Note: This observation and question is for the AC500, not the AC300 specifically.
After spending a ton of money on the split phase option, I recently read a similar post on the forum before getting the remainder of my equipment to do a test. I did the test, and as expected, I can’t charge from a single phase while in split phase mode.
In single phase, I have not had an issue charging both battery banks from a single phase after setting the amperage to a reasonable setting (12amp/12amp on a 30amp pedestal to meet the 80% continues regulation). This is done with the split phase charging cable and haven’t needed to switch out to the main cable as long as the two inverters are in single phase mode.
This is a little disappointing as the point of the two phase system was to still run 240v/50amp in my RV while being able to charge on a 30amp 120v pedestal when a 50 amp site isn’t available.
After thinking through this, I understand that the system is expecting two phases to pass through to the main panel while on grid vs. having the batteries completely isolate the power source, provide the dual phase output but charge the batteries as needed in a single phase.
We rarely use so much electricity that our batteries couldn’t buffer us during excess usage, deplete a bit, but fully charge while on a single 30amp/120v circuit. But, there are times we have to be mindful of not exceeding 30amp/120v (50amp/120v with my own cable I created to do what I described in single phase).
With that said, I want to confirm the following with the #2 option above. When taking the inverters out of split phase mode to charge the batteries, I believe you also have to kill the AC output as to not provide two independent phases to the RV during the charging period. Is that correct?
If my hunch is correct, I’d say it would be really nice for Bluetti to add an option to turn off passthrough from the grid, allow dual phase on the output side while isolating the input so that it could be charged on a single phase.
Not sure this could be done with firmware, or if the way the hardware is currently designed it’s not possible.