Here's how you can add wireless charging to your old iPhone, quickly, easily, and for the fraction of the price of buying a new iPhone.
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Fitting the charging coil is easy. Just pop the wireless charging card into your iPhone's connector, fold it over the back, and pop it into a case and you're done.
You do lose the port on your phone (unless you're willing to disconnect the card) but if all you use it for is charging, then this won't matter much.
With a compatible in-car charger (such as this one) you can continue to charge your iPhone when on the move.
In my experience, these wireless charging systems work very well, and are far more convenient than having to plug a cable into the handset every time. The only time it isn't is when you want to use your iPhone while it's charging, then a cable is easier.
See also:
iPhone X wireless charging accessory not ready for launch: Analyst