Testing and experience with the AC300 UPS modes and parameters

Some of the UPS comments made in my prior recent postings before testing are corrected and clarified here.

I did some testing to learn about the different AC300 UPS modes and settings. Here are my findings, observations and understanding.

I do not have any solar or DC input connected to charge the AC300. I am only using Grid charging. So if there are any references of solar, it is only what the product panels or manual say or my understanding and not my experience or observation.

I did not observe any means to control when the AC300 would be able to stop powering the load by time of day. The Low SOC (State of charge) parameter, if available to be specified for that UPS mode, is the only parameter that can stop powering the load. When the battery state of charge depletes to the specified percentage, the inverter/AC output will be turned/cut off.

IE: setting the Low SOC at 20% directs the AC300 to turn off the AC inverter when the battery is depletes to 20% state of charge. As long as the AC inverter is on, (AC LOAD output switch) the load should be powered.

Other than option 1 Standard UPS, there are no references of the UPS directly powering the loads. Does that mean it only directly supplies power from the grid to AC loads through the AC mains in no other UPS options other than Option 1? And what does that really mean in regards to impact om the AC300?

UPS modes:

1). Standard UPS – The AC300 will draw power from the grid to run the load and will use the grid to maintain the battery state of charge to 100%. The screen panel refers to the term offline UPS. Offline UPS to me means the AC300 is not actively running on UPS battery backup mode and the UPS function is monitoring the Grid power and UPS is offline in standby mode. When in this state, the AC300 UPS directly supplies power from the grid to AC loads from the AC mains. To me, that means Grid power is being passed through from the AC mains to the loads bypassing the use of the inverter when the grid is up. It will use the battery to generate AC power using the inverter when the grid is unavailable. When the grid is unavailable, the battery will continue to handle the load until it depletes its state of charge to zero and shuts down.

2). Time Control UPS – There are 6 time intervals that are available. There is a reset function to clear out the 6 time intervals to 0 time frames. You may set each interval to a parameter of charge or discharge. Charge to me means use grid charge. Discharge to me means no grid charge. Discharge does not mean use batteries to discharge to the loads. So the term is not that intuitive.

You can set Low SOC and High SOC parameters.

Low SOC (state of charge) means when the battery depletes to this SOC level, turn off the AC Output/inverter.

High SOC means the grid charges the battery to this level. Then the rest is reserved for solar/DC charging. If the battery SOC falls below this level, grid charging will start. If there is no solar/DC input, the grid charge will not be used to charge the battery’s SOC beyond this level.

Observation: The priority of the time interval parameters take precedence over the High SOC parameter. For example, if the High SOC is at a level requiring grid charging but you are in a time interval of Discharge, grid charging not allowed, the grid power will not be used to charge. If you are at a HIGH SOC level that does not require grid charging but you are in a time interval set for Charge, then the grid power will be used to charge the battery until it is 100% charged. If the current time does not fall in any specified time interval, then the High SOC will determine whether to grid charge or not.

3). PV Priority UPS - only a SOC percentage parameter is used. No time intervals used. The percentage to me is the same meaning as the High SOC. The grid is used to charge the battery to this percentage and the rest is reserved for solar/DC charging. To me, this mode is a little ambiguous. Plus I don’t have solar so not much I can report here.

4). Custom UPS – There are settings to enable or disable Grid charging and/or Time control grid/no grid charging. Similar to the #2 Time Control UPS, there are 6 Time intervals and Low and High SOC settings. To me, using this mode instead of using Time Control UPS offers a quick way to turn off grid charging and or time control grid charging without the need to change the parameters.


Hi @t4602yf , thank you for a very thorough description. Did you manage to make the Battery SOC Low setting to work? In my case the unit won’t stop AC output upon reaching the level of charge set at SOC Low, continuing to drain the battery. I wonder if there’s a trick I’m missing.

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I use the ac300 only during grid outages which only happens very infrequently here. I switch over from grid power and exercise both of my ac300’s every month or 2. Only in single phase mode not split phase mode. My ac300’s are set on ups mode and not on soc mode. I do not have solar input and when the battery is depleted I charge it back up using the grid without ac output being on and with my transfer switch disconnected to prevent the ac300 from shorting. It’s been a while since i installed and tested the ac300. I no longer have a true good sense whether these parameters are working as described anymore. Sorry for the long winded response to say I don’t know.


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Bonjour Ă  tous / Hi everyone,
Un très bon résumé des différentes fonctions en mode UPS.

Je complète le point 3 (PV Priority UPS ) : la charge se fait prioritairement par les panneaux solaires tant qu’il y a du soleil et elle peut atteindre les 100% (quelque soit le pourcentage de charge de départ). S’il n’y a pas d’ensoleillement, la charge se réalise alors par le réseau électrique. C’est mon mode de fonctionnement prioritaire dans ma configuration actuelle AC300 + 4*B300.

A very good summary of the different functions in UPS mode.

I complete point 3 (PV Priority UPS): charging is done primarily by solar panels as long as there is sunshine and it can reach 100% (regardless of the starting charge percentage). If there is no sunshine, the load is then carried out by the grid. This is my priority operating mode in my current AC300 + 4*B300 configuration.

hello, I’m looking to use the time control function. I was wondering. if I use the time control function to discharge between 4pm to 8am (next morning) and charge from 8am to 4pm during when my electricity is lowest, is the A/C still ON (during the charging phase of 8am to 4pm) on the Bluetti for passthrough powering? For example, I want to connect my garage fridge and a separate full size freezer. During discharging, it would power on my appliances. During charging, does it still power up my appliances via passthrough? (based on your response, I think it’s a yes?) I just wanted to make sure what I am clear from your explanation before I purchase for my needs. Also, what happens if I only have charge from 8am-12pm, and discharge from 12pm to 4pm? What is my appliance doing between the hours of 4pm to 8am when I don’t have a time interval set? Is it powered by passthrough where it is pulling power from the grid through Bluetti? TIA

My AC500 is set up using PV Priority and it works great. It also makes it easy to raise the SOC in the app just by sliding the % bar. It was cloudy today so my AC500 didn’t get to recharge to 100% but lingered around 40%. There were thunderstorms and high winds in the forecast so I slide the bar up to 80%, just in case the storms caused a blackout (they didn’t, but you never know.)

St8kout, are you able to test the time control function for me? I don’t plan to use any PV for my system. Does discharge mean that it is powering the load from the battery and not grid? Also, during charging, is the load still powered on? If it is outside any of the time windows, does it act like a normal UPS where if there is a power outage it will power the load? TIA!!

@Spyris I run in Custom UPS mode with Time Control usually enabled. I can answer your questions about it.

Does discharge mean that it is powering the load from the battery and not grid?

Yes, the load is powered via the battery, grid input becomes 0W.

Also, during charging, is the load still powered on? If it is outside any of the time windows, does it act like a normal UPS where if there is a power outage it will power the load?

Yes, the load is always powered when running in the UPS modes while AC output is turned on. This is true if battery% is above the low SOC value you set. When running on “charge” time window, UPS functions still work. However, note the UPS switchover time is ~20ms compared to my APCs ~8ms. (If you are running split phase w/ 2 units, there will be an outage when power returns of ~5s, it doesn’t function as UPS but EPS :frowning_face: )

I noticed that too.
I set the lower SOC to 30%.
The batteries are discharged to 0% and the system switches off.
I have no idea how to make sense of using the lower SOC setting.
Maybe someone can explain it.
Apparently Bluetti doesn’t know how it works because the operating instructions are correct
definitely not with this setting.
I have the feeling that the whole AC300/500 concept is still in the user testing phase.