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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 — has become one of the best-value hatchbacks in Europe. 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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