Apple has implemented a clever firmware workaround to allow the iPhone 18 Pro Max's oversized battery to comply with international air transport regulations. The battery exceeds 20 Wh—the limit many countries set for single-cell batteries on aircraft—so Apple reduces its reported capacity via software during manufacturing and shipping.
Once a user activates the device for the first time, the limitation is removed and the full battery capacity becomes available: 21.06 Wh or 21.75 Wh depending on the model. This approach lets Apple ship the phone globally without violating freight rules while delivering maximum battery life to customers once they receive it.