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WattCase Slim 3600 battery case in black on an iPhone 17 Pro Max
iPhone 17 Pro Max · Black · front and back

Slim charging case for iPhone 13–17 · 3600 mAhSlim 3600

The case is the battery. 3,600 mAh rated and 3,500 mAh measured on every model, Pro Max included — the most capacity we fit in the 15.5 mm Slim shell, delivered through a Qi coil.

$64 / unit · retail

Colour

Capacity

Fits

iPhone 17 · 3,600 mAh rated / 3,500 mAh measured · adds up to 53%

3,500mAh

Measured capacity

53%

Added to this model

95g

Case weight

The detail sheet, in English

Six things the render cannot tell you.

Slim 3600 case in orange shown front and back

01 / ONE PIECE

The shell is the battery. There is no second device.

A 3,600 mAh cell is laminated into the back plate on every model, so the phone and the power share one outline. Nothing snaps off in a bag, nothing stays on the desk when you leave.

Engineer measuring a wireless charging coil with a power meter

02 / COIL

15 W that holds, not 15 W on a spec sheet.

One coil, aligned on a jig to ±0.2 mm, driven by a controller that keeps 15 W until the phone's own thermal limit takes over. Every unit is measured on the bench before packing.

Inspector checking a case with digital calipers

03 / STRUCTURE

0.8 mm camera bezel. 1.2 m drop. Matte TPU over a PC frame.

The camera sits inside a raised bezel instead of behind a hole, and the frame is moulded per model — the 17 and the 16 do not share a shell.

Slim 3600 in black, back view with LED indicator

04 / READOUT

Four dots, one button, no guessing.

Press once and the four-dot indicator shows what is left in quarters. Hold for two seconds to switch the coil off when you want to run on the phone's own cell.

Charging and aging test racks in the factory

05 / HEAT

38–42°C, then it steps down instead of pushing.

An NTC sits against the cell. Above 45°C the controller drops to 7.5 W, which is why our numbers look lower than a listing that never measured temperature at all.

Slim 3600 in navy on an iPhone 17 Pro Max

06 / FIT

Fifteen models, seven moulds, one mounting method.

Slide the phone in from the top, press the corners, done. The same gesture works across the 13 to the 17 — only the mould changes, which is why a new iPhone costs us a mould and not a new product line.

Full specification

Everything, including the numbers we lose.

Slim 3600 · measured in-house
Fits iPhone 17
Cell Li-polymer 3.7 V · rated 3,600 mAh / measured 3,500 mAh · all models
Charge added about 53% on iPhone 17
Wireless output Qi 15 W max · steps to 7.5 W above 45°C
Wired output USB-C 22.5 W max · bidirectional pass-through
Input USB-C 5 V/3 A, 9 V/2 A
Case weight · iPhone 17 93–115 g
Dimensions 152.5 × 75 × 15.5 mm
Materials Matte TPU over PC frame · raised 0.8 mm camera bezel
Cycle life ≥80% capacity at 500 cycles
Protection 1.2 m drop tested · 0.6 mm screen lip
Documents UN 38.3 · IEC 62133 · SDS · sea & air transport
Carton 80 pcs · 15–16.5 kg gross · carton 535 × 382 × 225 mm · colour box 183 × 103 × 25 mm, 88 g