Hi,

I have had many problem of Over Voltage and after replace new batteries I tried to monitor the situation.

I see that during the charge/discharge cycles the SOC values of the batteries are never the same SOC values but there is often a difference of 7/10%:

I would like to understand if it is normal for the batteries to have a different SOC value even if the cells voltage are identical?

The system consists of 6 US2000C pylontech batteries.

Does this behavior happen to you too?

Is there a way via commands sent to the battery to have a soc value corresponding to the voltage value?

Thank you in advance

 

 

1 hour ago, Matteo_Mantovani said:

I see that during the charge/discharge cycles the SOC values of the batteries are never the same SOC values but there is often a difference of 7/10%:

I would like to understand if it is normal for the batteries to have a different SOC value even if the cells voltage are identical?

Is there a way via commands sent to the battery to have a soc value corresponding to the voltage value?

They will vary. It can be dependent upon a number of factors, eg ages of the batteries, how they are wired, etc.

Your batteries SOC will be a lot more accurate than any voltage values due to the voltage curve of the battery.

I wouldn't worry.

Edited November 15, 20241 yr by Tinbum

Are these batteries all exactly the same age?  The reason for asking is that the cycle counts are very different.

If they are the same age it could be due to unequal cable lengths.  Are they connected correctly - positive and negative at opposite ends of the pack?

I run 10 pylons and never see difference like these....

2 hours ago, Matteo_Mantovani said:

 

Is there a way via commands sent to the battery to have a soc value corresponding to the voltage value?

 

 

Thank you in advance

 

 

As the load affects the voltage and further depending on how the 6 batteries share the real time load the voltage could be very different even at the same SOC. Thus not a method that means much. 

Earlier replies indicate some reasons for the 7-10% difference. 7% not easy to detect with voltage. 

1 hour ago, Calvin said:

Are these batteries all exactly the same age?  The reason for asking is that the cycle counts are very different.

If they are the same age it could be due to unequal cable lengths.  Are they connected correctly - positive and negative at opposite ends of the pack?

I run 10 pylons and never see difference like these....

no the battery have different age and also different fimware:

Battery 1: FW V2.2 new chip ( age 1 month)

Battery 2: FW V2.2 new chip ( age 1 month)

Battery 3:  FW V2.2 new chip ( age 1 month)

Battery 4:  FW V2.8 old chip ( age 2 years )

Battery 5: FW V2.8 old chip ( age 2 years )

Battery 6:  FW V1.8 new chip ( age 5 month)

 

The master have positive connected to the inverter +

Tha last battery (n°6) have negative connected to the inverter -

 

I try also to maintain the batteries connected toghether but not connected to the inverter for 6 hours to have a idle situation.

When batteries reach the idle status I check the SOC but was different.

 

Also I've seem that that this SOC differece non remain every time the same but in same case the different is 1-2%, specially in the evening when no big load or solar are present.

 

 

 

 

 

 

The SOC follow the ages nearly perfectly. Pack 2 is very slightly different.

Edited November 15, 20241 yr by Tinbum

44 minutes ago, Scorp007 said:

As the load affects the voltage and further depending on how the 6 batteries share the real time load the voltage could be very different even at the same SOC. Thus not a method that means much. 

Earlier replies indicate some reasons for the 7-10% difference. 7% not easy to detect with voltage. 

Since the last 3 batteries had the procedure from a technician to clear the EEPROM (to reset the fault).

After the reset I saw that the SOC was changed immediately (about 10%) and the technician told me that the correspondence of voltage and SOC is back to normal

 

For example today I have had:

The max difference happen during the charge

Edited November 15, 20241 yr by Matteo_Mantovani

4 minutes ago, Matteo_Mantovani said:

For example today I have had:

The max difference happen during the charge

It really isn't a problem.

sometimes I find in the early morning, after the night discharge, a situation with unbalanced batteries and some batteries well below 20%:

Could it be a problem?

7 minutes ago, Matteo_Mantovani said:

sometimes I find in the early morning, after the night discharge, a situation with unbalanced batteries and some batteries well below 20%:

Could it be a problem?

Batteries are designed to go down to 5%. I wouldn't take them that low though.

Pylontech cellen zijn te krijgen bij

Akakale.com

Deze site heeft de cellen los te koop.

 

Pylontech cellen zijn te krijgen bij

Atakale.com

Deze site heeft de cellen los te koop.

 

Hi,

I have 8 batteries US2000C and in this period I notice a very different level of SOC:

Battery 1 and 8 are new and have firmware v3.0:

and battery 7 and others have firmware v2.5:

The cells voltage are the same but the SOC and Coulomb are different.

Since the voltage level of the batteries and cells is the same I'm not worried but I would like to be sure

Someone can tell me if this difference is a big problem and if the 12% of SOC can danger the battery?

Thank you

Edited December 10, 2025Dec 10 by Adrian Keller