Qi2 explained: what the magnets actually changed

Qi has been the wireless charging standard on essentially every phone for years. Qi2, introduced by the Wireless Power Consortium, is the update, and its headline change is not a wattage number. It is magnets.

The problem Qi2 was designed to solve

Inductive charging works by lining up a coil in the pad with a coil in the phone. When they overlap well, most of the energy transfers. When they do not, efficiency falls off quickly and the energy that fails to transfer becomes heat instead.

On a flat, featureless pad, the user is responsible for that alignment, in the dark, one-handed, while half asleep. People are bad at it. The classic wireless charging complaint - I left it on all night and it was at 60 percent - is very often a phone that was sitting a couple of centimetres off centre.

What the magnetic profile does

Qi2's Magnetic Power Profile puts a ring of magnets around the charging coil in both the pad and the phone. Put the phone anywhere near the pad and it snaps into perfect alignment on its own.

Two things follow. Charging is consistently at full rate rather than sometimes at full rate. And because misalignment was the main source of waste heat, a well-aligned connection runs cooler, which in turn means the phone throttles less. The magnets fixed a user-experience problem and a thermal problem with the same component.

The secondary benefit is accessories: a magnetic ring is also a mounting system, which is why magnetic wallets, stands and car mounts all appeared at once.

Does Qi2 make your existing pad obsolete?

No. Qi2 is backwards compatible. A Qi2 phone charges on a standard Qi pad, and a standard Qi phone charges on a Qi2 pad - in both cases at the older, non-magnetic speeds and with alignment back in your hands.

Which matters more than the spec sheet suggests. A well-made standard Qi pad with a grippy surface, in a position where the phone naturally lands in the same spot every time, delivers a perfectly good experience. The magnets buy you tolerance for imprecision, not a different category of charging.

Magnets and your cards

The obvious worry, once you attach a magnetic wallet to a phone, is whether the magnets damage bank cards. For modern chip and contactless cards the answer is essentially no - the chip and the RFID antenna are not magnetic media. Older magnetic stripes are more vulnerable, though even there the strength involved is usually well below what causes problems. The full picture is in can magnets damage your credit cards.

What magnets can do is interfere with the charge itself if a card ends up between the phone and the pad - covered in charging through a case, card or wallet.

What to actually buy

If your phone supports magnetic alignment and you want a bedside pad you can hit without looking, the magnetic version earns its price. If your pad lives on a desk where the phone lands in the same place every time, a straightforward Qi pad with a decent power adapter does the same job for less.

Either way, the adapter matters more than the badge on the box. That, and the other six reasons wireless charging underperforms, are in why is my phone charging slowly.