hitl_tester.test_cases.bms.test_q_max

  1"""
  2See: https://github.com/turnaroundfactor/battery-benchtop-rev1/issues/244
  3
  4Fix issues with q_max accuracy being off.
  5
  6The full test plan is below.
  7
  81. Charge the pack completely, let it rest overnight.
  92. Discharge it and pause at all OCV intervals (95, 90, 80, 70...)
 103. During the pause set discharge current to 0 for 5-10 seconds
 114. Measure the voltage during this time
 125. Take notice of the voltage difference between when its charged and discharged
 13"""
 14
 15import pytest
 16
 17from hitl_tester.modules.bms.bms_hw import BMSHardware, UserInterrupt
 18from hitl_tester.modules.bms.plateset import Plateset
 19from hitl_tester.modules.bms_types import DischargeType
 20
 21# Global Variables that can be shared between tests
 22MINUTE = 60
 23HOUR = 60 * MINUTE
 24
 25MAX_CHARGE_TIME = 12 * HOUR
 26CHARGE_VOLTAGE = 16.8
 27CHARGE_OV_PROTECTION = 16.85
 28CHARGE_CURRENT_A = 3
 29CHARGE_TERMINATION_CURRENT = 0.1
 30CHARGE_SAMPLE_INTERVAL = 1
 31MIN_READINGS = 3  # How many readings to take before passing (for erroneous readings).
 32
 33MAX_DISCHARGE_TIME = 12 * HOUR
 34MAX_DISCHARGE_STEP_TIME = HOUR
 35DISCHARGE_CURRENT_A = 2
 36DISCHARGE_VOLTAGE = 10
 37DISCHARGE_UV_PROTECTION = 9.95
 38DISCHARGE_SAMPLE_INTERVAL = 1
 39
 40RESTING_TIME = 30
 41RESTING_SAMPLE_INTERVAL = 1
 42
 43CAPACITY = 11.485347  # Set by the discharge cycle (value from last Q max test)
 44
 45bms_hardware = BMSHardware(pytest.flags)  # type: ignore[arg-type]
 46bms_hardware.init()
 47plateset = Plateset()
 48
 49bms_hardware.csv.cycle = bms_hardware.csv.cycle_smbus
 50bms_hardware.remaining_capacity_percentage = 100
 51
 52
 53def standard_step_discharge(
 54    percent_discharge: float,
 55    total_ah: float,
 56    max_time: float = MAX_DISCHARGE_STEP_TIME,
 57    discharge_i: float = DISCHARGE_CURRENT_A,
 58    discharge_sample_interval: float = DISCHARGE_SAMPLE_INTERVAL,
 59    uv_protection: float = DISCHARGE_UV_PROTECTION,
 60):
 61    """Run a step discharge cycle."""
 62    bms_hardware.max_time = max_time
 63    bms_hardware.current = discharge_i
 64    bms_hardware.sample_interval = discharge_sample_interval
 65    bms_hardware.uv_protection = uv_protection
 66    bms_hardware.percent_discharge = percent_discharge
 67    bms_hardware.total_ah = total_ah
 68
 69    bms_hardware.run_discharge_step_cycle()
 70
 71
 72def standard_rest(max_time: float = RESTING_TIME, sample_rate: float = RESTING_SAMPLE_INTERVAL):
 73    """Run a resting cycle."""
 74    bms_hardware.max_time = max_time
 75    bms_hardware.sample_interval = sample_rate
 76    bms_hardware.run_resting_cycle()
 77
 78
 79def test_full_charge_cycle_1():
 80    """Completely charge cells."""
 81    bms_hardware.voltage = CHARGE_VOLTAGE
 82    bms_hardware.ov_protection = CHARGE_OV_PROTECTION
 83    bms_hardware.current = CHARGE_CURRENT_A
 84    bms_hardware.termination_current = CHARGE_TERMINATION_CURRENT
 85    bms_hardware.max_time = MAX_CHARGE_TIME
 86    bms_hardware.sample_interval = CHARGE_SAMPLE_INTERVAL
 87    bms_hardware.minimum_readings = MIN_READINGS
 88
 89    plateset.ce_switch = True
 90    bms_hardware.run_li_charge_cycle()
 91    plateset.ce_switch = False
 92
 93
 94def test_full_discharge_cycle():
 95    """Completely discharge cells. Required to get capacity."""
 96    global CAPACITY
 97
 98    bms_hardware.max_time = MAX_DISCHARGE_TIME
 99    bms_hardware.sample_interval = DISCHARGE_SAMPLE_INTERVAL
100    bms_hardware.discharge_type = DischargeType.CONSTANT_CURRENT
101    bms_hardware.current = DISCHARGE_CURRENT_A
102    bms_hardware.uv_protection = DISCHARGE_UV_PROTECTION
103    bms_hardware.voltage = DISCHARGE_VOLTAGE
104
105    CAPACITY = bms_hardware.run_discharge_cycle()
106    print(f"Ah = {CAPACITY}")
107    assert CAPACITY != 0  # make sure we didn't get an error
108
109
110def test_full_charge_cycle_2():
111    """Completely charge cells."""
112    bms_hardware.voltage = CHARGE_VOLTAGE
113    bms_hardware.ov_protection = CHARGE_OV_PROTECTION
114    bms_hardware.current = CHARGE_CURRENT_A
115    bms_hardware.termination_current = CHARGE_TERMINATION_CURRENT
116    bms_hardware.max_time = MAX_CHARGE_TIME
117    bms_hardware.sample_interval = CHARGE_SAMPLE_INTERVAL
118    bms_hardware.minimum_readings = MIN_READINGS
119
120    plateset.ce_switch = True
121    bms_hardware.run_li_charge_cycle()
122    plateset.ce_switch = False
123    UserInterrupt.force_pause()  # Suspend the test
124
125
126def test_step_discharge():
127    """Record the voltage at each state of charge."""
128    soc = 100
129    ocv_steps = (100, 95, 90, 80, 70, 60, 50, 40, 30, 20, 10, 7.5, 5, 2.5, 0)
130    for new_soc in ocv_steps:
131        if new_soc != ocv_steps[0]:
132            if new_soc == ocv_steps[-1]:
133                bms_hardware.discharge_until_undervoltage = True
134            standard_step_discharge((soc - new_soc) / 100, CAPACITY)
135        standard_rest()
136        soc = new_soc