Yes, your old 18W adapter charges the iPhone 12 as fast as the new 20W charger
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our iPhone 12 5W vs 18W vs 20W vs MagSafe charging speed test article, but there is now more proof that you don't need to be the person splurging for something you have at home.By not including a charger in the iPhone 12 series boxes, Apple stirred the beehive of charging questions around its new handsets. Luckily, we answered most of those in
Fastest iPhone 12 20w vs 18W vs 5W charger
- 101 vs 102 vs 199 minutes
One would think that the 20W, 30W or even 61W charger of Apple would be the one that delivers the fastest charging times, and they would be wrong, as the management of the whole charging circuitry, from the outlet, to the battery inside the phone, is what's in play here.
The charging algorithms start strong, then taper the current off after the phone is about three quarters in, then the charging speed trickles to a near halt towards the 100% in order to preserve the battery chemistry. Thus, even using Apple's most powerful chargers won't result in charging the iPhone 12 faster than the good ol' 18W brick in the iPhone 11 Pro series boxes.
Aukey, the maker of all things charging, compact and affordable, ran a test with all of Apple's most popular chargers, including the new 20W one, and found nearly identical speeds once you pass the 12W charger mark. It recorded the voltage and current, and the 18W, 20W, and even 65W Apple chargers, delivered speeds a bit above the 1 hour and 40 minutes mark, something we can also attest to.
As you can see, the charging curves of the three top chargers in the test are almost identical, so you can basically use them interchangeably. If you have an oldie 12W iPad adapter, that would work too, but prepare to wait quite a bit more, while the Apple's most widespread 5W charger will be a teaching experience in patience, as it takes more than 3 hours to top up the iPhone 12 and 12 Pro.
Bummer, but the silver lining is that if you have an 18W charger already, buying the new 20W brick makes little sense, even if it's less than last year's 18W unit. Getting Aukey's Omnia 20W charger, however, makes more sense, as not only is it cheaper than Apple's 20W piece, but is also much more compact to carry around or fit in the outlet among all of your other gadget's adapters.