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IEC TS 62393: Battery Run-Time Measurement for Portable Multimedia Equipment
Standardised Testing Methodologies for Mobile PC and Handheld Device Battery Life Evaluation
1. Overview of IEC TS 62393
IEC TS 62393 is a Technical Specification that defines standardised battery run-time measurement methods for portable and hand-held multimedia equipment, with particular emphasis on mobile personal computers. Published by IEC Technical Committee 100 (Audio, video and multimedia systems and equipment), this standard addresses a critical problem: the lack of consistent, comparable battery life metrics across different manufacturers and device categories.
The specification defines two complementary measurement methods that, when averaged, provide a realistic estimate of battery run-time under mixed usage patterns. Method (a) measures continuous MPEG video playback from a hard disk at a display luminance of 20 cd/m2, representing multimedia-intensive usage. Method (b) measures idle desktop display at minimum LCD luminance, representing low-power usage. The final run-time is calculated as the arithmetic mean of the two measurements, rounded down to one decimal place.
The dual-measurement approach in IEC TS 62393 is ingeniously practical: no single workload can represent the diversity of real-world usage patterns. By averaging a high-load video test with a low-load idle test, the result better reflects the mixed-use scenarios that typical mobile users experience daily.
2. Measurement Methods in Detail
| Parameter | Method (a) — Video Playback | Method (b) — Idle Desktop |
|---|---|---|
| Display luminance | 20 cd/m2 minimum (white area) | Lowest possible setting |
| Workload | Continuous MPEG-1 video playback from HDD (320 x 240) | Static desktop screen display |
| Audio | Minimum or mute | Mute |
| Backlight / Screen | On throughout test | On throughout test; never set to off |
| Power management | Must not cause frame drops | Lowest configurable values; must disclose settings |
| Hard disk drive | Active throughout (file read from HDD) | May power off during test |
| Battery end condition | Not defined (manufacturer discretion) | Not defined (run until empty or system-defined threshold) |
| Foreground applications | Movie player only | None (clean desktop) |
| Background applications | Not defined; disclose changes from defaults | Not defined; disclose changes from defaults |
A critical detail often overlooked by test engineers: Method (a) requires the movie file to be stored on and played back directly from the hard disk. If the operating system caches the entire file in main memory — common with small video files — the power draw during the test will be artificially low because the HDD can enter a low-power state. To prevent this, the standard recommends linking the file repeatedly so the total size exceeds available main memory.
The specification allows manufacturers to disclose settings that differ from factory defaults. This transparency requirement is essential for reproducibility: without knowing whether power management features (CPU throttling, display dimming, Wi-Fi power saving) were modified, the test results cannot be meaningfully compared between different products or between a manufacturer’s published figure and an independent reviewer’s measurement.
3. Engineering Design Insights for Battery Run-Time Optimisation
3.1 Display Power Management
The display subsystem is typically the largest single power consumer in portable multimedia devices, accounting for 30-50% of total system power under typical usage. IEC TS 62393’s choice of 20 cd/m2 as the reference luminance for Method (a) is not arbitrary — it represents the approximate minimum usable luminance for indoor video viewing. Engineers designing for long battery life should focus on three display-related levers:
- Backlight efficiency: LED backlights have improved from approximately 50 lm/W (2010 era) to over 150 lm/W in current-generation displays. A local dimming architecture with multiple LED zones can further reduce backlight power by 30-50% during video playback with dark scenes.
- Panel transmissivity: Each percentage point improvement in LCD panel transmissivity translates to a corresponding reduction in backlight power for the same perceived brightness. Oxide TFT (IGZO) and LTPS backplanes offer higher aperture ratios than conventional a-Si TFT.
- Content-adaptive brightness: Dynamic backlight control that adjusts to the video content’s average picture level (APL) can reduce display power by 20-40% without perceived quality degradation.
3.2 Storage Subsystem Optimisation
IEC TS 62393’s Method (a) explicitly tests hard disk-based video playback. For systems using solid-state drives (SSDs) or flash storage, the power profile is fundamentally different. An SSD consumes 0.5-2 W during active read operations versus 3-6 W for a spinning HDD, and the idle power for an SSD can be as low as 0.05 W (deep sleep) compared to 0.5-1 W for an HDD. When testing systems with SSDs, engineers should note that the power advantage of SSDs means Method (a) results will be significantly higher than on HDD-based systems with otherwise identical specifications. The standard permits the use of secondary memory such as flash storage when no hard drive is present in the system.
3.3 CPU and Platform Power Management
The measurement methodology implicitly tests the effectiveness of the platform’s power management infrastructure. Modern CPUs implement multiple power states (C-states for idle, P-states for performance) and the operating system’s scheduler controls transitions between these states. Key engineering considerations include:
- Idle power floor: Method (b) essentially measures the system’s idle power plus display power. A well-optimised platform should achieve package C-state residency >90% during idle desktop operation. If the measured time in Method (b) is unusually low, it often indicates a driver or background process preventing deep C-state entry.
- Video decode efficiency: Method (a) benefits from hardware-accelerated video decode. A system using software decode can consume 5-10 W of CPU power for MPEG-1 playback, while hardware decode typically consumes <1 W. This is a critical design consideration for fanless systems where sustained CPU load may also trigger thermal throttling.
When designing for IEC TS 62393 compliance, prioritise the display subsystem (largest power consumer), ensure hardware video decode is enabled and tested, and validate that platform idle power states are properly configured. A typical well-optimised notebook should achieve Method (a) times of 4-6 hours and Method (b) times of 10-14 hours under the standard’s test conditions.
4. Frequently Asked Questions
Q1: Why does IEC TS 62393 use 20 cd/m2 as the reference luminance?
20 cd/m2 was chosen as the minimum luminance level that allows acceptable indoor video viewing. It represents a conservative test condition that maximises battery run-time while remaining representative of real-world dark-environment usage. Manufacturers may test at higher luminance but must disclose the actual setting used.
Q2: Can manufacturers round up the measured run-time?
No. The standard explicitly requires rounding downward to one decimal place. For example, a calculated result of 5.683 hours must be reported as 5.6 hours, not 5.7 hours. The standard permits the use of the term “approximately” or “about” but does not allow rounding in the favourable direction.
Q3: How does the standard account for battery ageing?
The standard does not specify a required condition for the test battery (degree of degradation). This is left to each manufacturer’s discretion, with the recommendation that their guidelines be followed. For fair comparisons, a fresh battery (less than 50 charge cycles) calibrated according to the manufacturer’s procedure should be used.
Q4: Is the measurement method applicable to tablets and smartphones?
While the standard was written primarily with mobile PCs in mind, its scope extends to “portable and hand-held multimedia equipment” generally. The same dual-method approach can be applied to tablets and smartphones, though the test conditions (display luminance, playback size of 320 x 240) may need adaptation for smaller screens and different form factors.
