Why Battery Percentage Is Often Wrong
Many power banks show a percentage — but that doesn’t mean it’s accurate.
This article is part of the Power Bank Knowledge Hub and supports the High-Power Power Banks: A Complete Technical Guide.
Most low-cost designs still rely on voltage-based estimation, which breaks down under:
- High current discharge
- Fast charging protocols
- Temperature changes
- Battery aging
At high power, this can cause sudden shutdowns even when “30%” is displayed.
Voltage Display: Cheap and Inaccurate
Voltage-based estimation works by:
- Measuring battery voltage
- Comparing it to an OCV lookup table
Problems:
- Voltage drops under load
- Temperature alters readings
- Aging changes battery behavior
This method is acceptable only for low-power products.
Fuel Gauge: How Accurate Power Banks Work
A real fuel gauge IC uses:
- Coulomb counting (current integration)
- Voltage correction
- Temperature compensation
- Battery aging models
This allows accurate estimation of:
- State of Charge (SoC)
- Remaining runtime
- Cycle count and health trends
Why Fuel Gauges Are Essential Above 60W
High-power power banks experience:
- Rapid current changes
- PD renegotiation
- Multi-port load balancing
Without a fuel gauge:
- Display data becomes unreliable
- Thermal protection may lag
- User trust collapses
That’s why premium brands invest in dedicated fuel gauge ICs.
Reachinno’s Approach
Reachinno integrates fuel gauges as part of the core battery management system, not as an add-on.
This ensures:
- 1% SoC resolution
- Stable performance under PD load
- Long-term reliability
Knowledge Hub Reference
This article belongs to the High-Power Power Bank pillar.
➡️ Read the complete guide: High-Power Power Banks: A Complete Technical Guide
