Four fire engines and around 25 firefighters attended a fire at a hotel on Leinster Square in Bayswater.
Part of a room on the first floor of the five-storey hotel was damaged by fire. Two adults were treated on scene by London Ambulance Service for smoke inhalation.
The fire is being treated as accidental and believed to have been caused by the failure of a lithium-ion battery in a power bank.
Lithium batteries store a significant amount of energy in a very small space and are much more powerful compared to other types of batteries. If that energy is released in an uncontrolled way, then a fire or explosion may result. If there is overheating, crushing, penetrating or overcharging, then a fault can occur within damaged battery cells which may cause the battery to catch fire.
A London Fire Brigade spokesperson said: “Lithium batteries are susceptible to failure if incorrect chargers are used, so it’s important to always use the correct charger for the product and buy an official one from a reputable seller.
"You should unplug your charger when you have finished using it and we would advise not to leave it unattended or charging while people are asleep.
“Batteries can present a fire risk if they’re over-charged, short circuited, submerged in water or damaged, so it’s really important to protect them against being damaged too.
“Try to ensure they are not getting knocked around while in use or while being carried as this can increase the chance of damage to cells."
The Brigade was called at 0253 and Control Officers mobilised crews from Paddington, North Kensington and Kensington fire stations to the scene. The fire was extinguished by 0354.