Maximizing iPhone Charging Speed with Different Power Adapters

Using a power adapter larger than the one designed for your iPhone can indeed speed up the charging process, but the extent to which this occurs depends on the capabilities of both your phone and the charging adapter.

The Science Behind iPhone Charging Speed

The rate at which an iPhone charges is governed by the interplay between the maximum output of the charging adapter and the charge rate programmed into the battery controller within the phone. At any given moment, the charge rate is always the lesser of two factors:

The maximum charge rate that the battery and charge controller can accept, given an ample power supply. The maximum power that the charging adapter can actually deliver.

Apple and compatible charging adapters communicate the maximum power they can provide through the two USB data lines in the charging cable. The charge controller in the phone ensures it never tries to draw more power than it can handle, thereby maintaining a safe and efficient charging process.

Older iPhone Models

For older iPhone models, such as those designed to charge at 1 A (5 W maximum), using a larger adapter like an iPad charger will not increase charging speed. The built-in charging controller will only utilize the available power, which matches the original design.

Newer iPhone Models

Starting from the iPhone 6 onwards, newer models have batteries and charge controllers that can handle higher current, potentially allowing for faster charging. For instance, my iPhone 7 can theoretically charge at up to 2 A. When charged from a 5 W cube adapter, the charge rate will be limited to 1 A. However, using an iPad charger or a compatible charger that can provide 2 A or more will result in a charge rate of between 1 A and 2 A for most of the charging period, cutting the time needed for a 80% charge in half.

Practical Charging Methods

While some may claim that certain portable battery packs or chargers can deliver higher currents, results can vary. For example, some portable battery packs, like those from PNY, can indeed charge at 2 A from their high-current outputs, but not all devices are capable of this. Some, like a TP-Link battery pack, might still supply only 1 A, due to different signal protocols used by the charging adapters.

Important Considerations

It's important to verify the actual charge rate of the charging adapter before using it. Utilizing a portable battery pack or a charging adapter that does not properly signal the charge controller of your iPhone can limit the maximum charge rate to 1 A, even if the adapter itself can supply 2 A.

Conclusion

To summarize, while larger power adapters can potentially lead to faster charging, the actual outcome depends on the compatibility and capabilities of both the charging adapter and the phone. Always ensure that your charging adapter is compatible with and capable of delivering the necessary power to maximize charging speed.