Four fire engines and around 25 firefighters tackled a fire at a mid terraced house on Freelands Avenue in Croydon.
Most of the first floor was damaged by the fire. One woman was taken to hospital by London Ambulance Service.
The fire is believed to have been accidental and was caused by the failure of a lithium ion battery in a power bank.
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.”
Control Officers took the first of 13 calls at 1459 and mobilised crews from Croydon, Purley, Woodside and Wallington fire stations to the scene. The fire was extinguished by 1543.