Since the iPhone 4 has a completely different shape than the iPhone 3G/3GS, all those older cases don’t fit the new device. Unfortunately, this also includes external battery cases like the Mophie ...

However, the iPhone 16 Plus will have a 4,006mAh battery, down from the 4,407mah of the iPhone 15 Plus. Apple doesn't definitively list the mAh capacity of its batteries when it comes to the iPhone.

There is no harm to your iPhone by doing this, but simply put, you will be waiting significantly longer for your phone to reach 100%. With a 5-watt charger, it can take an iPhone 16 up to 4 hours ...