I have an interesting idea about improving my battery charge time on my RV. It’s currently a 12v 30amp system but I have 50amp service at home and use an adapter to reduce down from 2 hot 120v AC lines down to 1. I’ve got 300ah of lithium batteries along with 600w of solar. I’m about to have a Victron 3000w multiplus inverter installed along with a Victron 50a Orion DC-DC charger. This got me thinking, how strange it is that I can charge my batteries faster from the truck alternator (50a) vs plugged into shore power at home (30a) due to my RV’s current electrical system. My idea is to instead install a Victron multiplus II 2x120v inverter/converter but only connect one of the 120v lines to my RV circuit board. In effect this does the same thing as my 50a to 30a adapter, only using one 120v hot line for the output. However in theory the batteries are still getting the increased power (12,000w vs 3,600w) because there are 2 120v 50a hot lines coming into the converter. Of course this requires a new shore power receptacle and cord. Does anyone know if this is possible and if so, what would be the difference in charge times between a 30a converter and 50a converter? I figure it would be over 3x faster since 50a is really 2 120v 50a lines (i.e. 30a vs 100a or 3,600w vs 12,000w).
You ask a good question and I am interested to see how it works out for you. To fully understand where you were going I ran your post through AI for clarity. When expressing power in terms of watts, it seems easier to compare different charging solutions. The AI points out that it comes down to the capabilities of the Mutiplus inverter.
Keep in mind, you also have 600 watts of solar and nominally you will get 350 to 450 watts from it. For the math, your battery is 300a x 12 vdc is 3,600 watt hours. Going from a 20% to 100% level charge requires 2,880 watts. If your solar generated 400 watts, you can recharge to 100% in 7.2 hours. Your 50a B2B at 12 vdc is 600 watts, combined with 400 from your solar is 1000 watts and your 20% to 100% charge is complete in 3 hours, not too bad. These are smart chargers, the last few percent will take longer.
I’m specifically interested in seeing how learning how the 50a Orion DC-DC charger works out. The first Renogy 50a B2B charger I installed overheated and had to be replaced. For the replacement unit I jumpered it to only run at 25a.