Outdoor Power Supply Over-Discharge:Comprehensive Interpretation of Hazard Mechanisms, New Industry Regulations, and Protection Technologies

Outdoor Power Supply Over-Discharge:

Comprehensive Interpretation of Hazard Mechanisms, New Industry Regulations, and Protection Technologies

1. What is "Over-Discharge" in Outdoor Power Supplies?

The core energy storage units of outdoor power supplies (also known as portable energy storage power supplies) are typically Lithium Iron Phosphate (LiFePO4) or NCM ternary lithium battery cells. "Over-discharge" refers to the phenomenon where the battery voltage is discharged far below its safe lower limit (typically below 2.0–2.5V per cell for LiFePO4 cells), causing irreversible changes in the structure of the positive and negative electrode materials. Unlike consumer electronics such as smartphones and laptops, outdoor power supplies feature large capacities and complex application scenarios (such as long-term idle storage during camping, vehicle-mounted low-temperature storage, and continuous discharge when connected to micro-power devices). As a result, the risk of over-discharge is easily overlooked.

Common triggers include: "trickle depletion" caused by continuously powering micro-power devices such as routers, sensors, and cameras for extended periods; prolonged disuse without regular recharging; increased internal resistance in low-temperature environments where usable voltage is misjudged as "power remaining" and continued to be used; and unreasonable protection threshold settings or protection circuit failures in some older BMS (Battery Management System) models.

Figure 1: Lithium-ion battery discharge curve and over-discharge protection thresholds — Voltage plunges rapidly in the low-power region, requiring protection circuits to cut off in time before the drop.

2. Hazards of Over-Discharge: Far Beyond "Fewer Uses"

2.1 Irreversible Damage at the Electrochemical Level

Excessively low voltage causes oxidative dissolution of the negative current collector (copper foil). Copper ions migrate and deposit on the surface of the negative electrode during subsequent charging, forming micro-short circuits. Simultaneously, the crystal lattice structure of the positive electrode material may collapse. Together, these factors cause permanent capacity degradation, which cannot be fully recovered through methods like "slow charging" or "activation."

2.2 Significantly Increased Safety Risks

• Increased internal micro-short circuits lead to abnormal local heat generation during charging, which may induce thermal runaway in extreme cases.
• Cell swelling and a sudden jump in internal resistance impair the stability of high-power output.
• Recharging after over-discharge without "pre-charge awakening" protection may cause secondary damage to the battery cells.

2.3 Degradation of User Experience

Even if the battery is not rendered completely useless after over-discharge, it frequently exhibits issues such as a widening gap between nominal capacity and actual usable capacity, faster power drop in low-temperature environments, and more pronounced voltage sags during high-power output, directly affecting the reliability of outdoor power supplies in emergency and camping scenarios.

Figure 2: Impact trend of long-term over-discharge idling on battery capacity retention (Specific values vary across products due to different cell systems and protection strategies; shown for illustration purposes only).

3. Latest Industry Dynamics: Official Implementation of National Mandatory Standards

On March 31, 2026, the mandatory national standard "Safety Technical Specification for Mobile Energy Storage / Power Banks" (GB 47372—2026), formulated under the organization of the Ministry of Industry and Information Technology, was officially published. It will take effect on April 1, 2027, with a 12-month transition period. This is China's first dedicated mandatory national standard in the field of mobile energy storage (covering power banks and outdoor power supplies), marking a transition from previous reliance on generic lithium battery standards to a new era of "dedicated specifications + full-chain control."

The new national standard imposes comprehensive strict requirements across critical stages, including intrinsic cell safety, circuit protection, overcharge/overdischarge protection, short-circuit protection, and temperature control. It introduces mandatory test items such as nail penetration, thermal abuse (135°C constant temperature for 60 minutes), and 1.2-meter drop tests. The overcharge test voltage is raised to 1.3 times the charge limit voltage, and the flame retardancy rating of the enclosure is upgraded from V-1 to V-0.

Regarding over-discharge protection, the new regulations explicitly require products to feature dual protection circuits that automatically lock out charge and discharge functions when key parameters such as voltage and temperature become abnormal, preventing operation under faulty conditions. Additionally, the Battery Management System (BMS) is required to monitor parameters like voltage and temperature in real time and possess the capability to store and read exception data for easy traceability of over-discharge events. Furthermore, the standard mandates labeling the "Recommended Safe Service Life," reminding users to replace aging battery cells in time, thereby indirectly reducing the likelihood of protection failure and over-discharge damage caused by cell aging.

Notably, the formulation of the new national standard relies on the technical expertise of multiple leading domestic cell manufacturers, covering the primary production camps of mobile power cells. This means that design baselines for over-discharge and overcharge protection logic in future outdoor power supplies will become more standardized and transparent. Consumers will also be able to verify cell sources and safety levels via product labels and traceability codes.

4. Mainstream Protection Technologies: How Three-Tier Protection Operates Synergistically

To mitigate over-discharge risks, current mainstream outdoor power supplies generally adopt a three-tier protection architecture consisting of "Cell-Level — Circuit-Level — System-Level" protection. These three tiers work in synergy to complete protective actions before the voltage drops below the safety threshold.

Figure 3: Schematic diagram of a typical three-tier over-discharge protection architecture for outdoor power supplies.

4.1 Cell-Level: Intrinsic Safety Design

Starting from the cell material system, LiFePO4 cells offer superior over-discharge tolerance and thermal stability compared to NCM ternary lithium cells, making them the mainstream choice for outdoor power supplies today. Some manufacturers also integrate temperature and pressure sensing structures inside the cells to provide early warning signals for circuit-level protection.

4.2 Circuit-Level: BMS Real-Time Monitoring and Multi-Stage Cut-Off

BMS is the core execution layer for over-discharge protection. By collecting real-time voltage, current, and temperature data, it triggers a staged response as the voltage approaches the safe lower limit: first shedding non-essential loads and issuing low-battery alerts; if the voltage continues to drop, it directly cuts off the output ports to prevent the cell from being dragged into the damage zone.

4.3 System-Level: Deep Sleep and Remote Early Warning

Once protection is triggered, the system typically enters a deep sleep mode, controlling self-power consumption at an ultra-low level (microampere level for select models) to delay further voltage drop as much as possible. Models with APP connectivity can also push alerts to user smartphones when power is critically low and record event logs for subsequent troubleshooting and after-sales evaluation.

5. User Usage Recommendations

• Recharge the battery to approximately 40%–60% before long-term storage, which is more conducive to cell health than storing it fully charged or completely empty.
• Avoid continuously powering micro-power devices that consume power constantly (such as always-on routers and cameras) over long periods to prevent "stealth over-discharge."
• Perform a recharge check on idle outdoor power supplies every 1 to 3 months, paying special attention to actual voltage performance in low-temperature winter environments.
• When purchasing, verify whether the product features a comprehensive BMS protection and deep sleep mechanism, and check if it complies with or benchmarks against the latest safety specifications such as GB 47372-2026.
• If the power supply exhibits conditions such as inability to charge normally after over-discharge, swelling, or abnormal heating, stop using it immediately and contact after-sales service. Do not attempt to disassemble or forcibly charge it yourself.

Conclusion

Over-discharge is a frequently overlooked issue during long-term use of outdoor power supplies, yet it has far-reaching effects on battery life and safety. With the official implementation of dedicated mandatory national standards like GB 47372-2026, industry thresholds for key safety indicators such as over-discharge and overcharge will be further elevated, and multi-tier protection architectures will continue to evolve. For users, understanding the causes and hazards of over-discharge and developing good storage and usage habits are equally indispensable for extending equipment lifespan and ensuring outdoor electricity safety.

Sources / References:

Announcements by the Ministry of Industry and Information Technology and the Standardization Administration of China; "Safety Technical Specification for Mobile Energy Storage / Power Banks" (GB 47372-2026) and official public interpretations. Values such as capacity retention rates in this document are for illustrative purposes; specific performance is subject to actual product testing and authoritative test reports.