question

Hello,
Did you have a look at the 12V->48V @70A (BB124870) Sterling Power Battery to Battery Charger ?
https://www.sterling-power-usa.com/SterlingPower12volt-to-48volt-batterytobatterycharger.aspx

A lot of losses and conversions going on.

Take a look at https://www.safiery.com/

They have 48v Alternators and some bi-directional DC/DC devices that are rather cool. All CANBus controlled and can take 3Kw at 12v and convert it up to 48v, to do just what you want.

I wanted to go this exact route for the exact reasons you mentioned as well. Then after months of online research and conversations with people that sell and install these systems for a living i elected to go the 12V route because of the following.

#1 Keep it simple (fewer parts to break on the road)

#2 Off the shelf parts availability

#3 No conversion losses 12-> 48 and then 48 to 12->

#4 For my RV most items are 12 volt except microwave and AC which are not used often so i was designing the 48V for the exception not the rule

#5 LifePO4 battery configuration / upgrades are simple as being in parallel

#6 Dual 2/0 or single 4/0 Welding cable not difficult to crimp and easy to route even in large gauge sizes

Good luck with whatever option you choose.

Hi .

I have reviewed your diagram , nothing wrong with it , it can be done .

Still, i would have some suggestions: regarding the alternator i would strongly suggest an external voltage regulator , victron has one that is compatible; the cable sizes should be big enough to accommodate the high amount of power that goes through them , both + and - should be the same gauge and lenght .

Expect real losses from 12v to 220v at the 1st inverter , which i assume you know , should be an off grid inverter with a sine wave capable of handling nearly 90% of what alternator can produce .

Other than these , except for details like fuses , isolators ..., the diagram can be done , if done properly .

I highly recommend to check youtube regarding the external voltage regulator that victron has , it's a game changer :

https://m.youtube.com/watch?v=jgoIocPgOug

PS : i am not affiliated or sell victron products in any way .

And 1 more thing : for 12v appliances you don't need the orion when the engine is running just make a circuit from the alternator just before the entrance in the 1st inverter .

For when it's off just fit an automated switch after the orion so you don't power the alternator from batteries.

However , do you have a particular reason to go with a 48v multiplus ?

When you have 24v batteries you have the option to go for a 24v inverter ....

I haven't checked but i assume victron has something like that ....just saying .