It is usually safe to leave a good charger plugged in without a phone, but it still uses small standby power and can become risky if it is damaged, counterfeit, hot, loose, wet, or poorly certified. Unplug questionable chargers and inspect warm outlets.

A power bank may stop charging a laptop because the wattage is too low, USB-C Power Delivery negotiation fails, the cable is not rated correctly, the laptop requests more power, the power bank overheats, or its low-current protection shuts down.

A charger may buzz because internal components vibrate under electrical load. A faint sound can be normal, but loud buzzing, heat, smell, flickering charging, or a damaged adapter means you should stop using it and check the charger.

A charger may spark when plugged in because electricity jumps briefly as the plug contacts the outlet. A tiny single spark can be normal, but repeated sparks, burning smell, heat, loose outlets, or damaged plugs need immediate attention.

Yes, a phone charger can catch fire if it is poorly designed, counterfeit, overloaded, damaged, overheated, or used with a bad cable or outlet. Stop using any charger that smells burnt, sparks, buzzes, melts, becomes extremely hot, or leaves scorch marks.