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 LIM is also available new from BMW spare parts suppliers for € 240. If you get it new it comes without firmware and it needs to be programmed first.

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 Connectors and Pin Numbering

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, and reference for 1B-16.
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), referenced to 1B-5.

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?)(1.42V for 0V HV, linear to 4.8V for 500V HV)
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)(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.

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 (or: 1.42V for 0V HV, linear to 4.8V for 500V HV) from the high voltage DC voltage.

A circuit of a voltage sense board is shared here and can be purchased here.

Isolated DC Voltage sense board by muehlpower

An alternative voltage sense board is available here.

BMW i3 LIM voltage sense board by EVcreate

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 EVcreate

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

SAE 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 resistance 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 convenient 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 cable lock uses these connector parts:

• Connector shell: BMW 12527549033 or Hirschmann 805122541
• Terminals: BMW 61131393724
• Terminal seals: BMW 61138366245

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

Wake/sleep

The LIM will wake up under any of these circumstances:

• When 12V is applied to the hardware wake up line (1B-8).
• On plug insertion.
• On opening of the charge port door.
• When the LIM sees CAN message 0x12F.

The hardware wake up line works in both directions. I.e., the LIM can be woken by 12V on the hardware wake up line, but, similarly, when the LIM wakes up it will put 12V on the wake up line itself. This can be used to do things like waking up an OBC on plug insertion.

Programming a new LIM

If you order a new LIM there is no configuration loaded but our hero Damien managed to program a brand new LIM with a i3 BDC (Body Domain Controller).

https://openinverter.org/forum/viewtopic.php?p=43848#p43848

He caught a CAN log of the programming session: https://github.com/damienmaguire/BMW-i3-CCS/tree/main/Programming/Logs

Hopefully we figure out how to do it with a few CAN messages. In the meantime, Damien is offering LIM programming as a service: https://www.evbmw.com/index.php/evbmw-webshop/evbmw-serv/limprg.

Basic shopping list if you want to program a LIM:

• Software:
  • Esys 3.36 from here: https://disk.yandex.ru/d/3XLfVVYHFq8qQw
  • pszdata lite from here: https://disk.yandex.ru/d/Y0w0r5T1ElMVdA
• Hardware:
  • BMW LIM (see "LIM hardware" section below), connectors and pins (see "Connectors and Pinouts" section above).
  • BMW i3 BDC (Body Domain Controller): basically the main ecu in the i3 that gates all the data around the car.
    • Damien sourced his from: https://www.evbreakers.com/ noting They even threw in the plugs and few cm of harness for free.
    • According to realoem.com, the first BDC (used in 2014) was p/n 61359354010
      • A fuller list of the various BDCs over the subsequent years can be found here here:https://www.realoem.com/bmw/enUS/partxref?q=61359354010. Thankfully, there is a very wide retro/cross-compatibility
      • Also found some part numbers in ebay listings not seen in the realoem list (maybe a North America vs EU thing?):
        • 61-35-8-715-974, 61-35-5-A40-2F9
  • Car key from the same car as the BDC. EDIT: this may not be necessary as the BDC can be put into "on" mode by running the full fault delete function using ISTA
    • Wondering if a non-matching used or new fob could be used/reprogrammed if the BDC donor's VIN was known?
  • BDC simulator: https://www.aliexpress.com/item/1005002317110375.html
  • Enet cable: https://bcables.com/
  • USB to Ethernet adapter if your PC / laptop does not have a spare Ethernet port.
  • Two extra pins for Conn8 on the BDC to bring out PT CAN.
• DC power supply or 12v battery.

Charge control

The EVSE (charging station) shares its charging capacity limits via PWM during IEC 61851/ J1772 AC charging, or via PLC during DIN 70121 or ISO 15118 CCS sessions, but often the car cannot 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)

However, this temperature measurement is also done on the charger side, on the CCS cable itself. Chargers will protect themselves from overheating the CCS pins.The absolute max pin temperature allowed can range from 70-90*C depending on quickcharger brand.

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. Any VIN, or none, can be used.

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

Physical dimensions

The main body is 170mm x 42mm x 104mm. There are 2 mounting brackets with 192mm hole spacing. Total width is 215mm. The connectors on the front have additional 16mm to the main body.

https://openinverter.org/forum/viewtopic.php?p=51061#p51061

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
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

standard IEC61851 / J1772 charging sequence.

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 Design Guide for Combined Charging Systems by CharIn describes the basics of CCS charging very well.

https://openinverter.org/forum/download/file.php?id=1712&sid=59cf27578e4021c1e6dc01c73f46d8ee

This document actually covers Fast and Smart Charging Solutions for Full Size Urban Heavy Duty Applications, but since 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