Why does charging slow down after 80%?
Lithium batteries use a two-phase charging process: Constant Current (CC) until ~80%, then Constant Voltage (CV) which gradually reduces current. This 'trickle charging' after 80% prevents overheating and extends battery lifespan significantly.
Can a higher wattage charger damage my device?
No. Your device only draws the power it needs. A 100W charger on an iPhone won't charge faster than a 27W charger—the iPhone limits intake. However, using a charger below your device's maximum means slower charging.
What's the difference between watts, volts, and amps?
Watts = Volts × Amps
Watts measure total power. USB-C can deliver 5V, 9V, 15V, or 20V at varying amps. A 20W charger might be 5V/4A or 9V/2.2A. Higher voltage = faster charging for devices that support it (USB-PD).
Should I charge to 100% every time?
For maximum battery longevity, no. Keeping between 20-80% is ideal. Modern devices have features like 'Optimized Battery Charging' (Apple) or 'Adaptive Charging' (Android) that learn your routine and delay charging past 80% until you need it.
Does wireless charging damage batteries?
Wireless charging generates more heat than wired, and heat degrades batteries faster. For occasional use, it's fine. For daily overnight charging, the impact is minimal since the phone spends most time at 100% anyway. Fast wireless charging produces more heat than slow.
Why is my phone charging slower than expected?
Common causes: using a non-compatible cable (USB-A to USB-C limits to ~12W), charging while using the phone (power goes to use, not battery), high ambient temperature (phone throttles to prevent overheating), or battery wear reducing charge acceptance.