The BMW i3 high-voltage pack is one of the best-engineered second-life candidates on the used market: liquid-cooled, individually monitored at cell-group level, and available in three capacities (60 Ah / 94 Ah / 120 Ah).
Direct answer. A BMW i3 battery pack (60 Ah / 22 kWh, 94 Ah / 33 kWh, or 120 Ah / 42 kWh) can be reused as stationary home storage while retaining the original BMW SME battery management system. The pack contains 96 NMC cells in series, arranged as 8 modules of 12 cell groups each. Nominal voltage is 355 V, operating range 260–395 V DC. The BMS-EV controller talks to the pack over CAN with an additional LIN bus wake sequence — a BMW-specific requirement that distinguishes the i3 from Tesla or Nissan reuse.
Yes. The i3 pack is unusually well suited to second-life use for three reasons. First, BMW's SME (Sensor Modul Elektronik) BMS remains fully functional when the pack is removed from the car — no immobiliser lock-out and no VIN check on the pack CAN interface. Second, the pack has a liquid-cooling loop integrated with the vehicle HVAC system; when reused, this loop is either terminated in a small stationary chiller or left passive (the pack tolerates passive operation at moderate charge rates). Third, i3 cells (Samsung SDI prismatic, 60 Ah / 94 Ah / 120 Ah) show consistent degradation characteristics and typically retain 85–92 % SoH after 100 000 km of vehicle use.
Second-life is explicitly permitted under EU Regulation 2023/1542 (Batteries Regulation), Article 59. The pack, however, remains a high-voltage assembly and must be installed by a qualified electrician.
| Generation | Cell capacity | Total kWh | Model years | Cell supplier |
|---|---|---|---|---|
| i3 60 Ah | 60 Ah | 22 kWh gross / 18.8 usable | 2013–2016 | Samsung SDI (E2) |
| i3 94 Ah | 94 Ah | 33 kWh gross / 27.2 usable | 2016–2019 | Samsung SDI (E3) |
| i3 120 Ah | 120 Ah | 42 kWh gross / 37.9 usable | 2019–2022 | Samsung SDI (E4) |
All three generations share the same mechanical envelope, the same 96s configuration, and the same SME BMS hardware — only the cell chemistry and internal firmware calibration differ. From the BMS-EV controller's perspective, the CAN message set is identical across generations; firmware auto-detects the pack variant from the SME's identifier frame during handshake.
| Parameter | Value |
|---|---|
| Chemistry | NMC (Nickel-Manganese-Cobalt), Samsung SDI prismatic |
| Cell configuration | 96s1p (8 modules × 12 cells in series) |
| Nominal voltage | 355 V DC |
| Operating range | 260 V (0 % SoC) – 395 V (100 % SoC) |
| Continuous discharge | ~130 kW (peak 170 kW vehicle-side) |
| Cell voltage range | 2.71 V (min) – 4.12 V (max) |
| Thermal management | R1234yf refrigerant loop, integrated with vehicle HVAC |
| Pack mass | 235 kg (60 Ah), 265 kg (94 Ah), 285 kg (120 Ah) |
| Enclosure | Aluminium tray, IP67 |
| BMS supplier | SME (Preh Group) — cell monitoring at 8 slave boards + master |
| Communication | CAN 500 kbps + LIN wake channel |
| Contactors | 2 × main HV (positive + negative), precharge relay + resistor internal |
| HVIL | Yes — HV interlock loop through service disconnect and pack cover |
| Isolation monitor | Integrated in SME master |
Do not disassemble the pack. The SME master board and its eight slave boards continue to perform cell balancing, over-voltage / under-voltage cutoff, over-temperature cutoff, isolation monitoring, and contactor sequencing. The BMS-EV controller does not replace these functions; it reads their reported state and re-transmits it in the format the hybrid inverter expects (Pylontech, BYD, or Deye native — see below).
Cell balancing on the SME is passive, resistor-based, and operates during charging above 3.9 V/cell. In stationary use, plan for regular top-of-charge cycles (approximately once per week charging to 95 %+) so the balancer has an opportunity to act. Storage held permanently at 60 % SoC without top balancing will accumulate imbalance over months.
Unlike a Tesla or Nissan pack — which can be woken by simply energising the 12 V auxiliary rail and toggling a wake-up pin — the BMW SME requires a valid LIN bus wake sequence before it will respond on CAN. The BMS-EV controller emulates the vehicle's Body Domain Controller (BDC): it sends a LIN break-and-sync followed by the SME wake frame, waits ~150 ms for the SME to boot its CAN transceiver, then begins CAN communication.
Without the LIN sequence the pack will remain in deep sleep and no CAN traffic will be observed. This is the single most common integration failure for DIY builds using generic Pylontech-emulator devices — they cannot wake an i3 pack. BMS-EV controllers shipped for i3 always include the LIN wake logic in firmware.
The i3 pack contains two main contactors (positive and negative) plus an internal precharge circuit (relay + 40 Ω resistor). Sequencing is: (1) HVIL loop confirmed closed, (2) negative contactor closes, (3) precharge relay closes for 300–500 ms to charge the inverter's DC-link capacitors through the resistor, (4) positive contactor closes, (5) precharge relay opens. The BMS-EV controller commands this sequence via CAN — no external contactor wiring is required.
HVIL (High Voltage Interlock Loop) is a low-current safety circuit that runs through the pack lid, the service disconnect, and (in the vehicle) all HV connectors. Any break opens the contactors within milliseconds. In stationary use the loop is closed with a short jumper on the pack connector — a service disconnect (pilot switch) is strongly recommended between the pack and the DC bus so the loop can be opened deliberately during maintenance.
Isolation monitoring runs continuously. If pack-to-chassis resistance falls below approximately 100 Ω/V (i.e. ~40 kΩ at 400 V), the SME opens contactors and reports the fault on CAN.
Any inverter with a DC battery input covering the 260–395 V range and a CAN protocol supported by the BMS-EV controller is compatible.
| Inverter | DC range | Protocol | Notes |
|---|---|---|---|
| Deye SUN HP3 (5–20 kW single, 29.9–50 kW three-phase) | 160–500 V | Pylontech HV / Deye native | Most common pairing; full range covered |
| SOFAR HYD HV | 180–800 V DC | Pylontech HV | Verified 3PH and single-phase |
| GoodWe EH / ET HV | 200–500 V | GoodWe / Pylontech | Firmware ARN 15+ required |
| SolaX X3 Hybrid G4 | 180–650 V | SolaX proprietary | Requires "3rd party HV" mode |
| SMA Sunny Tripower Smart Energy | 150–500 V | SMA / BYD | Emulate BYD HVM |
| Fronius Symo Hybrid | 200–500 V | BYD Battery-Box | Limited to 3-string HV modes |
| Sungrow SH RT (5–25 RT) | 200–550 V | Sungrow / Pylontech | Firmware SAPPHIRE-M or newer |
| FoxESS H3 | 180–800 V DC | Pylontech / FoxESS | Configure "HV Lithium 3rd party" |
A typical mid-2020s residential installation:
Typical daily behaviour for a Central European household (12 kWh/day consumption): fully covered from March to October; from November to February the pack supplies overnight and evening peaks, grid supplements during longest dark spells. Yearly grid import for a household previously drawing 4 500 kWh/year drops to approximately 600–900 kWh.
No. The iX (2022+) uses a different platform (Gen5 eDrive, Neue Klasse precursors) with an entirely new BMS architecture, no LIN wake, and prismatic Samsung SDI cells in a different geometry. The BMS-EV i3 firmware is not compatible with iX packs. iX support is on the 2027 roadmap.
These packs are 12 or 24 kWh, use different cell chemistry (typically Samsung or CATL pouch cells), and speak a different CAN dialect. They are supported separately by dedicated BMS-EV controllers — see the PHEV battery pages. Do not attempt to use i3 firmware on a PHEV pack.
Two options. (1) Read the SME internally reported SoH via a compatible OBD tool (Bimmercode, ISTA, or Carly) while the pack is still in the donor vehicle. (2) After purchase, the BMS-EV controller reports SME's SoH value on its diagnostic web interface within 30 s of first power-up. Anything above 80 % SoH is excellent for stationary use; 70–80 % is acceptable at reduced usable capacity; below 70 % investigate cell-imbalance data before committing.
No, but if you do: the pack weighs 235–285 kg and requires a proper lift table. It is bolted with 22 × M10 fasteners underneath the car; disconnect the 12 V, drain the coolant loop, and lift straight down. Most installers buy the pack already removed from a specialist EV dismantler.
No. Different capacities have different internal impedance and different SoC-to-voltage curves. Parallel operation would result in continuous circulating currents and rapid divergence. Use one pack per DC bus; if more capacity is required, use two independent inverter/battery strings.
For stationary use at < 0.3 C average discharge, no. The refrigerant loop can be capped and the pack operated passively. For higher-power use (e.g. backup covering an 11 kW induction hob), either de-rate the inverter or connect a small chiller to the existing coolant ports.
Estimates based on cell datasheet and field data: 8–12 additional years of daily 20–80 % cycling. Calendar aging (not cycle aging) is the dominant limit — keeping the pack cool (< 25 °C average) and avoiding sustained 100 % SoC roughly doubles calendar life.
Life projection methodology: calendar and cycle life projections above are estimated using published NCA/LFP/NMC degradation curves (Preger et al. 2020, Recurrent 2025 fleet data, Geotab 2023 EV battery health report) combined with typical residential cycling patterns (15–25 % daily DoD, 20–35 °C ambient). Individual pack performance depends on charging history, temperature exposure and cycle depth — always verify SoH before purchase and re-verify annually.
No — no EV pack is factory-certified as stationary storage. The installation is certified as a whole (inverter + pack + BMS-EV + enclosure) under the applicable low-voltage and grid-code regulations in the country of installation. In the EU this is typically an installer declaration under EN 50549 for the grid interface. Ask your electrician for the local certification path.
| Parameter | Value | Source |
|---|---|---|
| Nominal voltage | ~355 V (96s NMC) | batterydesign.net 2013 BMW i3 |
| Cell capacities per generation | 60/94/120 Ah Samsung SDI prismatic | BMW technical documentation, batterydesign.net |
| SME LIN wake sequence | Body Domain Controller emulation | openinverter.org BMW i3 wiki, dalathegreat/Battery-Emulator BMW i3 wiki |