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1kWh Li-Ion Geek communication question

Discussion in 'Gen 4 Prius Technical Discussion' started by Leckan, Dec 27, 2020.

  1. Leckan

    Leckan New Member

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    Hi

    So I purchased a 2018 Prius Plus 1kWh Li-Ion battery (G9280-47180) the other week. This should be used as a powerpack for another project, but I bumped into a “small” problem… I have experience in CAN communication and I was hoping to reuse the Battery Voltage Sensor for reading out cell voltages, SOC, temps, currents etc. (as in Gen2) but found out that this battery ECU might not use CAN but some other differential communication standard. I only get Error frames when hooking it up with a CAN dongle and when looking at the signals in a scope it do not look CAN-isch and the bitrate seems to be at 10kbps only.

    Anyone in this forum knows what communication type this battery uses and if this could be decoded?

    If not, does someone know which ECU the Battery Voltage Sensor communicate with and if this ECU might have a CAN interface?

    IMG_20201222_100901.jpg

    All help needed Cheers!
     
    #1 Leckan, Dec 27, 2020
    Mambo Dave likes this.
  2. ChapmanF

    ChapmanF Senior Member

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    I don't have the answer but I know where you'll probably find it: in the "Multiplex Communication" section of the New Car Features manual for that year and model, or if not there, in that section of the same manual for the first model year of that generation. Information on access to the manuals can be found here.
     
    #2 ChapmanF, Dec 27, 2020
    alanclarkeau likes this.
  3. Leckan

    Leckan New Member

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    Thanks!
    Found a lot of interesting information, among that the Battery Voltage Sensor is not CAN, LIN or AVC-LAN (Audio Visual Communication-Local Area Network) based. The Sensor was not explained in the Multiplex Communication section (for whatever reason..?) or in any System diagrams. One picture states “Serial Communication” for this sensor and in the wiring schematic one finds that it uses 2 wire shielded communication between the sensor and the Hybrid Vehicle Contro ECU, named BTH+ & BTH-. So, I guess all this info says that it’s not possible to tap into the Battery Voltage Sensor directly.

    Not sure if it’s worth buying a matching Hybrid Vehicle Control ECU and try to hook them up (a lot of pins on the HVC and I still do not have the CAN .dbc for this unit either) or if it’s better to buy a universal 56S BMS and start from scratch. Someone here might already have done that?
     
    #3 Leckan, Dec 28, 2020
  4. Eric Nelson

    Eric Nelson New Member

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    On my Gen2 pack the BTH+ / BTH- are LIN but transmitted differentially. I was able to use a NJM2903D comparator to convert back to single ended LIN, but I have no tools to decode it. I also have a Gen4 Li-ion pack which has 2 CAN ports. I've looked at CAN1 on my scope and the signal is either 100kbps or 125kbps transmission. The scope's CAN decoder looks happy; decoding CAN IDs, data, and the checksum. I'll use a protocol analyzer instead and try to decode. I need the cell voltages.
     
    #4 Eric Nelson, Oct 6, 2022
  5. Eric Nelson

    Eric Nelson New Member

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    The CAN signal can be decoded at 250kbps and 500kbps on my scope. I'm not sure which baud rate is correct based on the hex I'm getting out. I need to figure out how to trigger on a specific ID.
     
    #5 Eric Nelson, Oct 6, 2022
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