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Other Resources:
FWXIV BMS Carrier notes
Components
Current Sense - connected via I2C, and provides current readings and cell temperature,
AFEs - 3 AFE boards, daisy-chained over iso-spi. These provide per-cell-unit voltage readings and Ambient temperature readings, as well as performing load balancing
Relays + killswitch monitoring - Positive and negative relays must both be closed for the battery to be connected to the rest of the car. Killswitch monitor reads state of manual killswitch to batteries
HV Neg relay
HV Pos Relay
HV Solar Relay
Fans - Used to provide cooling to batteries. Controlled via PWM and monitored for fault
Fault Conditions
These are all fault conditions which will trigger a BPS fault. They are split into Minor, in which the issue is likely to not be dangerous and the driver can take time coming to a stop, and Major in which the driver should exit the car as quickly as possible due to dangerous conditions or the potential for thermal runaway.
Note: Cell refers to individual input AFE measurements, which in reality is several physical cells. Cell group refers to an area managed by a single AFE.
AFE:
Undervoltage - One Cell Falls < 2.5V (minor)
Overvoltage - One cell > 4.5V (Major)
Balance - Across entire pack, if difference between max and min cells is > 0.05V (Major)
Temperature - if any thermistor reads > 60deg (Major)
Note: If thermistors read > 45deg, open solar relay to disable charging, but this is not a fault
Current Sense
Overcurrent - reading > 58.2A (Minor)
Temp > 60Deg (major)
KillSwitch
Will shutoff batteries by itself, but we will treat it as a BPS fault (minor)
Operation
BMS carrier sends/receives messages, which help it start up and operate properly.
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