AC Open Relay Circuit

Hi Everyone,

Today we’re experiencing a few power outages at my home due to a snow storm. I have two AC300’s; one AC300 is running a 220watt load and another AC300 is running 4 freezers that can average 150watts to 600watts.

The AC300 that is running the freezers is receiving a 026 error (AC Open Relay Circuit). I’m not sure if this is at the time of the grid power outage or if it’s when the grid returns. The other AC300 isn’t experiencing any issues.

I’m suspecting that the error is related to the load on this AC300… Now the AC300 should be able to handle the running load of 150-600 watts. However when the freezers get initial power they can spike up to 2200 watts for all 4 freezers. So since this is below what the AC300 is capable of I’m now thinking it’s the Grid AC Input setting that I have… I had it set to 2Amps to trickle charge the battery… but I’m suspecting that I might have to set this to the startup requirements of my loads.

Thoughts? Or has anyone else experienced this issue?


4 freezers starting up at the same time can easily exceed 3000w as they surge, the surge power for a freezer can be 10x the running watts. If they are all locked and start at the same time, then it can exceed the AC300 surge. It says 6000w surge, but that is for a fraction of a second. Useful surge of a few seconds is around 4500w. It can handle overload to 3750W for up to 2 minutes.

Try to start 1 freezer at a time by unplugging them all and then plugging one in at a time, it would probably work that way.

Also, why trickle charge, if you set it to say 12A, it would stop charging once it is done right? Actually how do you set AC charge amps to less than 10A?

I actually have smart meters on my electrical lines, so I know that it’s exactly 2200 watts for all 4 freezers to fire up at the same time and that’s well within the ability of the AC300.

In short, I figure this out… the grid line for my AC300 has a GFCI outlet on it. I used this outlet to simulate a power outages and was able to duplicate the issue. As I suspected, the AC300 appears to try to match the incoming grid amps to the load on the AC300 when grid power is initially returned and it throws a “AC Open Relay Circuit” when when I have it set to 2amps charging.

When I bumped the charging to AC input to 15amps the problem does not occur… This may be a bug or by design. I will need to check with Bluetti.

I had it set to charge at 2 amps because I didn’t want the grid to charge the battery too quickly. On the AC300 menu (on unit) you can set the AC Input amperage from 1-15amp. You can also set it to 15-30amp, but you need a passcode from Bluetti to enable anything higher than 15amps.