# Bmw i3 bms



## Steel (Feb 12, 2018)

Hello, Tomdb !
Nice hearing about some progress I have a I3 batterypack and I'm very happy about this !!

BR Pär


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## thomas11 (Jun 30, 2019)

Jumping in on this topic:

I m planning on buying a BMW i3 120Ah 45V battery for my electric motor for my dinghy. 

Am I correct that it is not possible to get balancing/temp BMS for this battery without completely altering the battery? There is a nice cable that goes to all the cells but if there is no BMS that you can connect to this it will be not safe especially on the water if something goes wrong.


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## kennybobby (Aug 10, 2012)

*Re: Bmw i3 module and cell monitoring board*

Paul bought a module and brought it by so i could take a look. Sorry for the poor images, it was quite warm out and spur of the moment to grab a quick picture of the board. 

The module is quite heavy with 12s cells which seem to be Samsung cells (made in Korea) of about 50-55 Ahr. Cell dimensions about 7" x 2" x 5.5". Wrapped in a housing made of 6016-T4 aluminum. All welded terminals and measuring taps, so it won't be easy to reconfigure; but it's package so compact and well that it would be easier to just use as is.










The cell monitoring board uses a pair of LTC chips, one does the management, the other just provides a safety monitor according to the datasheets. This provides a bit of redundancy such as found on the tesla 3 and reported by Jack on evtv.










The balancing must be about 75mA with these 56R large-sized resistors in the world of surface mount. ~0.32 Watt










We could probably get better photos and more schematic details if needed.


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## pdove (Jan 9, 2012)

The Processor on the board is MC9S12P 64-pin package from Freescale Semiconductor used to be NXP. It also uses Si 8422AD isolator chips to talk between modules.

You can see on the lower board that pins 59 and 60 of the MC9S12P run across the board through a via to the other side and go to the Si 8422AD chip to the isolated part of the board and then run to the smaller connector the 12 pin one. They go to Pins 4 and 10 (CanL) and pins 5 and 11 (CanH) this connector goes daisy chain between the modules.


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## pdove (Jan 9, 2012)

The bigger connector goes to the cells and to an LTC6801 and LTC6802 to monitor the voltage and the temperature of the cells. Looks like there is a diode between each cell most positive --|>|-- to negative across cell. Looks like the 6801 is used for discharge and 6802 is used charge and balancing the diodes go the --|<|-- on the 6802The bigger connector goes to the cells and to an LTC6801 and LTC6802 to monitor the voltage and the temperature of the cells. Looks like there is a diode between each cell most positive --|>|-- to negative across cell. Looks like the 6801 is used for discharge and 6802 is used charge and balancing the diodes go the --|<|-- on the 6802


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## colourmecarbon (Oct 9, 2017)

very interested in this thread, I’m hoping to convert my Type2-only i3 charging port to a CCS with fast-DC version.
I can’t find detailed part number info for the BEV models that have the ccs-dc, so I don’t know if the KLE EMS are bypassed and the HV cabling goes directly to the battery.
From what you’ve found in the BMS, do you think it would be possible to directly connect the DC pins to charge the battery and let the BMS control the input without major work to the onboard charging components?


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## kennybobby (Aug 10, 2012)

These are just the CMU board found on each module--Cell Monitoring Units that can only report back thru the CAN buss to some higher-level controller such as a Battery Management System or BMS unit.

i haven't studied up on the i3 system so this is just based upon my experience with other OEMs: The BMS likely talks to an even higher level Electric Vehicle Control Unit, which handles the communication between the car and the Chademo or CCS DC station, aka EVSE Level 3. Due to safety concerns with HV i'm sure that chargging is controlled at a much higher level than these CMU boards.

You may be able to use Tom's board to integrate some sort of diy controller for the cell voltages, but i'm not sure that anyone has reverse engineering the level 3 protocol. Anyone know if it has?


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## pki (Dec 20, 2019)

Hi.

I have installed the i3 battery pack into our EV. I have a few basic questions.
- Does the BMS modules on each battery pack will work stand alone, or do they need more?
- I also have the SME BEV13 D1 module, i think the BMS management?'
- I also have the onboard charger box.

I would like to get the AC charging to work. Do I need more from BMW, or should this parts be sufficent and can work without the other electronic from BMW?


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## colourmecarbon (Oct 9, 2017)

is the car you’re building an i3 or a custom diy conversion?


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## pki (Dec 20, 2019)

Its a converted berlingo with MED-DEA/Venturi drive, the drive is working, i am working on a way to charge it.


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## Ruwanga (Dec 18, 2019)

Hi everyone! 
Could anyone of you share the specifications /value of NTC thermistor used as Temp sensors in the module? (*Resistance Kohm and B value?*) It seems each LTC connects to two thermistors and i cannot figure out whether all 4 thermistors are the same or even different, and what are the values. 
Any feedback in this regard is much appreciated!


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## pdove (Jan 9, 2012)

Ruwanga said:


> Hi everyone!
> Could anyone of you share the specifications /value of NTC thermistor used as Temp sensors in the module? (*Resistance Kohm and B value?*) It seems each LTC connects to two thermistors and i cannot figure out whether all 4 thermistors are the same or even different, and what are the values.
> Any feedback in this regard is much appreciated!


Can't see them. The are encapsulated with black goo and underneath metal tabs on the battery. Scroll up to the battery picture and look at the yellow wires that go to the cell next to the most positive cell. They are glued down under those tabs. However looking at the board it looks like pins 2, 3, 15 and 16 go to ground and pins 1, 4, 14, and 17 go to a circuit. All of these pins go to the thermistors. You can follow the yellow wires.


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## Robocop (Feb 26, 2021)

Tomdb said:


> I have been able to decode some of the I3 battery Can bus.
> 
> Currently I have working:
> -Cell Voltages
> ...



Thanks for the answer, I tried to figure it out before ...I decided to contact the developer directly
Sorry, I don't understand your program. Please help with an example of a single post ID. 
For example (which I have already figured out) to the request ID0A0 37 01 00 00 00 00 FF FF we will receive a response from block 2 ID1A1 with its parts number. I don't understand the id request and the answers for cell voltages,temperatures in separate cells in the block and the most important error messages in it ...I can not find how the block gives an error and blocks the battery
BMW i3 Slave Connector pin 3,9 (blue)Did you manage to figure out the purpose and exchange of this bus?


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## Aadithya2410 (Feb 27, 2021)

Hi. I have a doubt regarding a part in the SIMP BMS code. I am not sure if this is the right place to ask but could someone please explain why there are only 5 Module ID requests when there are in total if I am not wrong, 8 Modules??


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## scottherrington (Jul 3, 2020)

There are definitely 8 battery modules however each module has it's own BMS with 4 temperature sensors in each module. Still not sure how that adds up to 5 though. Would there be temperature sensors as part of the battery heating/cooling system?

Sent from my moto g(8) power lite using Tapatalk


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## Aadithya2410 (Feb 27, 2021)

scottherrington said:


> There are definitely 8 battery modules however each module has it's own BMS with 4 temperature sensors in each module. Still not sure how that adds up to 5 though. Would there be temperature sensors as part of the battery heating/cooling system?
> 
> Sent from my moto g(8) power lite using Tapatalk


Thank you for the answer. But I was assuming this part of the code is to detect the module, as in which module is sending the data and not the temperature data within the module. If that is not the case, did anyone find out which part of the SIMPBMS code sends request for Module ID to read data from specific Module. Because it is designed to connect to 8 separate modules right??. Can you help me out here?? thanks


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## scottherrington (Jul 3, 2020)

Could it be messages from other components that the BMS relies on? Like the charge port door etc?

Sorry if I'm suggesting stupid things.

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## scottherrington (Jul 3, 2020)

Aadithya2410 said:


> Hi. I have a doubt regarding a part in the SIMP BMS code. I am not sure if this is the right place to ask but could someone please explain why there are only 5 Module ID requests when there are in total if I am not wrong, 8 Modules??
> 
> View attachment 122108


As it returns a 'break' does this mean it is either on or off? If so could be charging interlocks, is the cable attached? Door open etc

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## Aadithya2410 (Feb 27, 2021)

scottherrington said:


> As it returns a 'break' does this mean it is either on or off? If so could be charging interlocks, is the cable attached? Door open etc
> 
> Sent from my moto g(8) power lite using Tapatalk


Yeah that is true. It is definitely something else and I guess only by testing we can figure what it actually is for. But I have still not found the IDs for the modules in the code. Maybe I need to look better but I dont see the 8 IDS of modules, where it is being detected. Needed help in which part of code reads the Module ID and what are the Hex values of them.


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## scottherrington (Jul 3, 2020)

The Lim has inputs from central locking etc, these are identified as modules in the pic.









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## amsmntparks (Jan 4, 2018)

I'm looking to buy a pack from a salvage yard, but want to check if it's any good. Does anyone have the pinout for the battery pack main connector? Will I be able to pull the individual cell/module statuses with the simp connected to the CAN bus of the entire pack? Thanks!


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## Roadstercycle (Jun 26, 2019)

amsmntparks said:


> I'm looking to buy a pack from a salvage yard, but want to check if it's any good. Does anyone have the pinout for the battery pack main connector? Will I be able to pull the individual cell/module statuses with the simp connected to the CAN bus of the entire pack? Thanks!


Just pull the top and do individual checking. That's what I did. A lot of screws but it's pretty simple to do. Electric screw gun and a 10 mm socket. And of course a multi-meter.


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## Martii (Jan 17, 2018)

Tom did you ever try to run master BMS without a car? Would be nice to use current sensor integrated in there.



Tomdb said:


> I have been able to decode some of the I3 battery Can bus.
> 
> Currently I have working:
> -Cell Voltages
> ...


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