Which is more accurate?

This is something new.
I have 6 B300s batteries.
I know about doing battery calibrations and all that, and one of the batteries is always 15-20% below the other 5, until they all get charged to 100%. But now, the low one (“pack 1” on the APP) never reaches 100% anymore. It goes into STANDBY at 84% and stays there.
Normally when one battery is low, I can look at the 5 green lights and see which one has only 4 lights, but now they all show 5 lights (even though the APP still shows one is 84%.) so I don’t know which battery to calibrate.
So which is more accurate, the APP or the 5 green lights on the batteries?

If the battery is below 100% and shown as “standby” it means the current is not going either direction from it, that means it’s not discharging and the system is not receiving enough current for charging.
At the moment you saw the battery at 84% and in standby state, from which source you were providing charging power?
With 6 packs and PV input only I’m not expecting it to charge if solar power is below 100 W (value that depends on many factors i.e. AC/DC enabled or not), in that case PV power is used to maintain the system and is not enough to also get stored, which result in the batteries staying in a standby status.
About a 84% SoC showing as 5 green dots on the battery for me that’s normal since 5 green dots equals to SoC >80% but I’m not sure if that also depends on the firmware version. Anyway green dots and App charge levels are using both the exact same SoC information from the BMS via Modbus and MQTT and they don’t differ.
Anyway, you should imagine all the batteries connected in parallel to the same bus, and drawing or providing current on demand by maintaining the nominal voltage on the bus itself. Hence, you don’t need to know which battery to calibrate it since by providing input current to the main unit and so positive current on the bus, the battery which has the lowest voltage should calibrate by itself. That is better to be done by AC input instead of PV input since solar couldn’t always provide enough current to complete calibration, depending on its scale and daily irradiation. AC input instead, even at very low current, always provide a constant positive current on the bus to complete calibration to 100% in any case.

I use the system 24/7 using PV Priority Mode. I have enough panels to fully recharge them to 100% before Noon everyday. They stay at 100% until around 4 or 5pm.
Normally, they would all show 100%. What’s different now is that this one battery won’t go higher than 84% no matter what. I even tried swapping the cabling around.
As for cabling, I have 3 batteries on each of the two inputs of the AC500.
What can be done about this one battery that won’t go higher than 84%? Plus it’s always lagging behind the other 5 when recharging. Even now it’s at 29% while the other 5 are around 50%. (It’s 10am here and a bit cloudy, but I expect the other 5 will be at 100% in maybe 3 hours.)

Now I can see the “problem” battery because it has only 1 green light (with 4 flashing) while all the other ones have 2 green lights (with 3 flashing). It’s the last battery I added to the system this past November. I know it’s the newest one because it’s the only B300s with a “Caution” sticker on top that the others don’t have.

I sometimes have this same problem with a b230. If you have a Bluetti AC-DC adapter (t500 or t400) you can try this: disconnect the B300s battery which has the problem and charge it alone with the AC-DC adapter until it is full (the AC-DC adapter light turns green), then reconnect your B300s with the other b300s/ac500 and see if there is any improvement!

I was going to try that tonight when the sun goes down and I can shut the whole system off. I don’t know if I can unplug a battery while it’s running so better safe than sorry. And to turn it off they make you unplug all PV inputs, unless it’s dark outside. So I’ll just wait a few hours.

Update, now that same battery is stuck at 77% in STANDBY while the other 5 are at 100%. Seems to be getting worse. Funny how this is the newest and latest battery I added to get to six.
Also, it now only has 4 steady green lights and the 5th light is off; no flashing?!?
Okay, I used the T500 to recharge it to 100% and plugged it back in to the battery bank. All batteries are in discharge mode now that the sun has gone down. I hope this does the trick and they all go back to 100% tomorrow.

On a side note, Vegas is having multiple power outages lately all around the city. What’s nice is I only find out about it in the news.
I have no idea if my neighborhood has had an outage😛

With 6 B300s (you broke the records!) and I imagine the quantity of panels that go with them, you can certainly also power your neighbors!

Update May 16:
After fully charging that battery with the t500, I added it back to the battery bank, and within 6 hours it had already fallen below the SOC of the other 5 batteries, even though all of them are in “Discharge” mode.
It’s 11:30am the next morning and it’s down 10% from the others. I think it’s time to contact tech support about it as I don’t think it has the same capacity as the other B300s.

I think Bluetti will ask you first to do a complete recharge and discharge cycle to recalibrate the Soc:
-Charge your faulty b300s to 100% (b300s alone, with the T500) = the LED of the adapter changes from red to green.
-discharge the B300s (alone) until the automatic extinction of your faulty b300s (for example via the usb C socket or the 12v cigarette port with an appliance)
-Recharge again your b300s to 100% (alone, with the T500)
-Reconnect it to your ac500/others b300s and see!

Explanation here :

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I did the calibration last night and used the t500 to recharge it (took almost 8 hours; I don’t think the t500 is putting out 500W, but somewhere around 300W.)

I emailed support and they wanted all the usual info. They also said to do the calibration but to also let the battery sit for a day while OFF. I never heard of doing that, so I’m waiting to hear back. They wanted my shipping address so it sounds like they might be replacing it. (There goes my back, packing the old and unpacking the new.)

Interesting indeed. The outcome is near!