AC300 to Transfer Switch

I just tried it on my ac300.
I want to revise my previous post.
I turned on both dc and ac power (power to transfer switch running my frig) and unplugged the power chord as suggested.
When on ups mode, and ac300 loses power from the plug, the unit actually stays on battery power and is not rebooted. The dc and ac power stays on and runs on the b300 battery uninterrupted.

After I restored power to the plug, the dc power stayed on and the ac power is turned off. I believe because when power was restored, I received different alarms and I believe the alarm is the cause of the ac power being off. Once I cleared the alarm(s) I can manually turn ac power back on.

I did this many times and one time power came back automatically after I was able to clear the alarm and when the alarm cleared, it automatically turn on the ac power inverter. All Other times I had to clear the alarm and power did not come back automatically and I had to turn it on manually with ac power on/off menu.

Different times I got different alarms.

Most often i received alarm 12 bus voltage high
I also saw alarm 11 H bus voltage high
Also saw 15? Grid voltage low? Not in manual

I did another test with an accessory plugged into one of the ac300 20a outlets and transfer switch into the 30a tt30 port. Power chord plugged in and turned on the dc and ac inverters. I unplugged the transfer switch and just left the 20a unit and then unplugged the power chord, the ac inverter stayed on. If I then plug in the transfer switch into the tt30 port, I get the alarm 12 and ac inverter turns off. Clear the alarm and turn ac inverter back on with the transfer switch still plugged in and ac inverter comes on and everything works. I agree must be something with the transfer switch causing the alarms. But one time I plugged in the transfer switch and the ac300 did not throw any alarm. This is very sporadic.

FYI I tried your experiments and am getting the exact same results on my AC300.

I can confirm I am getting the exact same results with my experiments as well. (I occasionally get those other errors as well.)

I strongly recommend that we all stop until Bluetti responds, I seem to have caused a major failure in my AC300 doing this.

Details: I just tried the split phase transfer switch case simulating power failure and restore of power after reading about the issues on facebook and somebody asking me how mine work given I had a nice long review of the unit.

AC300 Unit 1 - Battery 1, Battery 2
AC300 Unit 2 - Battery 3, Battery 4

L14-30R outlet coming from 240v grid power with 30 amp breaker plugged into splitter cable for 5-20 for plugging in bluetti’ s to grid power

Split phase adapter plugged into cable that plugs into L14-30P Generator inlet plug going to generac 6853 transfer switch (common neutral/ground with 240v inlet).

Test 1:

Running 240v split phase, devices powered on. Transfer switch running from Bluetti’s. Units powered into wall etc. Simulate power failure (unplug power in). Unit’s continue to run. Restore power, AC turns off with code 12.

Test 2:

Same as test 1 but instead used breaker to simulate power failure vs. cabling. AC turns off with code 12

Test 3:

Same as Test 2 except transfer switch is not connected to split phase adapter. All continues running

Test 4:

Same as test 3 with space heater plugged into split phase device. All continues running fine

Test 5:

Same as Test 1 with the addition to space heater running on the split phase adapter but transfer switch is not running the load off the bluetti’s. It is however plugged in. All continues working (I.e. we are still grounded and bonded)

Test 6:

Same as Test 5 but transfer switch has load running off bluetti’s. Upon flipping breaker back to “On” to simulate power restore I get a HUGE POP and the AC300’s have powered off the AC power and now have an 008 and several other errors. I disconnect everything. One AC300 even in single phase cannot power the AC inverter on and just has the 008 (over current protect).

My new error. I have reached out to support this AM. Hopefully they can provide feedback.

Bummer, please keep us posted here. For now I’ve unplugged my unit from the wall and am just using solar to refill it.

Sorry to hear mstang. It’s interesting that the equivalent of Test 5 would fail for me (AC output would turn off).

Support seems quite responsive so I’m sure they’ll get your unit replaced and I hope enough people are demonstrating this now that they can figure out what’s going on.

Something is definitely wrong. The AC300 should continue to output power from the batteries no matter what is going on from the input side. Looks like there are some bugs to work out, I hope they will fix these issues and take care of early adopters like you who pave the way.

1 Like

Yes, will do. Waiting to get a response from support.

Pinging @BLUETTI to this thread. I called support and left a voicemail about this issue yesterday. Here’s the thread I was referring to.

Hi @recycle,

Sorry to hear that.
Can you pls show me how did you connect AC300 and B300? Did you set the following mode? And also pls try to resume to factory setting

I’m not recycle… but I’ve tried all modes (including Standard UPS) and the AC Output still turns off after power returns. I have to clear the high volt bus error then manually turn AC output back on. This is happening to multiple users on this thread. Something is wrong on the AC300 when using a transfer switch and power returns.

I contacted support and they asked for a video which I sent them yesterday. On the video it demonstrates the ac inverter does shut down most times but there are times it remained on. So this is definitely an issue on their side. Otherwise it should not be sporadic with nothing changed other than plugging in and unplugging the power chord.

1 Like

Yes, I have the mode set to Standard UPS. Note that the UPS function works perfectly for devices connected directly into the front AC outputs. It’s just the transfer switch that has problems.

I connect the transfer switch from the TT30 port to a L14-30R port on the transfer switch using an adapter cable (link). I also have tried a connection from the other AC outputs to the switch with a different cable with the same result.

Unfortunately my unit has been shipped back and am waiting a replacement on a separate issue, so I can’t do any testing now.

I have experienced the AC300 ac inverter sporadically shutting off when power is lost and resumed on the ac300 when connected to a transfer switch. I am communicating with Bluetti service but it is slow going. I am trying to get them to have a video call with me intead of pinging emails back and forth with different time zones. Several others on this thread have reported the same issue.

I ran into this internet link that talks about bonded neutral vs floating neutral generators. GFI protection and requiring a different GFI 3 pole transfer switch. I am using the Reliance pro tran/2 30a 10 circuit switch.

Please take a look at this link and the video referred to it and provide any additional information you may want to add.

This was the video that I sent to service that shows the ac inverter shutting off but also instances it remains on when power is lost and returns.

1 Like

Wouldn’t an issue with the neutral continue to trip the circuit? I have a Reliance transfer switch as well… but mine doesn’t trip again after I dismiss the notification on AC300 power returning and reenabling the AC output.

That link makes me wonder if we need a GFI Transfer Switch. Is anyone using one? Maybe the “High BUS” error we are getting is actually a GFI trip in the AC300. Considering how sensitive GFI breakers are, it might make sense. Would also be consistent with how clearing the error easily fixes the problem – just like resetting a GFI breaker…

A transfer switch will only cutout the live wires, not the neutral or the ground. Check the wiring to the switch and to the AC300.

If the transfer switch calls for the neutral and ground wired to be connected to the electrical panel, in my case, it does. Then the transfer switch shares the panel’s neutral and ground wiring. In my case my panel has its ground and neutral bonded. Now connect the transfer switch power inlet/plug into the AC300 outlet, in my case the TT30 30a on the AC300, The plug’s ground and neutral prongs are now connected into the AC300. Now the TT30 outlet’s ground and neutral shares the plugs/transfer switch wiring and is now bonded from the transfer switch/electrical panel which is not switched by the circuit breaker. Now the AC300 senses the bonded ground and neutral. Thus might GFI fault? How the AC300 will behave is in question and service must help here.