SOC custom config not respected by system

I have a AC200L It is permanently hooked up to a 1K solar array. When the internal battery reach the lower SOC setting at 30%, the grid power kicks in and the AC200L does pass-trough to support the AC current drawn (works has attended). But no mater what is the upper SOC limit, it will never reach it trough one day (its winter time here in Quebec, Canada, so i dont get much sun). Its currently set to 80% but when the recharge from PV reach only 39%, the grid pass-trough will be cut off and the current drawn will be switch to the internal battery until its down to 30% and this cycle repeats everyday. Why the Bluetti app gives us a SOC config option but it is not respected by the system is a very strange behavior to me. The problem is either a poorly developed app or Bluetti fail to explain correctly to the customer how is SOC settings really works. Bluetti should address this ASAP. Anyone had similar experience or know more about this behavior ?

Hi @flomotion, We’d like to gather more information to help troubleshoot the issue.

Are you using Time Control UPS or Custom UPS mode? How have you configured it? Could you share a screenshot of your UPS settings?

Please note that if you’re using Time Control UPS, you’ll need to set not only the upper and lower SOC limits but also the charging and discharging time periods; otherwise, it won’t work as expected.

Additionally, please provide the SN number and current firmware version of your AC200L. We recommend upgrading to the latest firmware, as it includes improvements to the UPS functionality.

Hi @BLUETTI_CARE ! Thanks a lot for your fast follow up! Here is more details regarding my case:

-solar array is 1000W total, in serial, and is 24/7 connected to my PV input. Grid power is also connected 24/7.
-I have tried all UPS models except ‘Time Control’
-Custom mode will fall back to the internal battery before my high SOC limit is reach at 80% and that is even if PV is still coming in around 50 to 100W and this is with a schedule in place or not and charge from grid disabled.
-With the PV priority mode, i set it to 30% SOC and yesterday when battery was up to 39% and charging only from PV, it switched back to battery power and cut off the grid pass trough.
-I have attach some screenshots but i will only share my serial number via private email.

I am located in northern Canada, Quebec and during this time of the year, there is not much PV charging going on everyday. The most i can get is around 10% gain a day with my 1000W solar panel array. I wish there was a way to at least be able to set the AC200L so it can do a AC pass trough when the battery reach 30% and stop the pass trough at 80% but to only recharge from the PV input until the internal battery reach 80% (even if this recharge method take up a few days). Is this possible ? The SOC settings would suggest it could but its not working so far. Thanks a lot for your help!!


It sounds like an issue with either the app’s configuration or how the system interprets the SOC settings. I would recommend reaching out to Bluetti’s support team for clarification, as it seems like the app may not be syncing properly with the device’s behavior. Hopefully, they can address this and provide more detailed guidance on the SOC settings.

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Hi @flomotion, We noticed that you have set a custom UPS mode with a minimum value of 30% and a maximum value of 80%.

This means that when the AC200L’s battery level drops below 30%, grid charging will be activated to maintain the minimum battery level. At the minimum level + 10% (i.e., 30% + 10%), the system operates in grid bypass mode to support the load. Once the SOC exceeds the minimum retention level + 10%, it switches back to battery-powered mode.

This appears to be functioning as expected. This mode helps maximize the use of solar power rather than relying on grid power.

@BLUETTI_CARE Thanks for the clarification, SOC makes a lot more sense now. This behavior should be listed somewhere in the app or on your website and even in the manual. I still have some questions for you regarding this. Since my solar array is not very productive here at this time of the year, i figure it would be better to just keep my AC200L top-off around 80 to 90% for power outage only and do a discharge maybe once or twice during the winter for battery maintenance. What i would like to do is to have my solar array charging the AC200L up to around 90% BUT while its getting there, i would like the AC200L to support the current load with the grid bypass mode all the way and not stop at my low SOC limit 30% +10%. The problem that arise when its switching back to the battery at 30%+10% is that i cant charge the battery with ONLY SOLAR because my solar on most days will bring up the battery to around 42% and then the grid bypass mode turns off and my battery can never reach my top SOC setting at 90%. What would be the best practice to get to this routine going and/or is that even possible with the current AC200L design ? Thank you so much for the support!

Hi @flomotion, Thank you for your suggestion.
We recommend setting the PV Priority Mode and adjusting the SOC to 90%.
This should meet your requirements.

@BLUETTI_CARE i just tried the PV Priority mode again but it not very practical. I did set the SOC at 81% this time and let it roll for a few days. What i noticed is that on one day, my solar was producing 500w for a hour and battery level was at 81% and grid pass thru was active as normal. It then when up to 88% after a few minutes without pass-thru and then grid power took over and recharged the battery to 100%. It doesn’t make sens at all ! So i put it back to Custom mode and set my SOC to low 80% and high 81%. If i get this right, when battery is going to hit 80% pass thru will be activated and when solar is available, ONLY solar will recharge over 81% to 100%. Can you confirm that this should be the behavior of my custom config ? Thanks!

@BLUETTI_CARE : Another update regarding my observation of the system: My SOC for the CustomUPS are set at LOW:80% HIGH:81%. I just notice that while battery was depleting at 84%, the grid pass-thru kicked in. Why is that ? isn’t the grid pass-thru should kick-in at 80% ? Now 1 hour later (see screenshot where battery is at 83%), the pass-thru is off and power is now pulled from the battery to support the load. No modifications have been done to any configurations during all this time. Why is the behavior so unpredictable like this ? No mater what settings i am using, nothing seems to make sense


! See screenshots for my settings, schedule is at off-peak during those screenshots. Thanks a lot for your help.

Hi @flomotion, Generally, when PV Priority is set, AC charging will stop once the SOC reaches the configured value.

Regarding the Custom UPS, this behavior is likely related to the SOC hysteresis value, which is normal. When an upper limit is set, it typically triggers only after exceeding the set value by a few percentage points. Similarly, for the lower limit, the trigger occurs only after dropping a few percentage points below the set value.
I hope it does help.

@BLUETTI_CARE My SOC for PV priority was set at 81% so if i follow your explanation, grid charging should have happen until 81% +/- 10%. Thats not what happened, the battery was recharge to 100% using grid power. How can this be ?

Regarding CustomUPS, i understand that set SOC value are not precisely being respected. That being said, why once pass-thru was activated at 88% (low SOC set to 80%) why it (pass-thru) went off at 83% and came back in effect under 80% ? why the on and off juggling like this over my set SOC low level when it should only come in effect UNDER my low SOC setting ? Can i suggest one thing to your DEV team that would simplify the customization and understanding of it? Why not having ONLY a one page ‘Working Mode’ Custom setting for the device (SOC) and having it all in there : SOC (low, high), time of use, charge from grid switch. After all, PVPriority by logic should only charge from PV but it is not and i have to go to CustomUPS so i can disengage the ‘charge from grid’ switch to make sure its not taking grid power to recharge. I would also add a on/off switch in there to control the pass-thru so i can decide if and when i want to use pass-thru and bypass the automatic switch to pass-thru that is using a very obscure algorithm. Thanks for your follow up!

Hi @flomotion, Thank you for your suggestion, we have already forwarded your feedback to the development team.


Based on your description, setting the SOC to 80% under PV Priority Mode and having the grid charge to 100% does indeed seem problematic.


Could you try resetting the settings and confirm whether this issue occurs without any solar input during the process? Does the grid still charge to 100%?


If there is solar input during this process, the grid should stop charging at 80%, while solar charging continues.

Hello flomotion:
I use my AC200L battery entirely as a standalone unit, not connected to the grid at all.
My batteries working mode is set to PV PRIORITY UPS with the SOC setting at 25% (I keep it set lowish as it won’t be coming on anyway because I am not connected to the grid)
Charging mode STANDARD
I am a fellow Canadian living not far from Quebec, so I know it has been difficult lately to acquire sufficient solar power to keep my devices/appliances going.
I am also using considerably more panel power than you said you were using at the moment, and have had to reduce my AC load and sometimes lately just disconnect all devices altogether due to lack of sunshine.
I hope this helps you a little.
The winter solstice is coming Dec 21 4:21 am. Then our days start getting longer again, hooray.
B