Real-World Testing of Lithium Battery Capacity: Methods and Insights

Verifying Claimed Battery Capacity with DIY Methods

Lithium-ion batteries are ubiquitous in modern electronics, and their stated capacities significantly influence user experience. This article delves into a real-world scenario of testing a battery’s capacity and analyzing power consumption under various conditions.

Battery Capacity Test
A battery labeled with a capacity of 3800mAh was tested using a self-designed constant-current discharge circuit. Results indicated a capacity of approximately 1700mAh—far below the claimed value. Key aspects of the test include:

Conditions

Ambient temperature: 16°C
Standard followed: GB/T18287-2000
Testing Process

Ensured initial voltage was 4.17V before discharging.
Recorded discharge duration until the terminal voltage reached 2.75V.
Calculated capacity based on the current-time graph.
Sources of Error

Variability in the constant-current circuit due to temperature fluctuations.
Discharge current slightly exceeded the standard, leading to a conservative estimate of capacity.
Phone Power Consumption Analysis
Using an MF47 multimeter, power consumption was measured in various operational modes, including standby and active use.

Key Findings:

Shutdown current: 1.0mA
Standby current in CDMA mode: fluctuating between 3–25mA
GSM mode call current: approximately 250mA
Insights:

Impact of Operational Modes
GSM mode consumes more power than CDMA mode during network interactions.

Effect of Screen Brightness
Power consumption increases significantly with brightness, from 41mA at low to 153mA at high brightness.

Dual-Mode Power Draw
Dual SIM standby consumes more power than single SIM, but single SIM’s power draw remains stable across modes.