Charging multiple B300 batteries

4 B300 Batteries being charged 3 show charge and 1 shows standby. Why?

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Hi @ShockerChan , Could you please provide a video or pictures when the B300s in charged? This will make it easier for us to find the problem quickly. Thank you very much for your cooperation and I look forward to your updates.

Why would you need a picture to understand my question. 4 B300 were connected. 3 showed charging 1 showed standby What would cause this? This morning I have 3 B300 batteries connected they have varying SOC 84%, 85%, 56%. They all indicate standby on the APP. Power is showing coming in from PV but all batteries show no charging. Why? why? why? why? why? why?

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I now have 1 B300 connected and have PV input. It now shows that it is no longer in standby but now indicates charge. That still does not explain why when more then 1 B300 is connected they all say standby. Unless it has something to do with the B300 having different states of charge? Charging these one at a time absolutely does not work for me. My next question is do all 4 B300 charge at the same time or is the charging power directed to lowest SOC B300 or Highest SOC B300 or just some random amount here and there?

Hi @ShockerChan , thanks for your confirmation.

B300 is the same charge and discharge. When charging, the charging power to the low SOC battery is divided more, and the charging power to the high SOC battery is divided less.
Connecting one B300 means that the charging power is all given to this battery pack, which will show charging. Connecting three B300s means the charging power is distributed to three B300s, each battery pack gets less charging power and will show standby, but is still charging.
As long as there is PV charging power on the screen indicates that all are charging the battery pack.

Hope that the above explanation can help you :blush:

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Good evening, I have 3 B300s connected to the Bluetti AC300.

My problem is that 2 B300s charge and discharge in an almost equal manner with 2 or 6% maximum difference, while one, the last one purchased, has a difference from the other two of even more than 20%, discharging before and charging after the others, and in addition it does not reach 100% but 99% compared to the others which reach 100%. I work in PV priority with 30% heat set. This also leads me to have the B300 number at 38 %, the B300 number 2 at 40 % and the B300 3 at 14 %. I wonder if this is a defect of the coach battery or not. I hope I can get an answer because I am doubtful whether to return it or not. Thank you.

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I am experiencing something similar. Long story short, the older battery (purchased in June 2022) discharges faster and charges slower which results in it being 30…40…or more percent lower than the newer battery. I have to disconnect the newer battery to allow the older one to catch up, then I plug the newer in and allow both to be used. Then when the sun goes down I disconnect the older one so it doesn’t get sucked dry. The main difference between the two batteries is that the BMS firmware on the older one is different (an older firmware, I would assume). When I go to the app to check for a firmware update on the older battery, it says there is no firmware update available. Either way, cumbersome. Not operating as advertised.

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@MontAnna, very annoying csa, unbearable to say the least for such an expensive system.
My situation is similar but the problem is not with the old batteries but with the new one.
Indeed the BMS of the two old ones carries older firmware than the new one.
I am not willing to do the cumbersome manoeuvres you are doing.
Haven’t you been supported by a warranty?
Bluetti doesn’t respond for this problem?

I’ve contacted Bluetti recently, just waiting to hear back. I’ll see what comes of it.

Hi @Alessandro @MontAnna , Sorry for inconvenience caused.
Can you try discharging all the batteries together to 0% and then fully charge them. The charging process cannot carry any equipment.

We suggest you try this first and then see if B300s still have this problem.
Thank you for your cooperation.

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Good news everyone. I discharged the 2 batteries together. There was a big disparity between the two right up until the last 10-20 minutes. Then the older battery hung out around 1% while the newer one drained to catch up. When I charged them up together (power outputs off) the greatest disparity was maybe 10% right around the half way charged point when they synced up again. I can give a report back in a day an report my findings after a little time has elapsed. I have done a little reading about how a BMS calculates a state of charge, and to be honest, there is no good way to do it. There are three ways to calculate SOC (as far as I can tell, read further if you’re bored, or you just need to know), each way has pros and cons…with battery storage, one will always run across one of those cons sooner or later.

Good morning @Bluetti Admin,

I also did the full discharge.
The last one I bought, which was at 11%, remained stationary compared to the other two which were discharging, then all three reached 10%, then they discharged in an almost synchronised manner with a difference of about 1-2% between them, and the newest one was always about 2% more discharged than the other two.
Then I connected the Grid socket and ‘having PV priority at 25 %’ it charged dini to 25 %. The next morning there was a shy sun that charged the batteries up to about 50% and there was a gap of about 5-7% maximum between the batteries.
Now the situation is as per the attached photo.
In your opinion, is it OK now?
Can I consider the batteries healthy?

Sorry for my apprehension but I have spent a lot on the system and I would like it to run perfectly.

I look forward to your feedback.

Best regards.

Hi @Alessandro , This is a normal phenomenon, please do not worry.
When using them, it is best to put the battery pack all to 0% before charging, and then charge all to 100% before discharging.

Just as a follow up. I have found that the displayed SOC for the two batteries indicates a greater discrepancy when it comes time to discharge. During discharge, one battery will appear to discharge faster (the one with the older firmware version). Also, and perhaps connected to the asynchronous discharge/charge, I have noticed that when charging via PV the battery with the older firmware lags behind significantly. If I plug in AC power to charge the batteries, all of a sudden, the battery with the older firmware starts charging really fast (or that’s what the SOC indicator tells me). Within 15 minutes or so, the two batteries SOC indicate they are synced.

After almost two weeks, the batteruies are nowhere near the same SOC according to the display. One is 10% and the other is in the 70 percentile range. I have contacted Bluetti, they have given me trouble-shooting directions. Charge to 100%, discharge to 0%, charge to 100% leave it sitting for a day turned off…switch cables, use one battery with the AC300 then switch to the other battery and use it (to see if the B300 batteries work normally individually).
I’m not complaining, but I will make an observation for those who are planning on using a unit or combination of units (I have an AC300 plus batteries and an AC200max). Thses units probably should not be used as a main power source off grid unless you have a back up because the situation will arise where you have to do calibration or trouble shoot a problem.
I like my Bluetti units, I will just say, there are some issues that will come up that should have been addressed or should have come to light during a beta test. If you’re OK with that, then Bluetti is for you. If you are not OK with that, you need to look at a DIY system or a different all-in-one system.

This morning I had the same situation where one B300 was on standby and the other three were charging from my 1.6 kW photovoltaic system. I had to disconnect one P090A cable to locate the series with the problem, then disconnect one B300 from the correct series to locate the exact battery. As I did that, I discovered that the lock switch on its P090A connector was not in place. Therefore, I reconnected all four batteries and confirmed that the connector locks were all in place. That reactivated the original B300 battery and all four are charging.

So, to everyone who have up to four B300 on their AC300 power station, please check and confirm the connector locks are all in place (two per B300).

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That is the most annoying question they ask. Can you send a video or photo? I had the same when I plugged in my ac300 and B300 for the first time and it went pop complete with a burning smell, but no external damage. And they said can we have a video??? It is an inanimate object it doesn’t sing, dance or jump up and down, but no they wanted a video of it sitting there doing nothing. The mind boggles.