BMW I3 Fast Charging LIM Module
The BMW LIM module is a CCS, CHAdeMO and AC charging controller. It is used to communicate between the vehicle and the public charging infrastructure, to allow fast charging to occur.
As these can be found affordably on eBay and from auto wreckers, they have been pursued as an open-source charger-interface project.
The LIMs are available new from BMW spare parts suppliers for € 240, but it is not confirmed if they come with firmware loaded, or if they need to be programmed at the dealer.
External links
github.com/damienmaguire/BMW-i3-CCS
> CAN logs
> STM32 ZombieVerter VCU software
Design Guide for Combined Charging System (2015)
EV Charging Definitions, Modes, Levels, Communication Protocols and Applied Standards
Connectors and Pinouts
All connectors are available at https://www.auto-click.co.uk/ worldwide.
| Label | Description | Compatible Plugs |
|---|---|---|
| 4B | 12 Pin Connector | BMW 61138373632
Audi 4E0 972 713 TE 1534152-1 / 1534151-1 |
| 3B | 8 Pin Connector (CHAdeMO models only) | BMW 61138364624
Audi 4F0 972 708 TE 1-1534229-1 |
| 1B | 16 Pin Connector | Hirschmann 805-587-545 |
| 2B | 6 Pin Connector | BMW 61138383300
Audi 7M0 973 119 TE 1-967616-1 |
| X | Replacement Pins | 5-962885-1 |
| X | Rubber Seal | 1-967067-1 |
| Pin # | Function | Description |
|---|---|---|
| 1B-1 | - | |
| 1B-2 | - | |
| 1B-3 | LED_M | Lighting Charge Socket? (Not necessary) |
| 1B-4 | LOCK_MOT+ | Charge Port Lock Motor |
| 1B-5 | LOCK_MOT- | Charge Port Lock Motor |
| 1B-6 | CAN_H | Powertrain CAN |
| 1B-7 | CAN_L | Powertrain CAN |
| 1B-8 | IGN | Wake up signal +12V (ignition, contact 15) |
| 1B-9 | VCC | Constant Power +12V |
| 1B-10 | GND | Ground |
| 1B-11 | - | |
| 1B-12 | - | |
| 1B-13 | - | |
| 1B-14 | - | Internally connected to GND |
| 1B-15 | CHARGE_E | Goes to KLE. Guessing this is charge enable or drive interlock signal? |
| 1B-16 | LOCK_FB | Charge Inlet Lock Feedback (1k unlocked, 11k locked) |
| Pin # | Function | Description |
|---|---|---|
| 2B-1 | CP | Pilot (charge port) ~620 ohms to GND is needed if no original i3 charge port is used! |
| 2B-2 | PP | Proxy (charge port) |
| 2B-3 | Jumper | Connected to Pin 4 |
| 2B-4 | Jumper | Connected to Pin 3 |
| 2B-5 | GND | Ground (charge port) |
| 2B-6 | US CCS1 version connected to 2B-2 |
3B Pinout:
- N/A (for CHAdeMO only)
| Pin # | Function | Description |
|---|---|---|
| 4B-1 | POS_CONT+ | Positive HV Contactor Control (Contactor coil resistance needs to be ~15 ohms) |
| 4B-2 | NEG_CONT+ | Negative HV Contactor Control |
| 4B-3 | POS_CONT- | Positive HV Contactor Control |
| 4B-4 | NEG_CONT- | Negative HV Contactor Control |
| 4B-5 | U_HV_DC | Charge port DC Voltage (current input 3-20mA?) |
| 4B-6 | LED_RT | Red charge Status Light (12V RGB LED) |
| 4B-7 | LED_GN | Green charge Status Light (12V RGB LED) |
| 4B-8 | LED_BL | Blue charge Status Light (12V RGB LED) |
| 4B-9 | LED_GND | Charge Status Light Ground (common cathode of RGB LED) |
| 4B-10 | COV_MOT- | Charge Port Cover motor (Not necessary) |
| 4B-11 | COV_MOT+ | Charge Port Cover Motor (Not necessary) |
| 4B-12 | COV_FB | Charge Port Cover Feedback (connect to GND to simulate open cover) |
Connector for BMW i3 CCS plug locking actuator is BMW part number 12527549033. Pins and seals should be the same as used on the LIM module.
Wiring Diagram
Wiring notes
Make sure you mount the LIM as close to the charge socket as possible and keep the pilot wire separate from the high power wiring.
Bad pilot wiring can result in SLAC, PLC, or other communication problems.
Additional components for a LIM installation
Isolated DC charge inlet voltage sense board
The LIM gets the inlet DC voltage from a board in the KLE.
This board needs to produce an isolated 3-20mA current signal from the high voltage DC voltage.
The circuit of the voltage sense board is shared here https://openinverter.org/forum/viewtopic.php?p=28143#p28143
Fast charge contactor
The LIM produces a 12V, 50% PWM on the positive and negative fast charging contactor outputs and measures the current draw of the contactors.
The BMW OEM fast charge contactor relays, located in the KLE, are (2) TE EVC135 RELAY, SPST-NO, DM (# 2138011-1).
https://www.te.com/usa-en/product-2138011-1.html
Similar, though not exact, replacements are available from EV Create https://www.evcreate.nl/shop/charging/contactor-matching-lim-ccs-charging-module-from-bmw-i3/
Larger contactor control
If you want to use larger contactors with PWM economizer or dual coil, use small relays to drive them and place a 15 ohms resistor (with heat sink) in parallel with each to simulate the original contactor coil's impedance.
Each of the two 15 ohm resistors must dissipate ~6W @ 13.4V, 50% PWM.
Further investigation is needed to find out if the LIM also detects a contactor failure via the current draw.
Charge port
SEA J1772 (US) and IEC 61851 (international) cover the general physical, electrical, communication protocol, and performance requirements for the electric vehicle conductive charge system and coupler.
https://en.wikipedia.org/wiki/SAE_J1772#Signaling
The original BMW i3 Type 1 charge port has 2.7 kΩ between PP and PE and no connection between CP and PE, as J1772 describes.
The Type 2 charge port used in Europe probably has 4.7 kΩ between PP and PE. (from Phoenix datasheet. Not confirmed!)
Make sure to match these if you want to use a different charge port. Some brands use different resistor values.
The CP communication is similar for US Type 1 (1-phase) and EU Type 2 (3-phase) charge ports, but the PP circuit is different and the lock mechanism is motorised for Type 2 and manual for Type 1.
Charge port lock
Only important for Type 2 (3-phase) charge ports.
In the BMW i3 a quite expensive Phoenix CCS charge port is used and it would be nice to be able to use the cheaper Duosida CCS charge ports.
The charge port lock should work with the Duosida lock as well but the feedback (1k unlocked, 11k locked) is a bit different which requires some additional resistors.
If using an OEM BMW i3 CCS charge port, the Kuster lock uses connector BMW 12527549033, around USD$4.
RGB charge indication light
The RGB charge indicator LED should have a common cathode and series resistors for 12V DC.
Nice push buttons with an integrated RGB LED are available on Aliexpress for a few dollars.
The switch signal is useful to stop charging and has to be connected to the ECU. The ECU then terminates the charging process over the CAN bus.
Charge control
The EVSE (charging station) shares its limits with PWM during IEC 61851/ J1772 AC charging or PLC during DIN 70121 or ISO 15118 CCS sessions, but often the car can not handle the max available power of the charging station.
The actual battery voltage and battery current values are needed by the LIM to check the response of the charging station. In this setup, the battery voltage and current are measured by an Isabellenhütte IVT CAN bus sensor, but these values could also be measured and shared on the CAN bus by the BMS. (CAN message 0x112)
Battery-dependent charging current control
During (fast) charging a cell voltage and cell temperature dependent current limit is very important.
The BMS or VCU should limit this value according to the battery specifications and protect the cells from damage and ageing at all times.
(Not yet implemented to the STM32 / ZombieVerter VCU project)
CCS inlet temperature sensors
Many CCS charge ports have DC and AC contact temperature sensors to avoid overheating if the contact resistance is high for some reason. The BMW's LIM has no temperature sensor inputs, but the VCU/charge controller could be connected to these sensors (usually PT1000 or NTC) and charging current could be reduced if the inlet gets too hot.
(Not yet implemented to the STM32 / ZombieVerter VCU project)
AC charging (on board charger control)
The LIM also handles the (lower level J1772 / IEC61851) communication during AC charging and shares measured PP (charging cable) and CP (charging station) AC current limits in the CAN message 0x3B4 EVSE info.
It is not possible to have two car-side charge controllers connected to the pilot line simultaneously. It is recommended to control the charger by CAN bus. If your charger needs the pilot signal, you will have to emulate it or switch the pilot connection wiring over to the active charger during AC charging.
If the onboard charger accepts an AC current limit, this value can be directly used but some chargers can only be controlled with DC current commands.
Because we don't know the actual AC current, we can only estimate it with a fixed AC voltage and charger efficiency.
DC_current = fixed_AC_voltage * CP_PP_current_limit * phase_count * charger_efficiency / DC_voltage
CAN communication
A DBC CAN database file can be found here: I3 LIM CAN dbc1
This list has to be cleaned up once we know which messages are actually necessary for the LIM.
| ID | Function | sent by | interval | Notes |
|---|---|---|---|---|
| 0x112 | BMS msg. | VCU or BMS | 10ms | could also be sent by BMS |
| 0x12F | Wake up | VCU | 100ms | needed |
| 0x3E9 | Main LIM control | VCU | 200ms | needed |
| 0x2F1 | Lim DC charge command 2. | VCU | 100ms | needed |
| 0x2FA | Lim DC charge command 3. | VCU | 80ms...1s | needed (low interval during CCS start up) |
| 0x2FC | Charge flap control | VCU | 100ms | needed (constant values work) |
| 0x431 | Battery info | VCU | 200ms | needed but does not control anything |
| 0x432 | BMS SoC | VCU or BMS | 200ms | display SoC needed |
| 0x03C | Vehicle status | VCU | 200ms | (constant values) needed? |
| 0x1A1 | Vehicle speed | VCU | 20ms | (constant values) 10ms works needed? |
| 0x2A0 | Central locking | VCU | 200ms | (constant values) needed? |
| 0x397 | OBD | VCU | 200ms | (constant values) needed? |
| 0x3F9 | Engine info | VCU | 200ms | (constant values) needed? |
| 0x3A0 | Vehicle condition | VCU | 200ms | (constant values) needed? |
| 0x330 | Range info | VCU | 200ms | (constant values) needed? |
| 0x51A | Network management | VCU | 200ms | (constant values) needed? |
| 0x540 | Network management 2 | VCU | 200ms | (constant values) needed? |
| 0x512 | Network management edme | VCU | 200ms | (constant values) needed? |
| 0x560 | Network management kombi | VCU | 200ms | (constant values) needed? |
| 0x510 | Network management zgw | VCU | 200ms | (constant values) needed? |
| 0x328 | Counter | VCU | 1s | needed |
| 0x3E8 | OBD reset | VCU | 1s | (constant values) needed? |
| Messages sent by LIM | ||||
| 0x29E | CCS charger specs | LIM | ||
| 0x2EF | Min. available voltage from the CCS charger. | LIM | ||
| 0x2B2 | Current and Voltage as measured by the CCS charger | LIM | ||
| 0x3B4 | EVSE info: CP, PP & inlet voltage | LIM | ||
| 0x272 | CCS contactor state and charge flap open/close status. | LIM | ||
| 0x337 | Inlet lock status | LIM | ||
LIM logs
Here you can find some CAN logs of AC and DC charging sessions. https://github.com/damienmaguire/BMW-i3-CCS/tree/main/CAN_Logs
QCA7005 SPI captures on Damien's GitHub https://github.com/damienmaguire/BMW-i3-CCS/tree/main/SPI_Caps
Observations
A VIN string is not required for AC or DC fast charging to function.
Functional LIMs have come from vehicles where the Air Bags have deployed, indicating that the module still works after a "Safety" event has occurred.
LIM hardware
LIM versions
Only "AC_DCO" versions work for CCS. Look for both "AC_DCO" and a MAC address on the label! If no MAC, the LIM is either AC-only or AC + CHAdeMO, and not useful for CCS.
| SN | IEC 61851
J1772 (AC) |
DIN 70121 | ISO 15118 | ISO 15118-20 | Cars | Used until | Tested |
|---|---|---|---|---|---|---|---|
| 61 35 9 346 827 | x | x | BMW i3 | ||||
| 61 35 9 346 820 | x | x | BMW i3 | ||||
| 61 35 9 353 646 | x | x | BMW i3 | Jul 2014 | x | ||
| 61 35 9 380 352 | x | x | ? | BMW i3 | Nov 2015 | ||
| 61 35 6 805 847 | x | x | ? | BMW i3 | Jul 2016 | ||
| 61 35 9 494 498 | x | x | ? | BMW i3 | 2018? | x | |
| 61 35 9 470 199 | x | x | ? | BMW i3 | ? | ||
| 61 35 9 454 319 | x | x | x | ? | BMW i3
Mini cooper SE |
now |
Power Limits
The limits for pre-2017/26 (Week 26 of 2017) are 0V-500V 0A-250A, post 2017/27 (Week 27 of 2017) 0V-1000V -500A-+500A.
This probably indicates when they moved from DIN 70121 only to ISO 15118.
Chips on the LIM board
| Chip | Description | Function | Datasheet |
|---|---|---|---|
| Renesas V850E2/FG4 | 32-bit Single-Chip Microcontroller | main MCU | https://www.renesas.com/us/en/document/dst/data-sheet-v850e2fg4 |
| Qualcomm QCA7000 | HomePlug® Green PHY, single chip solution | PLC Green PHY | https://openinverter.org/forum/download/file.php?id=9611 |
| Infineon TLE 7263E | Integrated HS-CAN, LIN, LDO and HS Switch, System Basis Chip | CAN, 2xLDO, wake-up | https://docs.rs-online.com/db13/0900766b814d680b.pdf |
| TI SN74LVC2T45-Q1 | Dual-Bit Dual Supply Transceiver with Configurable Voltage Translation | https://www.ti.com/lit/gpn/sn74lvc2t45-q1 | |
| NXP 74LVC1T45 | Dual supply translating transceiver | https://datasheetspdf.com/pdf-file/648034/NXP/74LVC1T45/1 | |
| STM L9951XP | Actuator driver | inlet lock motor | https://www.st.com/resource/en/datasheet/l9951.pdf |
| STM TS321 | Low-Power Single Operational Amplifier | https://www.ti.com/lit/gpn/ts321 | |
| TI LM2902 | Quadruple general-purpose operational amplifier | https://www.ti.com/lit/gpn/lm2902 | |
| STM VNQ5E250AJ-E | Quad channel high-side driver with analog current sense | LEDs?, contactors? | https://www.st.com/resource/en/datasheet/vnq5e250aj-e.pdf |
Charging protocols
Signaling circuit
AC charging
Usually the J1772 (US) or IEC61851 (EU) protocol is used for AC charging.
Some new charging stations support AC charging with ISO 15118 high level protocol as well, but it is not confirmed which versions of the LIM support it.
By default, the the EVSE (charging station) outputs +12V on the CP pin, and when connected to an EV will be reduced to 9V because of a load resistor present in the Electric Vehicle; this signals the EVSE that the connector has been plugged into a EV. After this, the EVSE will send a 1khz +12V to ‐12V square wave (PWM signal) and the duty cycle value corresponding to the maximum current it could deliver. If the EV is okay with that value of current, then it performs a handshake by changing the load resistance and dropping the PWM voltage to 6V, after which the charging begins.
In IEC61851, where untethered charging stations are allowed, the PP pin is used to detect the maximum power rating of the cable.
In the US, with J1772, where charging stations need to be tethered, the PP pin is used to detect if the manual unlocking mechanism is pressed, to stop the current flow before the plug is removed.
More information: https://en.wikipedia.org/wiki/SAE_J1772
CCS DC charging
DIN 70121 and ISO 15118 are quite complex high level protocols transmitted over PLC (power line communication) on the CP pin.
This document actually covers Fast and Smart Charging Solutions for Full Size Urban Heavy Duty Applications, but since most of the protocols used are similar it has comparable sequence diagrams, with descriptions for normal start up, normal shutdown, DC supply-initiated emergency stop and EV-initiated emergency stop.
https://assured-project.eu/storage/files/assured-10-interoperability-reference.pdf