Kepurė AQEX STUBBORN STAMINA LF UPS skirta Raspberry Pi

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• Gamintojas: AQEX
• Modelis: AQEX

Ultra-Durable Industrial LiFePo4 UPS HAT for Raspberry Pi

Official Product Page: https://aqex.eu/stubborn-stamina-lf-raspberry-pi-lfp-ups-hat.html

1. Product Concept & Strategic Advantages

The Stubborn Stamina LF is a high-reliability uninterruptible power supply specifically engineered for long-term industrial deployments. By utilizing LiFePo4 (Lithium Iron Phosphate) technology, it offers superior thermal stability and significantly higher cycle life compared to standard Li-ion solutions.

The device is available for purchase with or without a battery cell, allowing integrators to select the specific capacity required for their application.

Strategic advantages: Industrial Longevity: LiFePo4 chemistry ensures thousands of charge cycles and superior thermal stability. Universal Battery Compatibility: Supports various single-cell (1S) form factors. The modular design allows the use of 18650, 26650, or 32700 cells with matching holders. Flexible Purchasing Options: Available as a standalone unit or bundled with a 26650 LiFePo4 battery as the current standard configuration. High Power Delivery: Specifically designed to handle the peak power demands of the Raspberry Pi 5 (up to 3.5A). * Extreme Reliability: Hardware protection including reverse polarity, deep discharge, and overcharge management.

2. Comprehensive Technical Specifications

• Parameter, Value, Condition / Detailed Notes
• Input Voltage (USB-C), 5.0V – 5.2V, RPi 5 official power adapter compatible
• Output Voltage, 5.0V DC, Precision regulated for Raspberry Pi
• Max Continuous Load, 3.5A, Enhanced current delivery for RPi 5 + Peripherals
• Max Battery Discharge, 7.5A, High-rate discharge capability
• Charging Current, 2A, Fast charging for 18650 LiFePo4 cells
• Battery Chemistry, LiFePo4 ONLY, Nominal: 3.2V / Charging: 3.6V
• Switchover Time, 100 – 300 μs, No-reboot guaranteed transition

> Design Note: The Offline topology ensures almost zero power loss and heat generation during standard operation. A momentary (<1ms) voltage transient occurs during power failure; however, the Raspberry Pi's internal regulation easily filters this, ensuring zero system instability or reboot.

3. qUPS-P-SC User Interfaces and Indicators

4. Battery Management & Protection

• Feature: Specification
• Protection Circuit: Deep discharge, Overcharge, Reverse Polarity
• Thermal Monitoring: Optional NTC connector (5) for temperature-aware charging
• Charging Cut-off: Integrated hardware-level voltage monitoring
• Low Battery Limit: Automatic load disconnection at critical voltage

> Warning: Use only LiFePo4 cells. Connecting standard 3.7V Li-ion batteries may result in incomplete charging or circuit mismatch.

5. User Interfaces & Configuration

5.1 Mode Selection (Switch 4)

• OFF: Complete power cut.
• ON: Immediate power-up when power (battery or external) is available.
• AUTO: Intelligent start-up logic; only boots the Pi when the battery reaches the "Min" energy level.

5.2 GPIO Communication

The system utilizes a 3-pin GPIO interface for OS-level integration. The following pins are used on the 40-pin Raspberry Pi header:

• PFO (Power Fail): GPIO 17 (Pin 11) — Signals external power loss (HIGH = OK / LOW = Backup Mode).
• LIM (Limit): GPIO 27 (Pin 13) — Signals that the battery has reached the critical low threshold.
• SHD (Shutdown): GPIO 22 (Pin 15) — Handshake signal. The UPS cuts power after the OS pulls this pin LOW (or the daemon signals a halt).

6. Visual Diagnostics (LED Indicators)

• LED, Color, Status / Meaning
• External Power (6), Green, Primary 5V power source detected.
• Bad Polarity (9), Red, CRITICAL: Battery installed backwards!
• Full, Green, Battery fully charged (>3.5V).
• Min, Green, Sufficient energy for a safe boot-shutdown cycle.
• Safe, Yellow, Sufficient energy for a safe shutdown cycle.
• Low, Red, Critical level. Immediate shutdown required.

7. Intelligent Power Management (IPM)

• Safe-Start Logic: Prevents "brown-out" loops by ensuring the Pi only starts when the battery can support the peak current of the boot process.
• Shutdown Guard: Monitors the Pi's state and ensures power is only cut after the operating system has safely unmounted the filesystem.
• Input Threshold Tuning: Onboard potentiometer allows adjustment for voltage drops caused by long input cables.

8. Estimated Runtimes (4000mAh LiFePo4)

| Raspberry Pi Model | No Load [min] | 100% Load [min] | | :--- | :---: | :---: | :---: | | Raspberry Pi 2 | 535 | 285 | | Raspberry Pi 3 | 428 | 172 | | Raspberry Pi 4 | 413 | 124 | | Raspberry Pi 5 | 261 | 109 |

*Note: Final runtimes are dependent on battery capacity, age, and ambient temperature.

9. Software Support

• qups-guard: Native daemon for automated monitoring and safe shutdown.
• Compatibility: Fully compatible with Raspberry Pi OS (Debian-based).
• Repository: github.com/aqexhu/qups-guard

HW Version: 1.0 | Released: 2026

Manufacturer: AQEX Electronics | aqex.eu

Specifications