iPhone 18 Pro Max Caps Its Own Battery Below 20Wh to Clear Shipping Rules

Teardowns cited by TechRadar show a 5,567mAh battery in eSIM-only models and a 5,391mAh cell in versions with a physical SIM slot. Both exceed 20Wh, the threshold at which most countries add shipping requirements for devices with a single-cell battery. The United States and the United Kingdom classify such devices as dangerous goods and bar them from standard consumer mail services, including USPS standard post and Royal Mail, which complicates both direct-to-customer orders and deliveries to retail stores.

Prepare to Ship addresses that by using battery firmware to limit capacity to under 20Wh. According to TechRadar, the mode is active from the moment the phone is manufactured until a customer first activates it, after which the limit lifts automatically. The phone the buyer ends up using is not restricted.

Owners who later send the device elsewhere, whether for repair or resale, must enable the mode themselves through Settings, then General, Transfer or Reset iPhone, then Prepare to Ship, and follow the onscreen instructions, including choosing whether to erase the phone. TechRadar notes the battery may need to discharge before the mode engages, so the charger should be unplugged, and the handset may run warmer than usual during the process. The step can take anywhere from a few minutes to several hours depending on how far the battery has to drop, though the phone remains usable in the meantime if it has not been erased. When the preparation is complete, the Settings app shows a red badge reading Ready to Ship; if the phone was erased, the status instead appears on the Hello screen after tapping the information button.

Once enabled, the mode limits the battery to under 80% capacity for 14 days. To reverse it earlier, users go to Settings, then General, Transfer or Reset iPhone, then Ready to Ship, and tap Undo Shipping Preparation.

TechRadar reports that the approach may spread beyond this model. Future large iPhones are expected to carry the same feature, and Android manufacturers could adopt it as well, since it offers a straightforward way around the 20Wh threshold. Some Android phones currently avoid the restriction by splitting capacity across multiple smaller battery cells, but a single-cell design can make a firmware-based limit the more practical option.