AC300 split phase and P030A

The P030A finally arrived and I spent some time testing it. I have run into two issues and am curious if others have.

First, the 30amp outlets on the AC300s which the P030A plugs into are inadequate. The plugins nearly immediately hang out, pull out a little. they stay in, and are usable, but they don’t remotely stay plugged in snugly. I believe this is a quality issue with the outlet. Though I haven’t actually gone and grabbed a 30amp cord from my RV to see if the same problem happens.

Second, the management logic for the split phase load doesn’t distribute the load properly. I’ve swapped master and slave responsibilities just to be sure. Regardless of that setting If I draw 4,000-4,500 watts or so, It puts most of the load on one AC 300, eventually overloading it. One time the split phase configuration put an 800 watt draw from one AC300 and 3,300 on the other. Another time the split phase functionality it put a 200 watt draw on one AC300 and 3,800 on the other. Each time I tested this (4 or more times in the end) I started with ZERO load, added a few hundred watts here and there. Then added a space heater (which pulls 1,500 watts) and a single water pot heater (pulls over 500 watts) and it would never distribute the load properly.

Because of the 2nd issue above it is not possible to reliably pull more than 3,000 watts at a time using the P030A and split phase configuration without overloading the systems.

When I received my P030a, I did some minor testing. I had already purchased 2 tt30 dog bone extensions from Amazon because I did not want to keep plugging in and out on the ac300 30a outlet which could wear it out. I alternated use of my 2 Ac300s and my transfer switch. So the dog bone is always mounted on the 2 Ac300s. When I got the P030a, the cables each plug into the dog bone. I found the dog bone maintained a pretty solid connection between the ac300 and the cable from the P030a. There was very little play as the dog bone plug/interface was flatter and plugged in flat onto the ac300 30a outlet. About $32 for 2, i thought it was a good investment. Photo enclosed.

In regards to the split phase, I used a volt meter and measured the voltage while using the p030a. The 30a and 15a outlets on the p030a outlets measured close the 120v. The L1 to common and L2 to common on the L14-30r outlet each measured close to 120v. However, measuring L1 to L2, I did not get 240v. The voltage kept fluctuating on me. Needless to say, I did not actually use it on my transfer switch. Only my central air on my transfer switch uses 240v. I did not test any further.

If the P030A Fusion box pro does not output the sum of the two 120 VAC lines as 240 VAC, then they are not exactly spliting the phase or 180 degrees apart. There is a trigonometry formula to calculate the sum of the two wave amplitudes from zero to 180 degrees of phase difference. The electronics inside the Master AC300 must keep the outputs correctly as any phase change will reduce that output down to 120 VAC when the phase difference is zero, or at the same phase angle.

I bought the same system but I have not installed it yet. I will also post results here. I do expect the Bluetti/MaxOak engineers to be reading these posts.

Thanks @t4602yf I’ll see about getting the dog bones. I don’t necessarily care about 240, but I need to be able to allow my house to pull 4,000-6,000 watts at least for short periods of time when needed and not have the system shutdown. Not being able to do that defeats the purpose of spending $12,000+ for this configuration.

@Raymondjram I look forward to seeing if you have the same results as I have.

I attempted without success to utilize the NEMA L14-30 plug and socket configuration for the 30 amp outputs since it is a more secure, locking connection and is fairly std. for generator connections. I believe the RV plug was utilized due to the RV crowd being more familiar with that connection type. I would recommend the RV dogbone that terminates on the other end with the L14-30 connection and use L14-30 beyond that point.



Hello everyone!

I am kind of thrilled to be taking delivery of 2 - AC300 and 4 - B300s today.

I went to use the hardware for split-phase 240V operation and powering of our entire service, if not for full off the grid operation, at least during outages, and want to have the 6 kW capability available. We have an 8 kW 240V gasoline generator in reserve that’s quite adequate for this, but of course with the noise and refueling disadvantages.

I ordered the AC300s/B300s from Amazon, as there were some promotions going on. I separately ordered a P030A / AC300 Fusion Box directly from Bluetti on March 6. I received order confirmation, but haven’t been notified of the shipping status of this unit yet.

Now, getting to the point. I am dismayed by what’s being reported in this thread, which was posted three days after I placed orders for the Bluetti equipment. If it turns out not to work properly in split phase, it is a deal breaker for me.

Matt2022, I presume that your split phase data cable is connected and seems to be in working order?

The catch seems to be that it is impossible to test split phase operation without having the P030A package, since this requires the proprietary data cable that comes with the P030A? So, creating a “fusion box” from the requisite connectors, etc., by itself, won’t help.

Accordingly, I am not going to unbox the shipment until I receive the P030A from Bluetti and can test split phase operation. I don’t want to be stuck with something that doesn’t work as (putatively) marketed… there is supposed to be a 30-day return policy, and if it comes to it I will very reluctantly bite the bullet and pay hundreds in return shipping costs rather than be stuck with an $11,000+ setup that doesn’t work as I expected.

I wonder how many customers have received and successfully tested AC300/P030A setups for driving a split phase 240V load?

Please, will someone from Bluetti give some reassurance that I am concerned for nothing? Is the design and hardware for split phase nailed down and usable now? Thank you for your understanding.


Robert, today I hace successfully activated the P030A Fusion Box Pro with my two AC300 and B300 setup. BTW, I ordered on Sept 23rd, and it arrived in January!. Since Bluetti does not ship to Puerto Rico, I needed a transport service for that order to reach me. And it did last week.

Here is a picture of the Fusion Box Pro on top of one of the AC300 units.

The meter shows 240 VAC at the two TT-30 outlets because the L14-30 is connected to my home through a transfer switch. I powered my home for over ten minutes during the test. So if you follow the instructions it will work.

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I did not meter the 2 live sides together of the 2 tt30. I metered the live and common of each of the tt30s and got close to 120v each.

I also did meter the L1 and L2 of the L14-30r on the p030a and got fluctuating voltages. When you get a chance, would you unplug your transfer switch and meter test the L1 with L2 together on the p030a L14-30r outlet? I don’t know why mine reading was erratic. Never got close to 240v.

I did measure at the L14-30R outlet and measured the same 240 VAC.

Today I added two 100 W solar panels to test the DC input and I gained several watt-hours of energy worth a few cents. But tonight I will test the UPS (Uninterruptable Power Supply) operation on my whole house, when I transfer the entire electrical home load from the utility to the AC300 setup. I will check the system tomorrow morning. If all goes well, I will continue the UPS operation for a longer time.

Eventually I will add an initial 1.6 kW (four of 400 W) of panels then grow to the full 6.4 kW (16 of 400 W) that will cover my home completely by solar power.

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Thank you. I must have done something incorrectly.

Raymondjram, thank you so much for your reply! :slight_smile: That is reassuring. I reckon that you tested the AC voltage while both legs had at least a few hundred watts of load on each?

I am still waiting for my P030A to be shipped.

What model of PV panel are you using, if you don’t mind saying? I am planning to have something similar once I receive the P030A and the rest of the system connected.



I have no panels yet. I am using my setup as a UPS because we get many blackouts. Our utility (PREPA) suffered damages in 2017 from Hurricane Maria, so it is weaken. Thus the need to keep power on with the setup.

Raymondjram, thanks for the reply (sorry to take so long to respond). Robert

As for the “AC Charging Cable for Split Phase” which is item 14 on page 6 of the AC300 user manual, I ask Bluetti if they have finally decided to produce and sell this special cable. I have been searching for the special Weipu Aviation Connector SP29 (as labeled on the connector) for the 120 VAC 30A inputs to the two AC300 units. The other end is a L14-30P male that any hardware store sells, plus the needed feet of cable. I know how it should be wired for the Split Phase application.

I have checked Weipu directly and other suppliers for that connector (SP2910/S3) which is a female plug with three solder pins. Most sites, including Amazon, only sell the male plug. Has anyone else found a source for the connector?

Has anyone actually successfully pulled 4,000-6,000 watts via the P030A with the load being properly distributed between the 2 AC300s? Instead of most of the load on one or the other and causing a shutdown?

I wanted to follow up on my experience with this setup in case someone else finds it useful. The overall outcome was positive but there were some unexpected quirks on setup.

It took several months to receive my P030A. I anticipated getting it sooner; but after April I just didn’t have the time to return to this project until this month (October 2022). So, since March 2022 my 4-B300s and 2-AC300s have sat in their unopened shipping boxes in my basement.

When I finally unboxed them a couple weeks ago I was happy to find that the battery indicator LEDs on three of the B300s showed 80 percent and on the other B300, 60 percent.

When first connecting the units one of the AC300s showed a communication cable fault alarm. I swapped the cables around and finally cleared the error by using the lower connection port on the alarming B300.

Eventually I powered down and swapped the cable back to the B300’s upper port, and this time it didn’t alarm. However, in the Bluetti app, it referred to the batteries as number 1 and number 4, whereas on the other AC300 it called them number 1 and number 2… strange.

One thing I found extremely annoying is that in the iOS app, when trying to enter the WiFi credentials (entering the WiFi SSID name) it kept taking me to the iOS WiFi Settings panel on my iPhone - I could find no way to directly type in the WiFi SSID!

Maybe I am not understanding something, but other IoT devices allow typing in the WiFi SSID directly. I wanted to do this because I created a separate 2.4 GHz WiFi network to keep the Bluetti WiFi isolated from the rest of my WiFi LAN. Seems odd that it kept bouncing to the iOS Settings rather than just letting me type in the SSID for the WiFi. It did allow typing in the password, however. I wasn’t sure if it eventually connected, but it must have, since it allowed updating the firmware.

I charged the batteries to somewhere in the 90 percent range using the 120 V AC utility cable, then connected the P030A.

As a test before trying to power my house’s electrical system (- gulp -), I purchased a 240 Volt, 4800 Watt space heater and used that as a load. Measuring the split phase voltage gave 240 Volts; the AC300s indicated almost 2400 Watts each (see photos), so everything seems to be working as it should. Under load the readings on the “opposite phase” 120 V plugs on the P030A with respect to neutral were each 120 Volts (no photo of that).

Strictly speaking this might not be a thorough test because I believe the space heater’s heating element isn’t referenced to neutral. The 240 Volts is “bridged” - the heating element is driven directly by the X and Y phases but floats with respect to neutral. A home’s split phase for 120 Volt loads would reference each phase to the neutral line. But at least it shows the AC300s can deliver decent split phase output power, and that the 120 Volt legs have the proper inverted polarity. I reckon 240 Volt appliances like a well pump don’t return the load on the neutral either, but run one leg against the other, just like the space heater? Someone who knows about that, please correct me if I am wrong about that.


You are partially correct. The two lines are 120 VAC when referenced to the neutral which is grounded at the panel but add up to 240 VAC because they are in opposing phase. A simple explanation is that one line is at the opposite polarity of the other because they are outputs of a rotary generator at 60 Hz, which is 60 cycles or turns per second, equivalent to 3600 revolutions per minute (RPM). So the utilities are creating an altenating current or AC that flows in alternating directions sixty times each second.

When one phase is at +120 V the other is at -120V so the relative voltage is the total or 240 V. Same when they alternate to -120 V and -120 V. Since this alternation is changing 60 times a second, we then define this as 240 VAC. Current flows back and forth between both lines.

The two AC300s must recreate the utility power from the DC power supplied by the B300 batteries. When standing alone, the AC300 generates 120 VAC. But for 240 VAC, the two AC300s must do it in sync and at opposite phases, hence the Split Phase function. The communications cable is the link to sync the AC300s, but the setting of a Master and a Slave decides which unit will lead (generating the 60 Hz signal) and which will follow in an opposing polarity.

The P030A Fusion Box has two functions. First it takes the 120 VAC from each AC300 and wire them as X and Y to the L14-30R outlet (you can trace the paths with an ohmmeter or continuity tester) for the 240 VAC output. Then it has a special circuit to detect the phasing. If the phasing is correct it turns on and illuminates the two LEDs. At this point the L14-30R will supply 240 VAC, neutral, and ground to the load. These last two lines are common to both AC300 units.

If the two 120 VAC lines were not in opposing phase, the output will not be 240 VAC, and if used, this may damage one or both AC300 units. As for the neutral, this is needed for 120 VAC loads. So if the Fusion Box load uses one 120 VAC phase more than the other, the current difference flows through the neutral. You can actually measure this if you measure the current of each phase. A balanced load with have little or no neutral current, but an actual home have a variety of 120 VAC loads, so there will always be an alternating current flowing though the neutral wire, which will return to the utility.

I hope this helps explain how the AC300 Split Phase operates. For your knowledge, I am a licensed Electrical Engineer with 48 years of experience.

Hi Raymond, thanks for the explanation. I understand how the P030A/AC300 combination works, having designed numerous linear and switching DC and AC power supplies and differential output / bridged (which is what this is) amplifiers; though others will find your explanation useful.

My question involved well pump motor design. The behavior of the bridged AC300s might depend on whether the load presented by the well pump motor is returned to common/neutral (e.g., the motor armature has two separate driving phases that each are referenced to neutral), or, to the other AC300 (e.g., the neutral doesn’t carry any current in the well pump armature).

In the latter case, each AC300 has to not only source current, but sink the current from the other AC300, and coming from a motor, that current has a reactive impedance.

Anyone who has experience with hi-fi systems and has used bridged amplifiers knows that certain loudspeakers are more challenging to drive than others, and that is because of their reactive impedance.

Accordingly, driving a motor is a far more realistic, but stressful, load for the AC300s than my simple 240 Volt, resistive-load space heater test.

As an aside, very sorry my messages seem to consist of one, long, run-on paragraph. But, the punctuation gets stripped out and there doesn’t seem to be a way to avoid that. Maybe I have to embed html formatting in the text? (yes, that worked.) - Robert