AC300 split phase recharging

I’m jumping the gun here. Mine are still on the way. But, I’m trying to get everything ready.

When 2xAC300s are connected in split phase, can I charge one battery bank at a time using 120V? We end up involuntary going off grid for 7-10 days every year. My setup should last 4-5 days before needing to recharge. I have a small generator that I want to use during extended outages. It only has 120V out. I estimate that I can run it ~8-9 hours/day(one tank of gas) to keep the batteries mostly charged. I was hoping to charge battery bank A one day and battery bank B next day. Never charging both AC300s at same time.

I know the best solution is to get a 240v generator. I figured the batteries were the most important part for power outages, my wife can easily switch to battery power. But, after buying the batteries I’m going to have to wait a while before any more upgrades to my backup power.

First of all, how many batteries did you buy? Remember, Never charge both units on the same 120 volt generator! The load is the secret, when the power goes out, I cut my load down to the critical units only. My systems could not run 4-5 days with 5 kw solar panels to charge them up during the day. Have fun, my wife thinks this is my hobby and never will pay for the cost of the system.

I purchased 8xB300 batteries. I understand not using same generator on both, at the same time. I wasn’t sure about not having the charge balanced between the two units. I also have the the Smart Home Panel coming. I think the wife will just needs to turn on batteries and flip a switch. We will only have a few “emergency” circuits on the sub panel. My wife thinks the same, about payback. I bet both of them will be happy when the power goes out. My electricity is so cheap, I’m not planning solar panels yet. So, my only payback will be saving the groceries in fridge and freezer.


I live in a cheap electric area too, only 11 cents a kwh. I think our wifes should get together and share their views about our solar systems. Your total batteries are great but solar panels will help. I have 1500 watts (6 panels of 250 watt) on each unit. I have two ep500s and one ac200max with two b230 batteries. My EP500 runs so much better than AC200Max because it has only one battery management system instead of three on the AC200Max. Have fun putting up your system.

Sorry to jump in and little off topic - but you mentioned you like the EP500 better than the MAX, and I am looking at both for steady home use. Two questions:

  1. Any issues with the EP500? Is it a Pro?
  2. How did the EP500 ship? I am a little concerned about getting and handling something that heavy in one piece.

#2 - in a box, I had the same worries, but after two units came, I became an expert in unpacking them. The packing breaks away after you cut all the metal cords around it and then the bottom is a pallet that you can roll off after you break off the white style foam around the wheels. it is very easy to roll around on my floors.

#1 I have the EP500, two of them and they are connected to the split phase fusion unit. The biggest worry is not to exceed 2000 watts, so balancing the load has been fun. I run kitchen appliances on one unit and heater( during the winter) and air conditioner( during the summer) on the other. Never had a problem with overcurrent/voltage, YET.
I bought the AC200 Max because of the lighter weight, but when I run the unit and two B230 batteries, the overhead of the BMS kills the batteries so fast that now I turn off the B230 batteries and use the AC200Max alone. On cloudy days I will add the B230 back in with AC200 Max and charge them with the wall 500 watt power supply. (PS the 500 watt power is plugged into the EP500 that is using the UPS feature.

I hope I did not confuse you, but I would buy another EP500 instead of AC200/AC300 unit.

As described in the AC300 user manual, you cannot charge the B300 batteries through the two AC300 in split phase with two 120 VAC circuits on the same phase. You can do two options:

  1. Buy (or fabricate - I had to buy the parts and fabricate it for my own setup) the special AC Charging Cable for Split Phase that has a L14-30P on one end, and two SP29-30 three pin female aviation connectors on the other. Bluetti sells it for $100. This will allow you to charge both AC300 units at the same time using the two separate phases of your utility 240 VAC circuit. I recommend adding a 40 A circuit breaker to your outlet to protect the AC300 setup. Here is my fabrication.

And here is Bluetti’s offer (they look similar, even with the same connector colors, but I did mine last year, so I did it before Bluetti did!):

With this option, you can still take out 240 VAC power through the Fusion Box Pro for your home while charging at the same time up to 30 A on both AC300 units. But if the utility power fails, the Split Phase operation will drop out and recover five seconds later. This is programmed into the AC300 and not usable as a true UPS.

  1. Take both AC300 units off the Split Phase, and back into Single Phase. You can charge each AC300 independently even on the same 120 VAC circuit, but only using the original 120 VAC cable and dropping the AC input current to 15 A. I had to do this when Hurricane Fiona hit my home, left me without power for eight days, and I used my gas powered generator to charge my batteries. It takes much more time but it is cheaper. After the B300 batteries are charged, remove the 120 VAC cables, then set the AC300 units back into Split Phase and start the AC output on the Master AC300.

I hope this information will be useful for many here who have two AC300 and several B300 units in a Split Phase 230 VAC setup.