I switched to a wireless charging pad on my desk expecting the same result as a cable, just without the plugging in. Three months later my phone was noticeably warmer after an hour on that pad than it ever was plugged in directly, and it was also nowhere near full in the time a cable would have taken. Neither of those turned out to be a defect. Both are just how wireless charging actually works.
The Efficiency Gap Is Real, Not a Bad Unit
Wireless charging works by induction, sending power across a small air gap between two coils rather than through a direct wired connection, and that gap costs energy. Typical wireless setups run at roughly 60 to 70 percent efficiency, compared to 85 to 95 percent for a cable. The energy that doesn't make it into the battery becomes heat, which is why a phone sitting on a pad for a while runs warmer than one charging on a wire.
Why Wireless Is Also Slower, Not Just Warmer
Wired charging is typically two to four times faster than wireless. A phone on a decent wired charger can go from empty to full in around 25 to 40 minutes; the same phone on a 10-15W wireless pad often takes 60 to 120 minutes for the same result. Even newer Qi2 pads at 25W, which narrow the gap considerably, still land behind a basic wired charger of similar wattage.
What This Means for Battery Health Over Time
Heat is the main thing that degrades a lithium-ion battery's long-term capacity, more than charge cycles alone. Relying on wireless charging exclusively tends to cost a phone a few extra percentage points of battery capacity over a couple of years compared to charging mostly by cable, a small but real difference that compounds the longer a phone stays in daily use.
The Honest Verdict
A wireless pad is worth having for the moments convenience actually matters: overnight on a nightstand, or parked at a desk during a long work session where speed isn't the point. For anything time-sensitive, a low battery before heading out, a quick top-up between calls, a cable is still faster and runs cooler, and that gap isn't closing anytime soon. Keep both within reach and use whichever one the moment actually calls for, rather than picking one and assuming it covers every situation equally well.
