220-1101 Mobile Devices Practice Question
A user's Android smartphone exhibits a strange charging behavior. When the phone is powered off and connected to the wall charger, it charges normally and the battery percentage increases. However, when the phone is powered on and plugged into the same charger, the device shows the charging icon, but the battery percentage steadily decreases over time, eventually causing the phone to shut down. The user has already tried different charging cables and adapters, and has performed a factory reset. Which component is MOST likely faulty?
⚠ Common exam trap
The 220-1101 exam often tests the distinction between a component that works under no load but fails under load, leading candidates to incorrectly suspect the PMIC or charging port when the battery's increased internal resistance is the root cause.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Battery
The battery is most likely faulty because it can hold a charge when the phone is off (minimal current draw) but fails under the higher load of the powered-on system. A degraded battery's internal resistance increases, causing voltage sag under load, which the PMIC interprets as a low charge state, leading to a net discharge despite the charger being connected.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Battery
Why this is correct
An aging or failing battery often cannot accept charge fast enough to keep up with the phone's power consumption while running, leading to a net decrease in charge level even though a charging current is detected.
- ✗
Charging port / USB connector
Why it's wrong here
A faulty charging port or USB connector typically causes physical, intermittent, or power-delivery problems that persist regardless of whether the phone is powered on or off — for example, a loose solder joint, bent pin, or damaged flex cable. Since this device charges normally when completely powered off, the port and its cable connection can reliably transfer current to the PMIC, so it cannot be the root cause. The symptom of a net battery drain while on, yet a successful charge when off, points to an inability of the battery itself to absorb charge under a simultaneous system load.
- ✗
Power management integrated circuit (PMIC)
Why it's wrong here
The power management integrated circuit (PMIC) is responsible for converting wall/USB power into the correct charging voltage and current for the battery, and for routing power to the system — a failure there would typically cause a complete inability to charge, erratic voltage spikes, overheating, or random shutdowns in both power states. Here, charging succeeds while the phone is off, proving the PMIC's charging path, voltage regulation, and safety cutoffs are functioning correctly. A subtle nuance: when the device is on, the PMIC still feeds the battery, but if the system load exceeds the charger's supply, the battery must supplement the deficit; a healthy battery can do this without its state of charge dropping, whereas an aged battery cannot.
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Operating system battery calibration
Why it's wrong here
Operating system battery calibration concerns the fuel-gauge software that estimates remaining capacity from battery voltage and internal resistance, not the actual physical flow of electrons into the cell. An uncalibrated OS typically shows erroneous percentage readings, sudden jumps to 1% or 100%, or an early shutdown, but it cannot cause a real, measured net decrease in charge level while the phone is plugged in. Moreover, the user already performed a factory reset, which clears software battery stats, yet the condition persisted — ruling out any OS-level calibration data. The observed discharge is a real hardware event, specifically the battery's reduced ability to accept charge (higher internal resistance) under load.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 220-1101 practice question is part of Courseiva's free CompTIA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 220-1101 exam.