This is simulated power outage by unplugging the power chord and replugging. Also have used a wifi switch to turn power off and on. Same results.
Thats great news about the “New” AC300. I have had (2) AC300 with the “kiss of death” 008. Got my second alarm this morning. I have (1) AC300 and (3) B300 batteries. Ordered another B300 a couple days ago, but cancel my order this morning after the 008 alarm. I bought my Bluetti equipment through SSK.com. they are work with Bluetti for replacement. I’ve had the second unit a week. I’ve read this whole string on “AC300 to Transfer Switch”. Also using Tran/ Pro 2, 310A not a good match so it turns out. Hopefully the NEW AC300 will fix this problem.
I should add that I got the 008. OCP (Over Current Protection)-Hardware alarm on Solar. My AC300 was not plug into the grid. Solar through the Bluetti PV step down transfer D300S, from roof PV panels.
This pretty much defeats the U in UPS.
A UPS should be uninterruptible before, during and after a power event.
Could you imagine if your data-center for (large company) went off line when power was restored?
I have read through this thread and maybe I can add some more info.
I have 2 AC300 in split phase. They are fairly new (since May 2022).
They feed the Bluetti Fusion box and are fed by the Bluetti AC cord for Split Phase systems via dedicated 30A feed.
Both are running current mainstream firmware (not the new one suggested up the thread)
I experience intermittent shutdown of the AC output. When this happens and Grid power is restored I get a error on master of High Voltage and relay errors on slave. This would suggest an grid power event of some sort. It is pretty much the same errors I get if I kill grid power at the breaker and then turn it back on.
Not seen the Error 008. Not sure if this is because of “new” AC300s.
With the loss of AC power, the units continue to provide AC output. It is when Grid power comes back on that I get the errors and AC output shuts off.
The Fusion box does feed a Reliance transfer switch which I have not had issues with it feeding my critical circuits (lights, refers/ freezers, etc ). I do like the flexibility of turning on / off circuits when needed. Also, not seen the issues stated above by others due to the transfer switch.
I hope this helps with this issue. I just wish I had found this forum earlier.
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what you are experiencing in split phase mode with the ac output staying on when Loss of power and ac output turning off when power returns is consistent to what recycle and I experience except we tested in single phase mode. I believe Both recycle and I have the reliance protran2 transfer switch as well.
I have tested my single AC300 connected to both sides of my ProTran 2 10-circuit transfer switch. (My two 240V loads are set to “Grid”.) I didn’t generate any errors. It’s been a few months now but I believe that I tested it running some light loads while charging it from AC. But I may be wrong, and now I’m reluctant to try it.
I bought my AC300 in mid-April. Is there any way to determine if it might be a “new” one capable of utilizing the non-neutral-switching ProTran switch?
And is Bluetti continuing to replace AC300’s that have been killed by using these switches?
So yes. Bluetti Engineering informed me yesterday that they are sending out new units. These new units have been physically changed to support transfer switches that do not switch the neutral wire.
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Do you mean they’re replacing people’s units under warranty? And does it have to have failed first?
It appears so. They are contacting people who have these units…
I tried to get a date on when they started to sending out new units, so we know which one we have… however I know a few people that have already been contacted to schedule replacement.
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It may be that I have an old one and a newer one.
The first one I got gets the high voltage error. The second one just get communication errors because the old one errors out and shuts off AC. (this causes both units to shut off AC output in split phase)
I did some experiments swapped grid inputs, changed slave and master.
Also did a factory reset and ran in single phase mode, standard UPS etc.
In every case the older one would error and shut down. The newer one would keep running (if not in split phase)
That’s useful information. Thanks.
I was just told by Mike at support:
" As we all know, the AC300 is a offline UPS with a switching time of 20ms. The AC300 cannot switch to 0ms like an online UPS. But I will report this problem to our R&D department and see if our r&d colleagues have a newer software to solve this problem."
So it will always trip on/off when the power comes back on since it has such a long switching time.
The whole point of a UPS is (Uninterrupted Power). No idea why they market it as such. If they put in the ad’s description; Warning: This unit will switch off your devices/power when the power is restored. I bet they wouldn’t sell any at least to folks who want to use it as a whole house UPS.
I’m hoping their R&D department does figure it out as it’s totally false advertising.
I can live with a 20ms delay. It may not keep my TV and computer running but it will keep my fridge and freezer running.
I cant live with the AC output power not being restored automatically.
However I agree, this is not a true UPS.
My testing does not agree with Mike. With my newer AC300 I do not see the AC output go away at all. (can you actually see a 20ms delay? 
) This would be testing with it in single phase and not connected to transfer switch. I can actually hear the relays clicking though.
I will try another test tomorrow when my wife is not home. She hates it when the microwave clock blinks
No UPS has a 0ms switching time. It’s literally impossible by the laws of physics
The only way to do that would be to run the system off of battery all the time. I have heard that expensive APC units have a 5ms switching time. My cheaper(ish) units have a 8ms switching time.
I am not sure if 20ms will keep a PC up or not.
But this does not seem to be the issue. The issue that people are describing is the unit not turning the AC back on when utility power comes back online. This has nothing to do with the switching time.
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I think the slow switching time is one of the causes of the ac not coming back on when the power is restored. It surges and flips it back off again. I’ve been able to successfully (after the latest firmware) keep the ac on after a power outage, but only if the load is less than 1800watts. Before the firmware, it just kept it off no matter what the load. I’ve been trying to use the password to increase the grid charging amps, but it won’t stay for some reason. Since 1800watts is the 15amps, I thought maybe if I put the charging at 25amps (3kw) it might just keep the ac on (since the grid can fully feed the whole load). Btw, I’m using two ac300s in split phase (AC coming through L14-30r to the two AC300s. Ac1 is the x line and ac2 is the y, with the BLUETTI smart home panel). I’ve tested the phase with an oscilloscope and they are truly phased. If anyone knows how to change the max grid input current, let me know. I can get pass the password (by entering the password) but it won’t let me change the current (I’ve tried unplugging solar and grid charging before trying to change the setting). Thanks
Now support thinks the older AC300 may have a problem and wants me to do an RMA on it.
Will let you know how the next one works when I get it.
Now I will have one AC300 with 2200W input and no where to go .
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Yeah its fun being the beta testers.
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That’s my question too.