Validation - BMS Carrier

Owned by Liam Hawkins
Last updated: Sept 07, 2020

Power Validation

  1. Check for continuity between GND, 3.3 V, 5 V, and 12 V. All of these should be isolated from each other.
  2. Supply 12 V between GND and 12 V. A current limit of 100 mA should be sufficient for most testing. Switching the relays and/or fans will require more current (up to 4 A). Measure the voltage between GND and 3.3 V, and GND and 12 V.
  3. Write 0x400920 to the MCP23008 to enable the 5 V converter. Measure the voltage between GND and 5 V.
  4. Turn off the power supply.

HSD Current Sense Output (TPS2H000-Q1)

  1. Short the kill switch connector (pins 1 and 3).
  2. Supply 12 V between GND and 12 V.
  3. Enable IN2 and DIAG_EN of the HSD using the IO expander.
  4. Measure the voltage of the HSD CS (PB1).
  5. Set the kill switch enable signal to high (PB9). The relay should close.
  6. Measure the voltage of the HSD CS (PB1).
  7. Compare the two measurements. The first should be about 0 V and the second should be about 1.2 V.
  8. Turn off the power supply.

isoSPI (LTC6820)

  1. Connect an isoSPI slave (current sense or AFE) to one of the isoSPI ports.
  2. Supply 12 V between GND and 12 V.
  3. Run a smoke test for the board that is connected (smoke_ads1259 for current sense, smoke_ltc6811 for AFE).
  4. Repeat for each SPI.
  5. Turn off the power supply.

The process above is the easiest way to check if the LTC6820s are working, but if other boards are not conveniently accessible, here is an alternative procedure:

  1. Connect an oscilloscope to the IP and IM signals. Set it to single trigger mode.
  2. Supply 12 V between GND and 12 V.
  3. Run a smoke test listed above.
  4. There should be a long -1 pulse followed by the data, which consists of short -1 and +1 pulses (see datasheet for a description of the types of pulses). There should be a +1 pulse at the end of the data, but the oscilloscope may not record the entire transmission.
  5. Turn off the power supply.

Capacitor Inrush Current

  1. Short the kill switch connector (pins 1 and 3).
  2. Connect a shunt resistor between the negative terminal of the power supply and the negative terminal of the BMS carrier board.
  3. Connect an oscilloscope probe across the shunt resistor, with the ground terminal of the probe connected to the negative terminal of the power supply. Set the oscilloscope to trigger a single time.
  4. Power the BMS carrier board with 12 V between 12 V and the negative terminal of the shunt resistor. Toggle the output of PB9 on and off. Turn off the power supply.
  5. Determine the peak voltage, and divide by the resistance of the shunt resistor. The peak current should be less than 1 A.

Enable Relays

  1. Close the kill switch or short the connector.
  2. Supply the board with 12 V between GND and 12 V.
  3. Set PB9 high to enable the HSD and activate the relay to power the main relay coils. There should be an audible click as the on-board relay closes.
  4. Set PB4 high to enable the low side switch of the HV GND relay coil. The LED for the HV GND relay should turn on.
  5. Set PB3 high to enable the low side switch of the HV PWR relay coil. The LED for the HV PWR relay should turn on.
  6. Turn off the power supply.

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