I just discovered a problem in my AC200P that I’ve had since late 2021. I’ve only used the unit during power outages maybe half a dozen times and it worked fine. I’ve also cycled it periodically as that is recommended, though I haven’t cycled it recently – it’s been about six months.
Today there was a power outage here so I tried to use my AC200P to power my refrigerator until the power came back on.
However, the AC200P isn’t working properly at all. When I last used it, I left the charge at about 90%. When I turned it on today, it read zero (0), and there was no power output. The utility power came back on quickly, so I tried charging up my AC200P with the brick charger. It began to charge – 1%… 2% – then jumped to 100%. So I tried powering my refrigerator and it started working, but the state of charge moved to 99%… 98% and then jumped to zero percent, with no power output.
I have now tried this same routine several times always with the same result. When charging from zero, it charges for a minute or so, 1%, 2%, then jumps to 100%. When discharging (running something), it starts at 100%, then 99%, 98%, then jumps to zero percent.
That’s all the unit will do. I checked the voltage of the individual cells. All of them read 3.37% except cell #2 which reads 2.80%. I have never seen this discrepancy before.
I’m not too happy about this expensive unit going bad after so little use, but with regular maintenance. The unit is in a good indoor place and has never been moved.
Does any one have any idea what’s going on? Is the unit, inexplicably, totally dead? Can it be revived? Any help would be much appreciated! Thank you.
The defective cell group (cell #2) is causing the BMS behavior you are experiencing (i.e. charging 1%…2% – then to 100% and vise versa for discharging). Likely your only option is repair, provided you repeated the recalibration process several times with no result. Sometimes you may need to repeat the re-calibration process 2-3 times for significantly imbalanced cells. If it exhibits the same behavior after several recalibration attempts, its a hardware issue/bad unit. It doesn’t matter if 15 of your 16 cell groups are good, it will behave according to the weakest member to protect the entire battery. Since they are all in parallel, the BMS can see 1 through 16. All for one and one for all.
Thank you sealy1986. I appreciate your response. I have also done a deep dive on the issue using various AI engines, and they all say essentially the same thing. I’ve tried recommended procedures for rebalancing the cells, but was warned that this probably wouldn’t work, and it didn’t.
Unfortunately, after very little use, this expensive unit is, for all practical purposes, dead. It can probably be repaired, but since it is out of warranty (according to Bluetti website) and a monster to pack and ship (besides the high cost of shipping, I would need to purchase packaging material and hire help to move the unit, plus the cost of the repair), it is not reasonable for me to try to get it repaired. It would cost at least several hundred dollars, and I would end up with a refurbished unit with no warranty.
From the AI research I learned that these LiFePO4 units are actually very fragile and subject to damage from many possible causes. When I bought the unit, I expected it to be more robust than it has turned out to be. And, I believe, for the price these units should be more robust and not so fragile and failure-prone.