B300S battery cell broken

Product Discussion Expansion Battery
1

Ladies and Gentlemen,
@BLUETTI
@BLUETTI_CARE

I’ve had a problem with one of my 4 batteries for a few weeks now.
I noticed it because the battery with ID 5 was at around 30% SOC of the AC500 at 1% or even went out. compared to the other batteries which had around 30%. (pictures available)
The setting is “PV priority” SOC 30%

After I looked at the cell voltage in the hidden menu, I noticed that cell 15 always differed from the rest. This was the case every time.
I have already completely discharged the battery twice (via the AC500). and then 1x with the AC500 and 1x with the power supply (D050). Unfortunately without success. The cell always has a lower volt value than the rest.

The deviations are:
08/26/2024 5 pm - AC500 by 59%, battery 5 by 56%, cells 15 - 3.26 V, all others 3.31 V
08/26/2024 11 pm – AC500 by 29%, battery 5 by 1%, cell 15 – 2.70 V, all others 3.30 V
08/28/2024 4 pm - AC500 by 99%, battery 5 by 99%, cell 15 - 3.29 V, all others 3.38-3.40V
09.09.2024 06 am - AC500 by 30%, battery 5 by 0%, cell 15 - 2.78 V, all others 3.28 V
09/14/2024 09 am - AC500 by 30%, battery 5 by 1%, cell 15 - 3.01 V, all others 3.29 V
09/14/2024 09 pm - AC500 by 99%, battery 5 by 99%, cell 15 - 3.33 V, all others 3.36 V
09/16/2024 01 pm - AC500 by 30%, battery 5 by 1%, cell 15 - 3.15 V, all others 3.30 V

Since calibrating didn’t help, I assume that a cell is defective and that’s why the voltage collapses at around 30%.

I am an Indiegogo Campaign supporter.

The software versions are:
IOT v9041.06
ARM v4048.04
DSP v4047.30
BMS all 4 B300s = v1022.09

Can you help me here?

Thank you in advance
Best regards

Johnny

1 Like
2

Hi @J0hnny

After calibrating, did you leave the B300S for a while on full charge, turned off?

Because thats when the Cells are starting to balance.

greetings
Erik

2 Likes
3

@Selfmadestrom
Normally when I recalibrate all 4 I discharge them all one after the other, turn them off and charge them all again.
During charging times the others are at 100%.
So normally I would say yes.
How long do the batteries have to be at 100% off?

1 Like
4

I would rest them about 1 day. If they balance correctly, the SoC of the machine shouldnt be 100% anymore.

2 Likes
5

Hi @J0hnny, I consider that this B300S battery is from a different batch than the others, which may result in slight voltage differences. To resolve this issue, we recommend disconnecting this B300S from the AC500 and calibrating it separately. Once this B300S, as well as the AC500 + 3 other B300S batteries set, are all charged to 100%, reconnect them together.
Please follow the steps below to recalibrate it:

  1. 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.
  2. 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.
Thank you for @Selfmadestrom’s kind help with this problem.

1 Like
6

Hallo @BLUETTI_CARE,

I let the battery discharge overnight and let it cool down for more than 3 hours. Then I disconnected all consumers from the AC500 and only charged this one battery until it was at 100%.
AC and DC were off.

September 24th 5:37pm - Start charging, SOC 0%, cell 15 at 2.86V and all others at 3.33V

5:47 p.m. already at 7%
Cell 15 3.30 V, all others 3.39 V

6:33 p.m., SOC 44%, cell 15 3.33 V, all others 3.50

6:47 p.m. 14 minutes later the battery was at 100%
Cell 15 3.30 V, all others 3.37

AC and DC on the AC 500 remain on off. Just the one battery.
Plugged in and set to standard UPS settings.

9:38pm, SOC 100%, cell 15 3.31V, all others 3.35V

Unfortunately the calibration didn’t help.
The jump from 44% to 100% alone was very unusual.
10-20% is ok, but 56% is a lot.

Unfortunately I think this is a defective cell.

Best regards
J0hnny

7

Hi @J0hnny, Regarding this issue, we are preparing to upgrade your BMS firmware to the latest version v1022.10, which should help resolve the problem.
Could you please provide the SN number of your AC500 so we can push the firmware?

After upgrading the firmware, please recalibrate again, as this will help restore the battery to its optimal state.

Additionally, could you capture a video or photos showing the SOC differences and the battery voltage issue? Please upload the video to Apple or Google Drive and share the link with us. This will help us confirm the problem.