The iPhone Duo carries two separate battery cells with a combined 4,883 mAh, according to the first teardown videos from the YouTube channels REWA Technology and Phone Repair Guru.
The larger cell is rated at 2,962 mAh (11.56 Wh) and the smaller at 1,921 mAh (7.5 Wh). Milliamp-hours measure charge, while watt-hours also account for voltage, which makes them the better figure for comparing phones. Together the cells come to 19.06 Wh, with the bigger one supplying about 61 percent. Both are held in by electrically activated adhesive, a glue that lets go when electricity is applied.
REWA Technology's video includes a labeled breakdown of the logic board, the main circuit board, which holds Apple's A20 Pro chip and C2 cellular modem, among other parts. Phone Repair Guru said the Touch ID button can technically be removed for repairs, though the channel called the process difficult. It also said the charging port is apparently a fully modular USB-C unit, meaning it can be swapped as its own part. The phone is eSIM-only worldwide, so there is no physical SIM card to remove at all.
Two videos do not add up to a repair verdict, but they sketch a mixed picture. A battery that releases on demand and a port that is its own module point toward easier service. A Touch ID button that fights back points the other way. The split battery adds one more consideration: repairers now deal with two cells of different sizes rather than one.
The repair site iFixit will likely publish a more detailed teardown in the coming days. The question there is how it weighs the easy battery and port against that stubborn fingerprint button.