SOK Battery issues

[Y2JB]

Hi All,

I have a Growatt 5000ES which I have been running with a SOK 48V server rack battery (5kwh) quite happily for 6 months. I recently added a second identical SOK battery and i am now seeing some issues. The batteries are frequently not balanced and both charge and discharge at different rates (maybe this is normal?) and can vary in their state of charge by 20%. The problems manifest by the new batteries SOC frequently completely collapsing during discharge and jumping from around 40% to 0% instantly and then the battery and inverter both panic.

I am unsure if this is a battery balancing issue or if the new battery is faulty. One question i have is why is the new batteries BMS allowing itself to drain below 20%? This has resulted in the FCC going from 105ah to 91ah, which i assume is permanent damage!

I want to try balancing the batteries properly first. I asked about this before and was told to use the following settings:

Disconnect all comm cables
Set 05 to USE
Set 12 to 48.1
Set 13 to 55.2
Set 19 to 55.2
Set 20 to 55.1
Set 21 to 48

However on the growatt i cannot seem to set 21 to anything above 46.1 (which is clearly way too low for low voltage disconnect). Any advice on why i cannot set this setting and also more generally what i should do here?

Thanks!

 

[marionw]

First; download the SOKTool software that you can use to see the state of each battery and the individual cells in the battery

SOK Owner / Operator Manual: Chapter 4 – PC Communication (2022 Version) ~ Current Connected

NOTICE: This page only applies to batteries with a production date code of 2022-08. If you have a battery with a production code newer than this, please refer to the 2023 version instead. PC communication allows for Realtime monitoring of all information of up to 15 packs from one centralized...

www.currentconnected.com

Read the manual:

SK48V100 Server Rack Battery Owner & Operator's Manual | Current Connected

Full instruction manual for the SOK SK48V100 server rack battery. Everything you need to know is contained within this document!

www.currentconnected.com

Did you fully charge the batteries prior to placing them in use?
You need to charge the batteries to 90-95% then SLOWLY (by reducing charge voltage) charge the batteries until the BMS starts to balance the cells as indicated with the SOKTool software (the voltage for each cell will have a "BL" or "BAL" next to it when the BMS is balancing the cell). Once you do this the BMS will reset it's 100% SOC. Then you need to allow both batteries to balance with each other as well. This is easy to do and you can certainly request more help on this forum.

This is the cable I use to connect my computer to the Batteries RS232 port:

https://www.amazon.com/dp/B09P8D5WL9?ref=ppx_yo2ov_dt_b_product_details&th=1

 

[Y2JB]

I did fully charge them and they have been fully charged several times since. It just appears that the SOC rapidly drifts apart if I start to discharge the inverter (at maybe 3kw). After an hour or so they can easily be 20% apart.

You need to charge the batteries to 90-95% then SLOWLY (by reducing charge voltage) charge the batteries until the BMS starts to balance the cells

How can i do this? I depend on the Growatt to charge the batteries and have no control over the speed of charge. Do i just let them charge to 100% (via solar) then leave them to sit at 100% for a full day at 100% so they can balance?

Thanks for your help

 

[Gojay]

I did fully charge them and they have been fully charged several times since. It just appears that the SOC rapidly drifts apart if I start to discharge the inverter (at maybe 3kw). After an hour or so they can easily be 20% apart.



How can i do this? I depend on the Growatt to charge the batteries and have no control over the speed of charge. Do i just let them charge to 100% (via solar) then leave them to sit at 100% for a full day at 100% so they can balance?

Thanks for your help

Anything new with your system? Have you been able to get them to balance. Cell 5 in my pack 4 tends to drop to 2.7v when the rest of the cells is at about 3.2v. This has caused the system to shut down. Then the max I been able to charge this
Cell is up to about 3.37v.