AC200P cell 15 problem

Product Discussion BLUETTI AC Series
1

My sogen will charge from 0 to 100% on the wall charger in less than 2 hours. Running a 60w ac load (fan) it dropped from 100 to 0 in less than 2 hours. Cell 15 voltage is at 2.6 V at this time while the rest of the cells are 3.31V or close to it. I have tried calibrating the BMS multiple times thinking that was the issue but now see the problem as most likely a bad cell. Is there anything I can do for this

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other than try to replace a cell. I have had the unit for several years, but it really only gets used in my camper van once a year for 5-6 weeks to run LED lights, charge electronic devices and runs dometic fridge freezer with a roughly 55-60W load. Attached is picture of BMS at 0 percent

2

I understand that at 0% cell #15 is at 2.61 V as the picture is showing. That means that the BMS stopped discharging because that cell got an undervoltage situation.
Could you please charge the device and take a pic at the same screen at the exact moment the unit goes from 99% to 100%?
I would like to know the voltage of cell #15 when the unit reach the maximum charging voltage to understand if it’s just unbalanced or if it has a charge capacity different from the other cells.

3

Hi @Heritage, Based on the information you provided, the voltage difference is indeed quite high. It seems that the only solution now is to contact customer service for repair. Please contact the U.S. support team at service@bluettipower.com.
We suppose that the issue is due to incorrect battery storage.
Here are some suggestions for storing the unit.

  1. Never store the battery empty, even for only a few days. LiFePO4 batteries might be unrecoverable if stored empty.
  2. Storage temperature: 0-40℃. Don’t let store the battery in a humid environment. Keep it away from fire as well.
  3. The optimal state of charge for long-term storage is 50%.
  4. The battery will slowly self-discharge over time. The battery should be recharged every 3-6 months.
  5. Don’t store the battery on its side. Keep it up straight.
  6. Don’t stack things on top of the unit. Don’t block the fan.

Thank you, @ndwr, for your help and troubleshooting.