Chinese smartphone manufacturers such as Xiaomi, Oppo, and OnePlus have moved toward much larger battery capacities in recent years. However, major global brands like Samsung, Apple, and Google have largely avoided significantly increasing battery sizes in their flagship devices, especially in models sold in the United States.
A new explanation highlights US federal transportation regulations as a key reason behind this trend. According to information shared by well-known tipster Ice Universe on X, lithium battery transport rules under US Federal Regulation 49 CFR 173.185 play a major role in limiting battery size decisions for global smartphone brands.
Under these regulations, lithium-ion battery cells with a capacity of 20 watt-hours or less qualify for simplified transportation and handling. Batteries that exceed this threshold are classified as hazardous goods, requiring stricter packaging, labeling, and documentation. This adds cost, complexity, and logistical challenges for manufacturers shipping devices worldwide.
Smartphone batteries are generally treated as single lithium-ion cells, which means companies must design them to remain within the 20Wh limit to avoid hazardous material classifications. Battery capacity depends not only on milliamp-hours but also on voltage, which typically ranges between 3.7V and 3.85V in smartphones.
Using standard calculations, a 5000mAh battery at 3.85V equals around 19.25Wh, staying just under the limit. However, a 5500mAh battery crosses 21Wh, while a 6000mAh battery exceeds 23Wh. This explains why many flagship phones continue to stay in the 4000mAh to 5000mAh range.
Recent flagship models reflect this pattern. Apple’s iPhone 16 series features batteries between 3355mAh and 4702mAh, translating to roughly 12.75Wh to 17.87Wh. Samsung’s Galaxy S25 lineup ranges from 4000mAh to 5000mAh, while Google’s Pixel 9 series sits close to the limit at around 19.68Wh.
Some manufacturers have found ways around this restriction by using dual-cell battery designs. For example, OnePlus uses two separate battery cells in devices like the OnePlus 13, allowing a combined capacity of 6000mAh while keeping each individual cell under the 20Wh limit, ensuring compliance with transport regulations.
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