Four fire engines and around 25 firefighters tackled a fire involving several outbuildings on Sutherland Avenue in Orpington.
A garden shed and a tree were destroyed by fire and most of an outbuilding and another shed were damaged. There were no reports of any injuries.
The fire is believed to have been accidental and caused by the failure of a lithium battery in a power tool.
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’s Control Officers took the first of five calls to the fire at 1405 and sent crews from Orpington and Sidcup fire stations to the scene. The fire was under control by 1534.