AC300 Split-Phase setup questions

You’re welcome… I’ve spent allot of time putting my system together and figured I could share the knowledge.

As for the bonding plug. Even though in the video I show the use of the fusion and two bonding plugs, I am actually not running that setup. I decided to remove the fusion from my setup so that my ground passes to both master and slave. With this I’m able to use just one bonding plug. I’m also doing this because I want to run a surge protector/voltage regulator between my AC300 and transfer switch.

I would love to see this setup if possible. What surge protector/voltage regulator are you using between the AC300 and your transfer switch?

I’m currently running a Hughes Power Watch Dog for my incoming AC from the Grid to charge the AC300’s:

And I will be adding the Hughes Autoformer that is both a Voltage Booster and Surge Protector. The only thing is that you can not use the fusion box with an outbound surge protector, so I’m using my y-adapter:

I have a RV type watchdog (50A) that I thought about using for surge protection between my panel and AC300 Y cable.
Did you hard wire it in or are you using adapter plugs?

I have adapters to take mine from 30amp to the 50amp that are wired in my home. I am prepared to replace my head units to the AC500 to upgrade to 50amps.

Ok, so let me see if I understand where you are at right now with your two AC300’s:

You’ve eliminated the AC Fusion Box from your Split-Phase arrangement and will be powering your manual transfer switch using your own merged cable that plugs into the 30 Amp outlets on the AC300’s and merges together and plugs into your inlet box for your manual transfer switch - correct? Are you still keeping the communications cable - is it still required?

If the above accurately describes your situation, then your able to run split phase operations with your two AC300’s without the use of an AC Fusion Box from Bluetti and have instead opted to use your own merging output cable to power your manual transfer box for the purpose of having your ground passing to both the master and slave AC300’s - correct?

If I don’t need the AC Fusion box and can still do split phase operations, I’d like to send it back since I can get a refund on this very expensive cable while I can (my return window expires on 2 Sep). I too want to put some type of surge protection between my AC300’s and my manual transfer switch since my experience has already resulted in $2k of damage to my Air Conditioning blower and transformer.

Can you explain how your new setup achieves the ground to both master and slave without the AC Fusion Box?

As always, I appreciate your feedback.

Yes, this makes sense since mine is probably the same type setup. I just thought there was some other type of ground that you might be using for the AC300’s as well. I checked my gas generator for a grounding point and noticed it had a grounding point on the front of it that I had ignored before and certainly didn’t use it last winter when I was actually using it to power my house emergency circuits - probably need to use it.

Sorry for my delay.

Yes, I am not running the fusion in my setup. However the communication cable is still required for the two AC300’s to negotiate into split phase mode. I don’t think you’ll be able to return the fusion, as you’ll still need the communication cable that came with your fusion.

I’m running a TT-30 to 50AMP y-adapter. Each TT-30 plugs into the AC300’s and then the output is a single 240v 50amp RV style outlet.

I choose setup this for a couple of reasons:

  1. this allows the grounding from my transfer switch to pass back to both AC300’s. The fusion blocks one unit.
  2. this allows me use a single neutral bonding plug on my setup to ensure my GFCI/AFCI components work correctly.
  3. this allows me to add a voltage booster and surge protector between my AC300’s and my transfer switch. The fusion will not allow you to use a surge protector.

I’m still going to keep my fusion as a back-up or if I find a reason why I need it… but the voltage booster has been a great plus in my environment…

No problem. I always appreciate your feedback. Yes, you are right - I cannot return Fusion box since it coupled with the comms cable - frustrating.

So I didn’t realize you couldn’t use a surge protector between my AC300’s and my transfer switch with the fusion box in the mix - darn. I was going to use (see below) this in my TT-30 outlets and then plug in the fusion box given my past issues with over-voltage from the split-phase setup frying my furnace blower motor and transformer. I am assuming you tested this setup and what happened? Did the fusion box just not receive power from AC300’s?

When I tried to put my surge protector between the fusion and the transfer switch the AC300 master threw a low voltage error. Now my surge protectors have a outlet tester built in… so that may have been the issue…

Well, I’ll give it a try and lets see what happens.

I am now running a surge protector between grid power and the AC300 grid power.
I have not seen the 025/026 (short / open circuit) error since.
I know it is not the same as the output surge protector.
I dont see any reason a protector on output would not work. Let us know what you find @Tjcampbell06

Just ran my AC-300’s in split-phase to my manual transfer switch using the Bluetti AC Fusion box, but put surge protectors between the AC300 30amp outlets where each plug from the AC fusion box plugs into the AC300’s and then turned on AC out power and shazzam - the surge protectors status and protection lights illuminated just as advertised and my AC Fusion Box LED lights clicked on just as advertised.

I then plugged into the L14-30R on the AC Fusion box and connected the other end to my Generac HomeLink Manual Transfer Switch L14-30 receptacle, but not before I turned off my furnace breakers on my Manual Transfer Switch (just in case). The Generator power light on the manual transfer switch lit up just fine. I then pressed rocker switch on manual transfer switch and transferred emergency circuits to my AC300’s and everything worked like a champ!

I let this setup run for about an hour and everything was great with surge protectors working as advertised and AC Fusion Box working as advertised.

I turned off power to each of my furnace blowers at the attic switch that connects to my manual transfer switch in the garage. I then went back to the garage and turned on furnace blowers 20Amp CBs, everything still good. So I went back to the attic with my multimeter and measured voltage on the inbound side of the attic switch and it was a steady 120 VAC on both circuits being powered by the AC300’s. I even measured the Hz using Sine wave function and it was a clean 60 hz signal. So I took a deep breath and switch both furnace blowers on one at a time and everything worked fine - whew!

So it appears that my outbound surge protection using the AC fusion box is working. My next challenge is getting my grid power receptacle installed by my electrician and using surge protector between the panel and my Bluetti AC Split-phase charging cable.

Both my AC300’s have bonding plugs in them and both have surge protectors between the 30 amp outlet and the plugs for the AC Fusion Panel.

Success for now. We’ll see how this whole setup works one the AC300’s are not only connected to the manual transfer switch, but also connected to grid power for charging as well.


I take cash tips :slight_smile: … j/k… glad you’re working!

Thanks @Tjcampbell06 for sharing.
this is encouraging.

Everyone still running good? No issues?

Everything is good so far, but my setup is only half done in that I’m powering my manual transfer switch, but not charging via the AC charging cable since I have no receptacle to do that yet (electrician installing that next week). Then we’ll see if the UPS function works with charging & discharging happening.

Well I jinxed myself by asking… I was asked to test the latest firmware version by Bluetti Engineering today to see if it would resolve the last remaining issues on surge loads when in Split Phase… and pop, 008 Over Current error. So I’m down until I get a replacement … bad timing, my solar panels are getting installed on the roof in two weeks.

Sorry to hear about your unit. What kind of Solar panels are you using and are you using micro-inverters with them or just pushing DC voltage directly to your AC300’s?

Ya it sucks… I think I’m done risking my own environment helping Bluetti R&D test and fix the split phase issue. Unless they send me a test unit, I can’t afford to kill my own equipment.

I’ll have to lookup my panels tomorrow… But if I remember correctly the AC300 isn’t compatible with micro inverters. Its in the manual what it doesn’t work with…