CMT Battery & Power Management Flashcards
7 cards from real CMT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 CMT Battery & Power Management flashcards as text
A customer's phone consistently shows 20% battery remaining but then suddenly shuts off. What is the most likely cause?
Answer: Battery capacity degradation causing inaccurate state-of-charge readings
As Li-Ion batteries age and lose capacity, the fuel gauge calibration becomes inaccurate, causing the device to report incorrect remaining charge and shut down unexpectedly.
What is the typical lifespan of a Li-Ion smartphone battery measured in charge cycles before it degrades to approximately 80% of original capacity?
Answer: 300–500 cycles
Li-Ion batteries in smartphones typically retain about 80% of their original capacity after 300–500 full charge cycles under normal usage conditions.
Which factor most accelerates Li-Ion battery degradation over time?
Answer: Consistently charging to 100% and discharging to 0% combined with high heat exposure
Extreme charge levels (keeping the battery at 100% or near 0%) combined with heat are the primary accelerators of Li-Ion capacity degradation.
What does 'Pass-Through Charging' mean in the context of power banks and mobile devices?
Answer: Simultaneously charging the power bank while it charges a connected device
Pass-through charging allows a power bank to receive charge from an input source while simultaneously outputting power to charge a connected device.
When replacing a soldered-in (non-removable) smartphone battery, what tool is most essential for safely separating the battery from the device chassis?
Answer: A heat gun or iOpener to soften adhesive securing the battery
Heat guns or iOpener heating pads soften the adhesive holding the battery to the chassis, allowing safe removal without puncturing or bending the battery cell.
Which charging behavior is recommended to maximize long-term Li-Ion battery health?
Answer: Keep battery between 20–80% charge and avoid prolonged exposure to high heat while charging
Keeping Li-Ion batteries between 20–80% charge and avoiding heat minimizes electrochemical stress, reducing capacity degradation over hundreds of charge cycles.
What is the purpose of the 'constant voltage' (CV) phase in a Li-Ion battery charging cycle?
Answer: To taper the current as the battery approaches full charge to prevent overcharging
During the CV phase, the charger maintains a fixed voltage while current tapers off, safely bringing the battery to full charge without causing damage from overcharging.