Photo: Apple · source ↗Manufacturer device image for this battery profile — not a removed battery.

Phone battery capacity

Apple

iPhone 15 Pro Max

The largest iPhone 15 battery needs about one-third more energy per full recharge than the iPhone 15 Pro.

Direct answer

The iPhone 15 Pro Max battery stores 17.1 watt-hours.

The model-specific battery source lists 17.1Wh, 4,422mAh. Nominal voltage is 3.86V. This technical record says nothing about a UK retailer, GBP price or warranty.

Rated energy: 17.1Wh
Rated capacity: 4,422mAh
Nominal voltage: 3.86V

Power-bank calculation

How many full charges?

We take 75% of the power bank’s rated Wh and divide it by this phone’s 17.1Wh. This is a planning estimate, not a charging guarantee.

5,000mAh class≈ 0.8×

18.5Wh rated → 13.9Wh planned delivery

10,000mAh class≈ 1.6×

37Wh rated → 27.8Wh planned delivery

20,000mAh class≈ 3.2×

74Wh rated → 55.5Wh planned delivery

(power-bank Wh × 0.75) ÷ 17.1Wh

Capacity is not speed

17.1Wh tells you how much.
Charging power tells you how fast.

Wired chargingFast-charge capable with a 20W or higher USB-C adapter

The phone, USB power adapter and cable must negotiate a compatible charging profile. Use certified equipment suitable for the UK 230V/50Hz supply.

Wireless chargingUp to 15W with MagSafe or Qi2; up to 7.5W with Qi

Alignment, heat and charger certification affect real charging power.

Evidence

Two sources with different jobs.

The manufacturer supports the phone and charging claims. The model-specific battery source supplies the figures used in the calculation. These technical figures do not prove UK retail availability or an included charger.

Manufacturer specificationApple specifications ↗Model-specific battery evidenceBattery data via iFixit ↗Sources checked 2026-08-21. We have not physically tested this phone.

Frequently asked

Keep energy and charging power separate.

How many Wh is the Apple iPhone 15 Pro Max battery?

The model-specific source lists 17.1Wh and 4,422mAh. Watt-hours are the useful figure when comparing it with a power bank.

How many times can a 10,000mAh power bank charge the iPhone 15 Pro Max?

A power bank rated around 37Wh provides about 1.6 full charges in this planning calculation. We assume 75% of rated energy reaches the phone battery; actual results vary with cable, temperature and use while charging.

Does 17.1Wh mean the phone charges at 17.1W?

No. 17.1Wh is stored energy. Charging power is a rate measured in watts; the sourced charging description for this model is Fast-charge capable with a 20W or higher USB-C adapter.