I have four lithium batteries connected in parallel, each with a capacity of 10 KW

The problem is that when the SOS percentage for all four batteries is 100%, the voltage of the four batteries is not equal.

Note that the BMS type is JBD

That is quite normal, the voltages of each battery will never be the same due to various factors (age, cell resistances, connections, cables etc etc).
However if there is a very big difference then interrogate the batteries more closely to ensure all the cells are in good health and that your balancing is working correctly.

30 minutes ago, WannabeSolarSparky said:

very big difference

How does one quantify a big difference? On my 2S5P arrangement for my 10 GEL batteries, when I check the battery balancer voltages, the difference is about 0.03V. That is the most I have seen. Last time I disconnected them to measure with a meter, they were all within 0.05V of each other. For lithium, when does one get worried? I am interested in knowing, as in the next 3 to 4 years, I would probably need to replace the batteries.

2 minutes ago, Denns said:

How does one quantify a big difference? On my 2S5P arrangement for my 10 GEL batteries, when I check the battery balancer voltages, the difference is about 0.03V. That is the most I have seen. Last time I disconnected them to measure with a meter, they were all within 0.05V of each other. For lithium, when does one get worried? I am interested in knowing, as in the next 3 to 4 years, I would probably need to replace the batteries.

Usually with lithium batteries you would check the individual cells voltages, you will quickly notice/see a cell or cells that have problems as the will usually be a few milli-volts away from the average.
Good healthy cells in a battery pack should never be more than 0.005 volts away from the average. if they are then it could indicate a bad cell or improperly balanced cell.

You say 3 - 4 years, by that time I think other chemistries may or may not be available that may work differently.

All batteries are of the same age, but there is a difference in electrical voltage between all the cells inside the battery.

Someone told me that all batteries need their cell readings adjusted using BBMS Tools software.

I will go to the battery website and attach a photo of the cell voltage reading.

18 minutes ago, ahmad almawal said:

Someone told me that all batteries need their cell readings adjusted using BBMS Tools software.

Provided they have a Pace BMS or PACE-type functionality inside.

By default, batteries are pre-set by factory for longevity, reliability etc.

One can however, change settings with correct knowledge to suit each different scenario. E.g. when temperature alarms should activate, is far to harsh, specially if one lives in a mild climate.