BMW I3 Fast Charging LIM Module

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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

Forum discussion

github.com/damienmaguire/BMW-i3-CCS

> CAN logs

> STM32 ZombieVerter VCU software

> I3 LIM CAN dbc1

BMW I3 HV components

LIM Connector Kit

LIM Compatible Contactors

Design Guide for Combined Charging System (2015)

EV Charging Definitions, Modes, Levels, Communication Protocols and Applied Standards

Connectors and Pinouts

BMW i3 LIM CCS Charging Module

All connectors are available at https://www.auto-click.co.uk/ worldwide.

Connector Key (left to right)
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
X (for the connector on the i3's Charge Port Cable Lock,

see the Charge Port Lock section)

LIM pinout
1B Pinout:
Pin # Function Description
1B-1 LED_S Charge Port Lighting (not necessary)
1B-2 -
1B-3 LED_M Charge Port Lighting (not necessary)
1B-4 LOCK_MOT+ Charge Port cable Lock Motor
1B-5 LOCK_MOT- Charge Port cable 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 -
1B-15 CHARGE_E Goes to KLE. Guessing this is charge enable or drive interlock signal?
1B-16 LOCK_FB Charge Port cable Lock Feedback (1k unlocked, 11k locked)
2B Pinout:
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 Proximity (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)

4B Pinout:
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[1])(To be left floating for contactors weld test)

Wiring Diagram

Wiring LIM electric vehicle charge controller

Note [18Jun2022 ALS]: In the above diagram, some details may be non-current, eg the Charge Port Cover sensor is not shown, but its line @ 4B-12 must be floating (signalling that the Charge Port Cover is closed (?)) in order for the LIM to proceed with its welded contact tests; 4B-12 is tied to Ground (?) to indicate that the cover is open[2].

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.

Isolated DC Voltage sense board by muehlpower

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 ohm 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.

Gigavac contactor driver circuit

Charge port

DUOSIDA / MIDA CCS(2) inlet
DUOSIDA / MIDA CCS(2) inlet

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.

Charge port lock

In the BMW i3 a quite expensive Phoenix/Delphi 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.

BMW i3 CCS inlet lock actuator
BMW i3 CCS inlet lock motor actuator wiring w/pinouts


If using an OEM BMW i3 CCS charge port, the Kuster cable lock uses these connector parts:

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.

RGB LED

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)

Contactor Test

This is required before the LIM will proceed past the Precharge state during ccs charging.

To get it to do a contactor test following procedure has been determined

For LIMs 61 35 6 828 052 and later (to be confirmed)

  1. HV battery voltage to be present at vehicle side of contactors
  2. Charge Port door state is closed, feedback in 0x272 byte 2
  3. Charge Port Voltage Sense feedback with contactors open needs to be above 60V
    1. Fault set in 0x272 byte 2
  4. Ignition in 0x12F byte 2 needs to toggle from to OFF 0x88 to ON 0x8a
  5. LIM will cycle contactors during weld test and clear fault in 0x272 byte 2


For LIMs before 61 35 6 828 052 (to be confirmed)

  1. HV battery voltage to be present at vehicle side of contactors
  2. Charge Port door state is closed, feedback in 0x272 byte 2
  3. 12V permanent to be connected to the LIM
  4. Ignition in 0x12F byte 2 needs be ON 0x8a
  5. LIM will cycle contactors during weld test and clear fault in 0x272 byte 2

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.

Power Train CAN messages [500kbps]
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 value 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 "LIM_AC_DCO" versions work for CCS. Look for both "LIM_AC_DCO" and a MAC address on the label! If no MAC, the LIM is either AC-only ("LIM_AC") or AC + CHAdeMO ("LIM_AC_DCC"), and not useful for CCS.

LIM versions
Part No. 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 6 828 052 BMW i3 Aug 2019[3]
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

components
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

CCS1 vs CCS2 combo 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.

CCS-Charging-sequence.jpg

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