CMT CMT Battery & Power Management 3

Question 1

A customer's phone consistently shows 20% battery remaining but then suddenly shuts off. What is the most likely cause?

Accepted Answer

Battery capacity degradation causing inaccurate state-of-charge readings

Answer

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.

Question 2

What is the typical lifespan of a Li-Ion smartphone battery measured in charge cycles before it degrades to approximately 80% of original capacity?

Accepted Answer

300–500 cycles

Answer

Li-Ion batteries in smartphones typically retain about 80% of their original capacity after 300–500 full charge cycles under normal usage conditions.

Question 3

Which factor most accelerates Li-Ion battery degradation over time?

Accepted Answer

Consistently charging to 100% and discharging to 0% combined with high heat exposure

Answer

Extreme charge levels (keeping the battery at 100% or near 0%) combined with heat are the primary accelerators of Li-Ion capacity degradation.

Question 4

What does 'Pass-Through Charging' mean in the context of power banks and mobile devices?

Accepted Answer

Simultaneously charging the power bank while it charges a connected device

Answer

Pass-through charging allows a power bank to receive charge from an input source while simultaneously outputting power to charge a connected device.

Question 5

When replacing a soldered-in (non-removable) smartphone battery, what tool is most essential for safely separating the battery from the device chassis?

Accepted Answer

A heat gun or iOpener to soften adhesive securing the battery

Answer

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.

(CMT) Certified Mobile Tech Practice Test

(CMT) Certified Mobile Tech Practice Test

CMT CMT Battery & Power Management 3