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MG 4 (MG5 EH32) Battery for Home Energy Storage

The MG 4 — sold in Europe as MG4, built on SAIC's MG5 EH32 platform — is positioned in the value segment of the European hatchback market. Its pack is now appearing on the used market in meaningful volumes.

Battery variants

Variant	Capacity	Chemistry	Cell supplier	Years	Cooling
MG 4 SR	51 kWh	NMC pouch	SAIC (in-house)	2022+	Liquid
MG 4 LR	64 kWh	NMC pouch	SAIC / CATL	2022+	Liquid
MG 4 Trophy XR	77 kWh	LFP prismatic	CATL	2023+	Liquid

Pack topology and cell configuration

• 51 kWh NMC: 104 cells in series (approximately 104s1p), nominal ~385 V. Uses SAIC's OneBox modular architecture — 8 modules of 13 cells each.
• 64 kWh NMC: same 104s topology, higher-capacity cell chemistry. Nominal ~385 V.
• 77 kWh LFP Trophy: 108s LFP prismatic configuration (CATL cells), nominal ~346 V. Operating range 260–400 V.
• Pack weight: 320 kg (51 kWh), 380 kg (64 kWh), 450 kg (77 kWh Trophy).

Original SAIC BMS

SAIC develops its own BMS in-house under the MG and Roewe brands. The master BMS unit reports SoC, SoH, cell voltages, temperatures and current on the vehicle HS-CAN bus. Cell balancing is passive, overvoltage and undertemperature cutoffs are enforced autonomously. Contactor sequencing is handled by the BMS — the BMS-EV controller only needs to keep the "ignition on" heartbeat active.

CAN protocol notes

• Vehicle CAN runs at 500 kbps. BMS messages are broadcast on IDs in the 0x140–0x2A0 range depending on model year and pack variant.
• NMC vs LFP CAN differences: the 77 kWh Trophy LFP variant uses a distinct SoC estimation algorithm and reports cell voltages at a different scaling. Firmware must match the variant.
• Wake-up sequence: the SAIC BMS expects a wake frame from the vehicle gateway. The BMS-EV controller emits this frame at 100 ms cadence.
• Diagnostic UDS on the same bus — the controller ignores UDS traffic and forwards only the periodic broadcast frames.
• Trophy 77 LFP requires updated firmware: early BMS-EV releases (pre 2025-Q1) do not support the LFP variant. Verify firmware date at ordering.

Cooling

All three MG 4 pack variants are liquid-cooled through a serpentine cold plate under the modules. For residential reuse below 0.3 C, passive coolant fill is acceptable; sustained operation above 5 kW discharge benefits from a small 12 V pump keeping coolant circulating.

Compatible hybrid inverters

Inverter	DC input range	Compatible with	Notes
Deye SUN HP3	160–800 V	All MG 4 variants	BYD-Box or Pylontech-HV emulation
SOFAR HYD KTL-3PH	180–750 V	All MG 4 variants	SOFAR-HV protocol
GoodWe ET / EH	200–650 V	All MG 4 variants	GoodWe-native HV
SolaX X3 Hybrid G4 HV	180–650 V	All MG 4 variants	Triple MPPT
Sungrow SH-RT	200–800 V	All MG 4 variants	Sungrow HV protocol
Growatt WIT	150–800 V	All MG 4 variants	3-phase hybrid

Known limitations

• LFP 77 kWh Trophy requires firmware from 2025-Q1 or later — earlier controller batches only support NMC variants.
• NMC 51/64 packs age differently. The 51 kWh (higher C-rate per kWh) shows slightly worse SoH after 3 years of automotive use than the 64 kWh.
• SAIC diagnostic tooling is not widely available outside China — cell-level diagnostics can only be read via CAN broadcast, not UDS deep-dive.
• Chinese-market MG variants (MG5 sedan, MG Mulan) use the same pack but with region-locked VIN — flag at ordering.
• Cell voltage min/max broadcast interval is ~2 s — do not use for fast fault detection, rely on the BMS's own protective cutoffs.

Installation examples

• MG 4 64 kWh + SOFAR HYD 10KTL-3PH — 10 kWp PV, family home backup, €3 800 total.
• MG 4 Trophy 77 kWh LFP + Deye SUN 12K-SG04LP3-EU HV — 12 kWp PV with EV charging, €4 400 total.
• MG 4 51 kWh + GoodWe ET-15 — smaller home, 6 kWp PV, €3 200 total.

Order an MG 4 controller

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