I have an AC200MAX connected to 2 B300 Batteries. Each battery is connected directly to the AC200MAX. These are all normally charged at 100% and waiting to be used for backup power during an outage. Today I started my 6 month maintenance drain to bring all three devices down to 20% SOC. I got the overall SOC to about 28% so far. However, when I look at the individual SOC values, the AC200MAX is at 15% and the 2 B300 batteries are both about 35%. I am only using the AC output from the AC200MAX to run circuits in my house. What is going to happen when I continue to discharge the batteries? If I continue my discharge, will the AC200MAX get to 0% SOC and shut down even if the B300s still have 20% SOC? Or, will the AC200MAX keep running off the B300s even when its own SOC gets very low? I don’t want to hurt the AC200MAX batteries with very low SOC while bringing the B300s down to 20%. Please let me know what is supposed to happen. Also, I am not providing any PV or AC charging in order to bring the batteries down. Then, I’ll charge them all back up with my panels. Thanks in advance!
Your AC200Max won’t reach 0%. On my AC200L, there is a similar unevenness of SOC, but when the AC200L reaches 2%, it draws on the expansion batteries a lot more until the expansion batteries also reach 2%.
Thanks for the info!
I hope @BLUETTI_CARE chimes in and says what it’s supposed to do. Seems like it shouldn’t go below 20% SOC until the expansion batteries are at the same level.
Hi @clseaman, Please rest assured, @aaron33’s opinion is correct.
You can discharge the AC200MAX, and the B300 will provide power to the AC200MAX. The SOC of the AC200MAX and B300 will maintain a dynamic balance. While there may be some differences in their charge levels, the battery management system will strive to keep them relatively balanced.
However, if the difference becomes too large, we recommend updating the BMS firmware and calibrating the batteries separately. Afterward, connect them together when both are at 100% charge.
Please follow the steps below to recalibrate it:
- Please discharge all the power (charge AC & DC appliances with the power station) until the SOC is 0%, turn off the machine, and leave it for 3 hours till it cools down.
- Please charge it again, please do not load any device when charging it, and do not interrupt it while in charge.
You can click this link for reference.
Please let us know if it does help.
Thanks for the info @BLUETTI_CARE.
Does recalibration provide any improved performance or efficiency, or does it simply allow the SOC values to stay closer together? In other words, does recalibration really do anything useful besides get the SOC numbers to look better?
Hi @clseaman, Recalibration is indeed very helpful. The machine uses complex calculations to determine the accurate battery level. Each recalibration resets the system and recalculates the values.
Over time, the State of Charge (SOC) value can gradually deviate from the actual value. When the machine believes its battery is at 100% while it is actually at 80%, it won’t continue charging, and the remaining 20% won’t be used. Therefore, we recommend recalibrating every three months. However, if you find that your machine is operating normally and there is no issue with rapid power depletion, recalibration may not be necessary.
Additionally, to maintain SOC balance between the AC200MAX and B300, it’s best to ensure they are closely matched before connecting them together. This helps in keeping their SOC values more aligned.