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The inverter shows one SOC, the battery shows another — or the figure is frozen solid. Before you reach for a settings menu, check whether you have a communication problem or a genuine calibration problem. They look the same and they fix completely differently.

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Check first

Work through these before doing anything else:
1

Confirm the link is closed-loop right now

The SOC on the inverter display must be updating. A frozen or missing SOC is a comm problem, not a calibration problem. Go to Cable Checks and resolve the cable before continuing.
2

Check for recent events

A comm repair, a firmware event, or a long spell at low power are the three classic triggers for SOC drift. Note which applies before you proceed.
3

Record the readings and the time

Note both the inverter SOC and the battery’s own SOC indication right now. Kent service will ask for these.

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Why SOC drifts

The comm link fell back to voltage estimation. When the BMS link is down, the inverter estimates SOC from DC voltage. On lithium chemistry, that estimate wanders badly through the flat middle of the charge curve. The fix is to restore the comm link first — the mismatch itself is then just history. A long spell at low power. The Kent G3 source manual states this directly: when a lithium battery stays at low power for an extended period, the SOC measurement loses accuracy and the pack needs a full charge to 100 % to restore it. Sites with minimal load overnight are particularly prone to this.

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Recalibrating on the Kent G3

The Kent G3 has an official tool for SOC recalibration: the Battery Healing switch, found in the professional Function Settings menu. With Battery Healing switched ON, the system charges the pack from low SOC — grid assists from the Force-charge SOC setpoint up to the Overdischarge SOC, then PV takes priority up to the Battery Healing SOC target. The battery does not discharge until that target is reached, which re-anchors the SOC measurement.
Professional-menu access is partner-gated. See Authorized-Only Actions before using this function on a customer site.

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Recalibrating on the Kent M1

Pending Kent validation. [KNB-VAL-22] The Kent M1 SOC recalibration procedure is under confirmation with the Kent battery team. Until published here: after restoring comms, bring the bank to 100 % through normal operation — a planned charge window or a high-PV day. Verify that the inverter SOC then tracks the battery’s own indication, and record both readings. Do not force-cycle the bank to empty as a “calibration” step. A mismatch that survives a verified full charge is an escalation — not a settings problem.

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After any BMS comm repair

Whatever the platform: once the link is confirmed live, run the bank through a full charge and verify both SOC readings agree before closing the job. Drift accumulated during a comm outage does not clear itself — the full charge is the reset. Record the post-repair readings on the service sheet.

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Common mistakes

A frozen SOC is a comm fault until proven otherwise. Go to Cable Checks first — never open a settings menu for a frozen reading.
Lithium chemistry has a very flat mid-curve. A voltage that looks normal proves almost nothing about SOC accuracy.
The charge cycle is what resets accumulated drift. A comm repair is not complete until both SOC readings agree after a full charge.
Sites that sit at low SOC for long periods develop chronic SOC drift. See Not Charging / Not Discharging for the settings that prevent it.