CMT CMT Battery & Power Management 1 — Questions and Answers
Question 1: Which battery chemistry is most commonly used in modern smartphones and tablets?
- Nickel-Metal Hydride (NiMH)
- Lithium-Ion (Li-Ion) (Correct answer)
- Nickel-Cadmium (NiCd)
- Lead-Acid
Correct answer: Lithium-Ion (Li-Ion)
Lithium-Ion batteries are the standard in modern mobile devices due to their high energy density, low self-discharge rate, and lack of memory effect.
Question 2: What is the primary advantage of Lithium-Polymer (LiPo) batteries over standard Li-Ion batteries in mobile devices?
- Higher voltage output
- Flexible form factor allowing thinner device designs (Correct answer)
- Faster charge times at all temperatures
- Lower manufacturing cost
Correct answer: Flexible form factor allowing thinner device designs
LiPo batteries use a polymer electrolyte instead of liquid, allowing them to be manufactured in flexible, thin, and custom shapes that enable slimmer device designs.
Question 3: A customer reports their phone battery drains much faster in cold weather. What is the most likely cause?
- Software update corrupting battery calibration
- Cold temperatures reduce chemical reaction efficiency in Li-Ion cells (Correct answer)
- Cold weather increases screen brightness automatically
- The battery management IC is defective
Correct answer: Cold temperatures reduce chemical reaction efficiency in Li-Ion cells
Cold temperatures slow the electrochemical reactions within Li-Ion cells, temporarily reducing available capacity and increasing internal resistance.
Question 4: What does the term 'battery capacity' refer to in mobile devices?
- The maximum voltage the battery can output
- The total charge a battery can store, measured in milliamp-hours (mAh) (Correct answer)
- The number of full charge cycles a battery can complete
- The physical size of the battery cell
Correct answer: The total charge a battery can store, measured in milliamp-hours (mAh)
Battery capacity is expressed in milliamp-hours (mAh) and represents the total amount of electrical charge the battery can store and deliver.
Question 5: Which Qualcomm charging standard delivers rapid charging by negotiating higher voltage and current between the charger and device?
- USB Battery Charging 1.2
- Quick Charge (QC) (Correct answer)
- Trickle Charge Protocol
- Adaptive Voltage Scaling
Correct answer: Quick Charge (QC)
Qualcomm Quick Charge negotiates increased voltage and/or current via the USB connection, allowing compatible devices to charge significantly faster than standard USB charging.
Question 6: What is 'battery memory effect' and which battery chemistry is most susceptible to it?
- Permanent capacity loss from overcharging; most common in Li-Ion
- Reduced capacity from repeated partial discharges; most common in NiCd (Correct answer)
- Swelling from heat exposure; most common in LiPo
- Voltage drop from age; most common in Lead-Acid
Correct answer: Reduced capacity from repeated partial discharges; most common in NiCd
Memory effect occurs in Nickel-Cadmium batteries when they are repeatedly partially discharged before recharging, causing the battery to 'remember' the lower capacity.
Question 7: A technician notices a mobile device battery is visibly bulging. What is the correct course of action?
- Charge the battery fully and test device performance
- Puncture the battery to release built-up gas safely
- Replace the battery immediately as it poses a fire and explosion risk (Correct answer)
- Place the device in direct sunlight to normalize the swelling
Correct answer: Replace the battery immediately as it poses a fire and explosion risk
A swollen battery indicates gas buildup from internal chemical breakdown and poses serious fire and explosion risks; the battery must be replaced immediately and disposed of properly.
CMT CMT Battery & Power Management 1
Which battery chemistry is most commonly used in modern smartphones and tablets?