MG5 LFP SOH Drama (88%) vs. Real Physics: Why the Display Lies (Experience Report + SIPS Updates)

[Jyrgo]

Hi everyone,

I’m sharing a deep dive into the SOH of my MG5 Standard Range (LFP, 50.3 kWh ,2022 facelift). As an electrical technician, I trust metered data over software estimates. My case is a perfect example of why you shouldn't panic over a dropping SOH display.

The Data:

• Vehicle: MG5 SR, ~70,000 km.
• SOH Display (BMS): 88.18% (via Car Scanner).
• Cell Health: Delta at 17% SOC was only 6 mV; at 85% SOC, it was a staggering 1 mV. Chemically, this pack is in "like-new" condition.

The Metered Proof:I performed a calibration charge from 8% to 100% SOC. The charging station meter showed exactly 47.74 kWh delivered.

The Math:

1. Charging 92% of the battery (8 to 100) means a full 0–100% charge would pull 51.89 kWh from the grid.
2. Even with a realistic 13% charging loss (AC/DC conversion, 12V overhead, cooling), that means approx. 45.1 kWh was actually stored in the battery.
3. A factory-new MG5 has a usable capacity of ~46 kWh.
4. This puts my real-world capacity at roughly 98%, completely contradicting the BMS claim of 88.18% (which would mathematically only be ~40.5 kWh).

Software & Range:I have updated the BMS along with several other key modules to the latest 2026 software baselines. I am still observing whether the range calculation has become more accurate as a result. Currently, at 85% SOC, it shows 245 km of range (with an average consumption of 16.0 kWh/100km). The SOH display remains very sluggish and seems to take a long time to reflect the new data.

Am I wrong?