Abnormal and unequal behaviour between several B300 batteries with AC300

Good morning,
I am writing this post in the hope of finding out if the behaviour of my recently purchased battery is normal or not.
I own an AC300 with 3 B300 batteries, the last one was taken about 3 months after the other 2.
Unfortunately the last battery arrived with a heavily damaged packaging, banged to with a hole symptom of mistreatment suffered during transport which alarmed me, the battery has no obvious damage on the shell.
In agreement with the seller (the only battery not bought from the BLUETTI store) I activated the battery, installed it and immediately showed a difference on charging and discharging compared to the other 2, not charging at 100% but 99%, discharging faster and charging more slowly.
Suggested by a Bluetti technician in this blog, I charged at 100% and discharged 100% to try to synchronise the batteries and at first it worked then after 1 week we were back to the same as before with charge differences between the first 2 of over 20%.
Bluetti started to tell the commercial broker that they were willing to collect the battery to check the condition and decide whether to repair, replace or declare the battery compliant.
I have noticed that the BMS firmware of the latest battery is new compared to the 2 previous ones that are 3 months older, but even when I request an update it tells me that there are no updates available.
I want to point out that the last battery, the one giving problems is connected to the 2nd battery and not directly to the Bluetti.
The Bluetti works in PV priority at 25%.
My question is:

  1. is a difference between the first 2 batteries of 20-40% on discharge and charge normal?
  2. can the different firmware compared to the other 2 lead to this problem or is it really defective?
  3. bearing in mind that it always charges slower and discharges faster than the other 2, does this behaviour adversely affect the other 2 batteries over time by deteriorating the first 2 before time?
  4. If I decide to return the battery for repair (if it is really broken) how soon would I receive the product?

I use the Bluetti as my home backup system and I absolutely need 3 batteries because with 2 I can’t manage the house, staying uncovered for months is not contemplated for me given Europe’s energy problems.

I hope some good technician will give me the tips I need because I am a mechanical engineer and not an electronic one…

Best regards.

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I’m not sure if it’s normal, but my batteries do the same thing. I bought the AC300 and one B300 battery directly from Bluetti, and then bought a 2nd B300 from Lowes a month later. The battery firmware numbers are different, both are up to date per app, and the newer battery is always at lower SOC. Did charge / discharge calibration, but if I do not have enough solar to get to 100 % every couple days the batteries drift apart again.

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I have one AC300 and 2 B300 batteries, all from Bluetti. The newer battery (which has a later series firmware) always has a higher charge. I am working with Bluetti customer service to try and figure out whether this is due to the AC300 or the B300. The difference between the two can get quite extreme…one will be around 10% and the other around 70%. They gave me an extensive troubleshooting list which I’m working through.


Hi @Alessandro , Please don’t worry, there will be no damage to the battery packs. However, in order to keep the SOC difference between battery packs not too big, we suggest you try to keep all battery packs empty when you use them before charging.

Good morning,

Are you telling me that Bluetti functions such as PV priority mode cannot be used?
Are you admitting that the Bluetti is an expensive toy?
Honestly, after spending all this money for believing in BLUETTI by buying AC300 + 3 B300 batteries PV panels and interface to the home system, I expect the machine to run perfectly. My house now depends on the Bluetti AC300 and if it is not reliable then I have made a bad purchase.
So far I have not had any answers to the questions posted except for one, namely that you don’t drain the batteries.
Discharging all the batteries means blowing out the power in the house. If I chose PV priority mode and boetche I have to have an electronic reserve for the constant blackouts I have in my area.
The high-efficiency steerable photovoltaic that I have specially built yields 10 kWh in December in 6 hours, so I would have to buy another battery pack, but if this is the case I avoid spending any more money.
I hope you can answer all the points posted so that I can understand if I can pass on recommending and building this system for other friends as well.
Best regards.

Exactly the opposite of my case.
By any chance is the firmware of the batteries the same as mine?
What mode are you using the Bluetti AC300 in?
Have you always connected the PV and Grid power?

Exactly the same thing happens to me as well, it would be important to understand why they don’t even out the firmware with an update, maybe that would solve the problem.
I’ve been trying to update every day but nothing…

These are the firmware numbers, I’ll post them

with a photo

The older battery (the one I bought a few months ago) has BMS version 1014.10. The newer battery (the one I bought last month) has BMS version 1024.03. Something I have noticed is that the AC300 seems to prioritize charging the battery with the lower voltage. I find the voltage on the newer B300 (BMS version 1024.03) is usually lower even though the displayed SOC is higher. The voltage on the older battery is usually higher even though the displayed SOC is lower. I am no battery expert, but I was under the impression that the BMS calculated SOC based on voltage. The higher the voltage the higher the estimated SOC.
I almost always charge via PV. No grid connection.

Something to add to this. I discovered (by accident) that if the battery that is slower to charge happens to have a greater SOC (say, for example, if I disconnect the B300 that is always low and wait for the B300 that is always high to get drained then hook the always-lower-B300, the unit starts pulling power from the always-lower-B300 to feed that power to the always-higher-B300). I am thinking more and more that the SOC imbalance is caused by the voltage reading from the battery. Maybe the problem is purely the SOC indicator, but this would drive me back to an original point I made in another thread. If the SOC indicator is so inaccurate as to read in the 20 percentile range when it is actually in the 80 percentile range, it’s meaningless.

Good evening, if you remember I had the same problem as you.
My system is 75% powered by the solar panel and has a 25% power reserve.
I have 3 B300 batteries, 1 with a different firmware to the other 2. I can confirm that after 3.5 months they have stabilised and have no more than 2 % difference when discharging and no more than 10 % when charging. I have a 2,150 kWh photovoltaic system which is oriented according to the seasons, and for 2 weeks I have already touched the production of 10 kWh per day. Right now I am in backup and tomorrow the solar production will start again and I will not have taken anything from the grid, so I am self-sufficient. The test was successful and fortunately my calculations were correct. If I can’t get all the power produced by March, I will buy the last battery pack for a total of 4 B300.
All this explanation to say that I am using the Bluetti AC300 + 3 B300 as my main source finally successfully. More if they finally update the BMS firmware I will let you know.
Have a good evening.

P.S. from what I understand but am not entirely sure, the difference in ‘SOC’ is CHIPs from different manufacturers but the firmware is the same.

Have a nice evening.