Architecture & Functional Components Flashcards
7 cards from real BMS practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Architecture & Functional Components flashcards as text
Which communication protocol is commonly used between a BMS master and the vehicle ECU in automotive applications?
Answer: CAN bus (Controller Area Network)
CAN bus is the dominant automotive communication standard, offering noise immunity, multi-master capability, and deterministic timing needed for real-time BMS data exchange.
A dual-contactor architecture uses both a positive main contactor and a negative main contactor. What safety advantage does this provide over a single contactor?
Answer: It isolates the pack from both rails, preventing shock even if one contactor welds shut
If one contactor welds closed, the second one still breaks the circuit on the other rail, ensuring the external load is disconnected from the high-voltage pack.
What characteristic makes NTC thermistors the most common choice for cell temperature sensing in a BMS?
Answer: High resistance that decreases predictably with increasing temperature
NTC (Negative Temperature Coefficient) thermistors exhibit a large, predictable drop in resistance as temperature rises, making them sensitive and inexpensive sensors.
In a BMS stack monitor IC, what is meant by 'flying capacitor' multiplexing?
Answer: A sampling technique where a capacitor connects briefly across each cell to acquire its voltage
Flying capacitor multiplexing connects a small capacitor across each cell in turn, charging to that cell's voltage, then routing it to a common low-voltage ADC for measurement.
Why does a BMS need to know the battery pack's State of Health (SOH)?
Answer: To assess capacity fade and internal resistance increase over the pack's lifetime
SOH tracks how much the pack has degraded from its original capacity and power capability, informing warranty decisions, maintenance schedules, and adaptive SOC limits.
Which component in a BMS architecture is responsible for executing the cell balancing algorithm and issuing balancing commands to slave boards?
Answer: Master BMS controller (BMU)
The Battery Management Unit (master controller) runs the balancing algorithm using data from the CSC slaves and sends back balancing enable signals to the appropriate shunt or switch.
A BMS that supports 'sleep mode' reduces quiescent current draw when the vehicle is parked. Which subsystem is typically kept active during sleep mode?
Answer: Wake-up detection logic and critical cell voltage monitoring
During sleep mode, only the minimal circuitry needed to detect a wake-up event and monitor for dangerous cell voltage extremes remains powered.