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Reusing a BMW i3 22/33/42 kWh HV battery pack with an SMA hybrid inverter from the Smart Energy series. SMA uses a proprietary BAT-CAN protocol; the BMS-EV controller emulates an SMA-authorised battery device.
Short answer. A BMW i3 HV pack operates at 260–395 V DC and fits inside the SMA Sunny Boy Smart Energy 3.6–6.0 single-phase input range of 100–500 V and the SMA Sunny Tripower Smart Energy three-phase input range of 150–500 V. SMA does not accept Pylontech, BYD or generic protocols on the battery port — it uses its own SMA BAT-CAN protocol. The BMS-EV firmware emulates a compatible SMA battery.
| Inverter | Battery DC range | Power | Phase | Notes |
|---|---|---|---|---|
| SMA Sunny Boy Smart Energy 3.6 | 100–500 V | 3.6 kW | Single-phase | i3 fits (260–395 V) |
| SMA Sunny Boy Smart Energy 4.0 | 100–500 V | 4.0 kW | Single-phase | i3 fits |
| SMA Sunny Boy Smart Energy 5.0 | 100–500 V | 5.0 kW | Single-phase | i3 fits |
| SMA Sunny Boy Smart Energy 6.0 | 100–500 V | 6.0 kW | Single-phase | i3 fits |
| SMA Sunny Tripower Smart Energy 5.0 | 150–500 V | 5.0 kW | Three-phase | i3 fits |
| SMA Sunny Tripower Smart Energy 8.0 | 150–500 V | 8.0 kW | Three-phase | i3 fits |
| SMA Sunny Tripower Smart Energy 10.0 | 150–500 V | 10.0 kW | Three-phase | i3 fits |
BMW i3 vs SMA windows:
| SoC | i3 voltage | SMA SB SE (100–500 V) | SMA STP SE (150–500 V) |
|---|---|---|---|
| 0% (cutoff) | ~260 V | OK, 160 V above minimum | OK, 110 V above minimum |
| 50% | ~355 V | Centre of window | Centre of window |
| 100% | ~395 V | OK, 105 V below ceiling | OK, 105 V below ceiling |
Full BMW i3 range fits both SMA windows with margin.
SMA Smart Energy hybrids use the proprietary SMA BAT-CAN protocol on the battery interface at 500 kbps. This is not compatible with Pylontech, BYD or standard hybrid protocols. The BMS-EV controller:
Engineering values below are examples. Final conductor cross-section and protective-device sizing must be calculated for the actual pack, maximum current, cable length, installation method, ambient temperature and applicable local standards (IEC 60364-7-712, VDE-AR-N 4105, NEC 690).
No. SMA Smart Energy uses the SMA BAT-CAN protocol. This is one of the defining differences vs SolaX, FoxESS, Solis and Deye — all of which do accept generic protocols.
Sunny Boy Smart Energy = single-phase, 3.6–6.0 kW. Sunny Tripower Smart Energy = three-phase, 5–10 kW. Choose based on your grid connection.
3.10.xx or later. Older Smart Energy firmware may not include the battery protocol version the BMS-EV controller supports.
SMA Smart Energy inverters include integrated backup with an Automatic Transfer Switch (or Sunny Backup box). The BMW i3 pack provides discharge power up to the limit BMW BMS reports.
Yes for SoC and instantaneous power. Per-cell diagnostics require the BMS-EV local web UI.
Typical SMA Sunny Boy Smart Energy round-trip DC-to-AC-to-DC efficiency with an EV pack is 88–92%. Losses come mainly from the DC/DC and DC/AC conversions inside the inverter — the pack itself contributes ~1–2% resistive losses at typical loads.
No, not for operation. Only recommended once, before purchase, to read pack SoH.