The core demands of vehicle-mounted portable power supplies focus on "portability, civilian compatibility, and cost-effectiveness". The selection of power supply system is not arbitrary, but the optimal outcome derived from comprehensive considerations of global power supply standards, equipment characteristics, and actual application scenarios. Currently, the mainstream power supply systems worldwide fall into three categories: single-phase AC supply, split-phase supply, and three-phase AC supply, each tailored to distinct application scenarios. Among them, single-phase AC supply has emerged as the primary choice for current vehicle-mounted portable power supplies, thanks to its seamless alignment with the core requirements of mobile power supply.

These products boast an extensive range of applications, covering not only RV power supply and portable photovoltaic (PV) supporting systems (such as energy storage power supply for outdoor PV panels), but also outdoor camping, vehicle emergency power supply, temporary construction site electricity, outdoor live streaming, and emergency power for small businesses. Essentially, they serve as mobile civilian power supply terminals. An analysis of actual application scenarios reveals that the power consumption of vehicle-mounted portable power supplies is predominantly for small-power civilian use, which dictates that their power supply system must cater to civilian needs rather than complex industrial-grade power supply systems.

Looking at both the domestic market and overseas export trade, single-phase AC power has consistently maintained a dominant position in the vehicle-mounted portable power supply market. Its core advantage lies in its perfect compatibility with the 110V/220V civilian voltage standards adopted in most regions worldwide, supporting the vast majority of civilian electrical appliances. Whether it is refrigerators, air conditioners, or induction cookers installed in RVs, daily lighting equipment, mobile phone charging piles, or even small household appliances and emergency devices adapted for overseas markets, most operate on a single-phase system. This eliminates the need for additional conversion equipment, effectively avoiding power supply incompatibility issues and significantly enhancing the versatility and practicality of vehicle-mounted portable power supplies. Additionally, most single-phase AC power supply devices feature a simple structure, small size, and light weight. Whether placed inside an RV, carried for outdoor camping, or kept as a vehicle emergency backup, they impose no extra burden on use. They also require no complex installation or wiring, allowing ordinary users to operate them effortlessly without professional expertise.

In contrast, three-phase AC supply is primarily designed for industrial-grade high-power supply. Adopting a three live wires + one neutral wire configuration, it offers high power output and strong stability. However, the equipment is bulky and involves high investment costs, making it completely unsuitable for vehicle-mounted portable power supply scenarios centered on small-power civilian use. Even from the perspective of "portability" alone, three-phase supply is impractical. Furthermore, its procurement and maintenance costs are significantly higher than those of single-phase supply. For vehicle-mounted scenarios with power requirements ranging from a few hundred watts to 3kW, three-phase supply is a clear case of over-engineering, hence its rare adoption in the industry.

Split-phase supply, on the other hand, is mainly compatible with the 120V/240V dual voltage standard in American regions (including the United States, Canada, Mexico, etc.). Featuring a two live wires + one neutral wire design, it can simultaneously provide 120V low-power and 240V medium-power supply, meeting the needs of both small-supply civilian electrical appliances and medium-supply equipment. It is therefore the exclusive power supply system for local vehicle-mounted portable power supplies. The key reason split-phase supply is preferred over three-phase AC supply in American regions is that it balances the needs of both small and medium-power devices while avoiding the bulkiness and high costs of three-phase equipment, aligning with the core attributes of "mobility and portability" for vehicle-mounted portable power supplies. However, split-phase power has obvious limitations: it is only applicable to specific regions in the Americas, does not comply with power standards in most parts of the world, and involves higher equipment complexity and costs than ordinary single-phase AC power. As a result, it is only used in American export scenarios and not adopted for vehicle-mounted portable power supplies in most global regions.

It is important to clarify that the preference for single-phase AC power in vehicle-mounted portable power supplies is not a technical compromise, but a rational decision based on scenario-specific needs, independent of the inherent advantages or disadvantages of other systems. Single-phase AC power has become the mainstream because it strikes the optimal balance between compatibility, portability, and cost. It can directly connect to the vast majority of civilian electrical appliances without additional conversion devices; its size and weight are suitable for both vehicle and outdoor scenarios; and it features a low maintenance threshold, enabling easy operation by ordinary users. In contrast, split-phase power is limited by regional standards, while three-phase AC power is constrained by power and cost considerations. Neither can meet the multi-scenario and global application needs as effectively as single-phase AC power.

In summary, the dominance of single-phase AC power as the preferred choice for vehicle-mounted portable power supplies is the result of the combined effects of multiple factors, including market demand, user experience, and industry development. This choice not only adheres to the fundamental principles of civilian mobile power supply but also points the way for the future development of vehicle-mounted portable power supplies — taking users' actual needs as the guide to find the optimal balance between practicality and convenience.