network to enable the 12 -> 48 volt DC path when the engine is running and swap to the 48 -> 12 volt DC path when the engine is off. After drafting this up I realized that I don't need a 24v DC bus, the units can just be connected directly. I don't have enough space to have two Quattros, but the Autotransformers are small enough that I can locate them in other spaces (and cheaper than a second Quattro too).
Happy to have some feedback on the design to understand what I've got wrong or missing. Thanks!
