Wireless charging has its perks. You can place your phone on a pad, as long as it’s centered, and it starts charging without a cable. I lent one to a relative whose iPhone port broke and can no longer charge over a wire. It’s a handy solution to the dreaded moisture detection error on Android phones, too.

However, beyond the small conveniences, I don’t find my Samsung wireless charger to be a great primary charging device. It’s slow, highly inefficient, and the heating issue after months of use might have caused my Note 20 Ultra battery to gain a potbelly. I’m going to keep my current charger, but I’m unlikely to buy a new one anytime soon.

Wireless chargers are highly inefficient

They waste far more energy than a simple cable

With wired charging, power flows directly from the outlet through a cable into your phone. Even with a good GaN charger, you lose about 35% of energy along the way, but that’s still the most direct path available.

Wireless charging skips that direct connection entirely. Instead, the charging pad has a coil that generates an alternating magnetic field, and your phone has a matching coil that catches that field and converts it back into current. That whole process of generating a field to induce a current elsewhere is inherently wasteful. Energy bleeds off in the conversion itself, and it gets worse when the two coils are misaligned or spaced apart.

The numbers make the gap hard to ignore. Even in the best-case setup, using Apple’s MagSafe or the Qi2 standard with magnets forcing perfect coil alignment, wireless charging still burns 36% more energy than wired, according to iFixit’s testing. In their worst-case test, a phone sitting slightly off-center on a generic AmazonBasics pad consumed 104% more energy and took twice as long to charge. Tesla’s in-car wireless charger performed just as poorly, since its multiple coils are almost never properly aligned with the phone sitting on it.

The inefficiency isn’t a manufacturing defect in any one product. It’s baked into how induction charging works: generating and catching a magnetic field is simply a lossier way to move energy than sending it down a wire.

Wireless chargers can cook your battery

The wasted energy turns into heat, right against your battery

Since a chunk of that transferred energy doesn’t turn into actual charge, it has to go somewhere, and it goes straight into heat. That heat builds up in the coil sitting directly against your battery, which is the one component in your phone most sensitive to it.

iFixit’s tests showed that wired charging kept battery temperatures under 29°C the entire time. Every wireless setup they tested crossed the 30°C threshold, which is where battery degradation starts to accelerate. MagSafe and Qi2 chargers with magnetic alignment still pushed battery temps up to 35°C. A phone placed slightly off-center on a generic pad sent temperatures above 40°C and kept them there for extended periods.

When lithium-ion batteries are regularly exposed to that kind of heat, the electrolyte inside starts breaking down. Gas builds up inside the cell, and the battery physically swells. That swelling pushes outward against the phone’s enclosure, and the back panel, usually the weakest point, is what gives way first. That’s exactly what happened to my Note 20 Ultra. After months of sitting on a wireless charger overnight, the back glass popped loose. Samsung phones with glass backs are especially vulnerable here, since the adhesive holding them weakens further when subjected to repeated heat cycling.

If you game or do anything intensive on your phone while it charges, using bypass charging on your Android phone is a far better approach, since it powers the phone directly from the wall and skips the battery entirely during heavy use.

Only charges when placed properly in a position

Slight misalignment can double your charging time

Wireless charging efficiency hinges almost entirely on whether the pad’s coil and the phone’s coil are lined up. Any misalignment, even by a few millimeters, increases energy loss and heat.

MagSafe and Qi2 solve this with embedded magnets that snap the phone into the right position every time. But even with that near-perfect alignment, you’re still losing 36% more energy than wired and hitting 35°C. Without those magnets, on a flat pad where you just drop your phone, iFixit measured a 104% increase in energy consumption and double the charging time when the phone was placed slightly off-center.

Tesla’s charging platform is a cautionary example. It uses many transmitting coils spread across the pad instead of a single aligned pair, so no matter where you set the phone, it’s never centered on any one coil. The result mirrors the worst-case scenario: extended charge times, higher energy use, and sustained temperatures in the high 30s to above 40°C. A cable either connects or it doesn’t. There’s no equivalent failure mode where you plug in slightly wrong, and your charger suddenly becomes half as effective.

The cost doesn’t justify the feature

You’re paying more for less

Wireless chargers cost noticeably more than their wired counterparts for the same or lower wattage. Samsung’s own 15W wireless charging pad retails for around $35 to $60 depending on the model, and that’s for a single-device pad. The Wireless Charger Duo, which charges two devices at 15W, goes for $89.99 on Samsung’s website. Compare that to Samsung’s 25W wired wall charger with a USB-C cable included, which regularly sells for $10 to $25. You’re paying two to six times more for a charger that delivers slower speeds and wastes more energy doing it.

Third-party options can be a bit more affordable, but the gap persists. A Qi2-certified 15W magnetic wireless charger from brands like INIU or Anker runs about $10 to $33. A comparable 25W wired USB-C charger from the same brands costs $8 to $15. The wireless option still costs more and charges slower, and you’re still dealing with the heat and efficiency losses on top of that. So what are you really paying for? Skipping the act of plugging in a cable. That’s the entire value proposition, and it comes with a disproportionately higher cost.

Then there’s the hidden cost. The wasted energy from wireless charging turns into heat that gradually degrades your battery. That doesn’t show up at the register, but it shows up later as reduced capacity or a battery that needs replacing sooner. If you want to keep track of that wear, your Samsung phone has a hidden diagnostics menu that shows the real battery health beyond the generic “Normal” label. With USB-C now standard across almost everything, dealing with cables really just means plugging in, which takes a few seconds.

Wireless chargers can’t replace your primary charger

Wireless charging still has a place if you don’t need fast charging speeds or only use it occasionally. It’s handy in a car where a cable adds clutter and is a headache to manage. And it’s a viable fallback for when your USB port eventually gives up, which rarely happens but can save you an expensive repair on an older phone.

But in my case, I’ve stopped using it as my primary charger. The heating issue alone is enough to discourage me from using it for prolonged periods. I want my charger to give me a quick boost when the battery saver kicks in and the low charge warning pops up, not waste energy along the way. A good USB-C cable and a decent charger do that job faster, cooler, and cheaper. That’s a trade I’m happy to make.