The battery pack is configured as 2S1P using Samsung INR18650-35E cells.
When discharging with a constant nominal current, the SOC drops sharply from 20% to 1-2%, then stays at 1% until the nVEmpty cell voltage (3.00V) is reached, then goes to 0%.

MAX17215
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The MAX1720x/MAX1721x are ultra-low power stand-alone fuel gauge ICs that implement the Maxim ModelGaugeâ„¢ m5 algorithm without requiring host interaction...
Datasheet
MAX17215 on Analog.com
The battery pack is configured as 2S1P using Samsung INR18650-35E cells.
When discharging with a constant nominal current, the SOC drops sharply from 20% to 1-2%, then stays at 1% until the nVEmpty cell voltage (3.00V) is reached, then goes to 0%.

Here is a log showing the behavior. There are 3 full charge/discharge cycles, followed by a charge to 26% SOC (starting 7/15/2025 14:03), then 5 minutes, then discharge. SOC goes from 26% immediately to 2.9%, then falls to 1% for remainder until reaches nVempty (3.00V), then goes to 0%.SOC Drop.zip
Included the config INI file in the zip as well.
Hi,
Did you get round this issue? I am trying to use INR21700 cells with Modelgauge m5 and I have various issues like jumping RepSoc or stuck RepSoc. I have tried the LCO and NCA models but it doesn't make much difference.
Thanks