Your modules are most likely unbalanced.

That means the SOC of one module is higher or lower than SOC of other ones.

Did you ever expand the battery by adding more modules?

If yes, this could be the consequence of not following the right procedure for expansion.

If no, then this is just a consequence of long term battery use without proper balancing.

Because all modules are effectively wired in series, your usable capacity is reduced, if one module is out of balance.

If one of the modules is at 100%, while the other is for instance at 85%, that means you loose 15% capacity "at the top". And then when you discharge the second module will be at 10% while first one is at 25%.

You can check the cell voltage data on Cloud, to see what is the voltage difference at 100% and when battery hits 10% SOC. 

To fix this you can disassemble the battery and use a DC charger to "top up" all modules to same voltage. For instance, if you charge all the modules to 108V-109V, you should be quite close to 99-100% on all modules. But you must wait until charging current drops down to 0A at 109V.

Don't charge higher as you might overcharge the cells.

But that is usually not a permanent solution.

Write to Deye support, tell them that they should install firmware that enables modules balancing.

They usually do not want to do it right away (I don't know why), but that firmware is only thing that will prevent this from happening again, and should be installed on all GB-L batteries sooner or later... otherwise we will have much more problems like this very soon.

@tribesman So that means they have a separate piece of software that can be installed for such cases, independent of the current battery firmware MCU3_HVCUE16XXXXXXXX.bin?

Write to Deye support, tell them that they should install firmware that enables modules balancing.

Yes, there is a specific version of FW that enables module balancing.
But it works in a peculiar way. It does not balance while the battery is sitting at 100%.
You need to cycle the battery for balancing to work...

Don't ask me why is that... or why is that FW not a "standard issue".

@tribesman Can you provide information about a version number?

@tribesman That’s complete nonsense you’re talking. I’ve been in touch with DEYE—there is no separate software that does this. Why are you spreading such rubbish here? If this software really exists, then name it clearly and specifically.

I guess this does not exist... fine then 🙂

Ask Deye support why are they unwilling to install this FW as a "standard issue".
It is available for weeks now, but you have to argue with them and if you want to get it installed. ¯\_(ツ)_/¯

It just the way this company works.

And it is really not nice of you to accuse me of talking nonsense, when you obviously have limited knowledge about the issue and no direct contact with Deye engineers.

Ich habe ein ähnliches Problem. Mir hat der DEYE Support mitgeteilt das mein Batteriemodul 4 von 5 Batteriemodulen von der Spannung abweicht. 

If it still appears abnormal, we will arrange to send it to a service center in Germany for inspection and voltage balancing, as I found on the platform that the voltage of the fourth pack is lower than that of the other packs.

Ehrlich gesagt habe ich keine Lust, die komplette Batterie einzuschicken. Könnte es eventuell etwas bringen, zunächst den gesamten Akku auf 100 % SOC zu laden, dann das betroffene Modul – in meinem Fall Modul 4 – auszubauen, die verbleibenden Module auf etwa 90–95 % SOC zu entladen, anschließend wieder vollständig auf 100 % SOC aufzuladen und danach Modul 4 wieder einzusetzen? Hat jemand mit den DEYE‑GB‑L‑Batterien Erfahrung damit oder diesen Ablauf schon einmal durchgeführt?

This is common fault in GB-L, a consequence of poor balancing strategy in BMS.

You can charge the battery to 100%, disassemble the modules, measure voltage of each module, and then charge each module so it it topped up to 110V.

Then reassemble it back together, and press "clear relay adhesion" in the menu for at least 3 times.

Then restart the battery and repeat charge-discharge cycle.

It might help, but it is not a permanent solution.

@tribesman I unfortunately don’t have the equipment to charge the packs individually. The voltage needs to be at least 160 volts, which means I would always have to use two modules to carry out the process.

Hello,

a guide  how to charge the modules seperatly you can find here: https://dy-support.org/community/anleitungen-tutorials/gb-lm4-0-hochvolt-batteriepflege/

@mrwoofa Das habe ich schon alles gesehen aber das traue ich mir nicht zu um ehrlich zu sein.

Thank you for your Information. What is the permanent Solution?

@tribesman Thank you for your Information. What is the permanent Solution?

Go to the Installer of that High Voltage System and complain.

And if YOU are the installer.. try the next time a low Voltage system.