AC300 Split Phase Mode

Hi Everyone.

I would like to check if anyone knows how or when you should plug in the AC Charging cord for the two AC300 when entering Split Phase Mode?

According to the manual, it says "Please disconnect the AC charging cable for both AC300 units while binding into Fusion Box Pro. "

So does this mean that the AC power cords need to be disconnected from the grid, then you make your connections with the fusion box and enter split phase mode under battery power only? Also when do you plug in your AC charging cable? Only after the split phase mode is successfully bounded together?

Thanks in advanced.

I have this same setup. I believe the caution is to prevent feeding both AC300 units from the same phase while changing the settings to Split Phase. At the same time the “AC out” must be off.

After connecting both AC300 units, the “Master” will control the “Slave”, so you power the entire setup from the “Master”. The two lower indicators on the Fusion Box Pro will light up to confirm that the “Split Phase” is working.

I used my multimeter to measure the 240 VAC at the L14-30R outlet (a picture was posted at another page). Then I connected the two AC charging cables to the two diffetent phase inputs.

So have you supplied AC input power to your two AC300’s while in split phase mode yet? If so, what were your steps… did you have to have the AC input cords disconnected before entering split phase mode?


In order to simultaneously charge both ac300 while in split phase mode, you need to acquire a special split phase ac power charge cable from Bluetti specifically for split phase charging. Be careful because The standard 15a charge cable that comes stocked with each ac300 may damage the ac300 if used to charge while in split phase mode and void your warranty. Each unit are in different phases while in split phase and if you charge using wrong phase, that would be an issue.

1 Like

I believe these special ac split phase cable may just become or will become available and probably not many if any ac300 owners have them yet. So to charge these units, go back to single phase mode to charge them and then reconfigure back when done.

I have asked Bluetti about that special cable and they replied that it will be available this month (May). I am building my own version for less. Search my other posts related to the AC300 and split phase operation. I will post new pictures after completing the cable.

Yes, the AC input must be disconnected before setting to Split Phase. And both AC plugs must be inserted in different phased outlets. The best way is to use a L14-30P with a two outlet box, where each outlet is wired to the two live wires seperately.

Here is a picture of my setup:

On the wall, I have the 240 VAC inlet receptacle on the left (the Fusion Box Pro output cable is plugged into it) and the 240 VAC outlet receptacle on the right. I am using a special L14-30P and a prewired yellow dual outlet box from my Libman 7.5 kW gas generator to feed the two AC300 stations in the large box on the far right. That only supplies 15 A each. My construction will replace that part and feed 30 A to each AC300.

Hi Raymondjram,

For my friends setup we have two separate 120v 15 amp outlets that are on two different breakers and are on different phases of the grid power.

Can you provide step by step instructions on how you enter into Split Phase mode with the AC Grid cables… we’ve tried this on our end and our fusion box shuts down after plugging in the second unit and we get several errors (011, 024 and 064 errors).

For example, can you provide us this:

  1. disconnect the ac cables
  2. connect the communication cable between the master and slave units
  3. connect the fusion box pro
  4. etc…

this will help us out allot as we’re struggling to get this working.

Also do you have PV (Solar) charging on your system?


Hi t4602yf,

The Split Phase charging cable is only needed for those who don’t know how to verify and/or deliver two phases of grid power to their two AC300’s. The objective is to take a 240v outlet and split the two hots into two different output outlets, one for each unit. I’ve already confirmed this with Bluetti support personnel.

Good. Sounds like you know what I am talking about.

The ac300 master controls and knows which ac300 uses which phase. The up or down sine wave. My concern is just plugging in a random ac power input from the 2 phases of the outlets, I figure you have a 50/50 chance of getting the right phase to correspond to the right ac300 with the ac power cable. Maybe I don’t fully understand it.

On the L14 devices, either plug or receptacle, one line is marked as “X” and the other is “Y” . So you must assign one AC300 as the “X” phase and the second one as “Y”. Then select one AC300 as “Master” ( I suggest the “X” phase) and the second as “Slave”. The communications cable will let the Master control the Slave, including powering on and off, and keep its output at the opposite phase (180 degrees of the sine wave - some math can explain this). Thus the AC input cables must plug in or wired correctly to the corresponding “X” or “Y” connection. Both neutral wires (white) go to the “W” or “N” connection, and both ground wires (green) go to the “G” connection.

The Fusion Box Pro is also intelligent, and monitors the phases, so its two indicators near the input cables will light up. As a confirmation, the output at the L14-30R outlet will have 230 to 244 VAC (depending on the AC300 efficiency) when measured at the “X” and “Y” contacts. If the two inputs were not in opposite phase the output voltage will be less, and if they were in phase, the output will be zero volts.

The design is well done, but the TT-30 plugs of the Fusion Box Pro and the receptacles on the AC300 are weak and can slip out.