This is a voltage curve of a new CATL LFP. I didnt use any time to try match the CATL LFP cell Tesla use. Its about the right size, and a recent model.The link of the graph in my previous post is of LFP. It shows 3.2V at 20% SOC.
Take note that this is a 0.5C discharge curve ( like driving so fast that it goes from 100 to 0% in two hours).
The open circuit voltage will be higher, and the voltage with the car parked and looking at SMT will also be higher.
The X-axis shows Amphs. We have 8 fields (0-20, 20-40 etc.)
SOC-wise, the first 0-20Ah will contain more energy then the other and much more then the 160-180Ah field.
The first field will contain more than 1/8 of the SOC and the last will contain much less than that, maybe 1/10 or 10% or slightly less.
You probably have the 8.8% mark at about the 140Ah or precisely right of. So, that looks like 3.17 V or so. If the battery is unloaded from that 0.5C load, the voltage increases. Most probably up to the 3.20V line or so.
CATL 161Ah LiFePO4 Battery