Four fire engines and around 25 firefighters were called to a fire at a house on Abbotts Road in Mitcham.
A single-storey garage was destroyed by the blaze and part of a end of terrace house was damaged. Part of a neighbouring maisonette was also damaged. There were no reports of any injuries.
Firefighters cooled and removed a propane cylinder which was involved in the fire as some cylinders can explode when exposed to heat.
The fire is believed to have been accidental and caused by the failure of a lithium-ion battery.
A London Fire Brigade spokesperson said: “Lithium-ion 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.
“Batteries can also pose a risk if they have been damaged, so try to ensure they are not getting knocked around while in use as this can increase the chance of damage to cells. You should also not expose them to extremes of temperature.
“You should always make sure you unplug your charger once it’s finished charging. Always follow manufacturers’ instructions when charging and we would advise not to leave it unattended or while people are asleep.”
The Brigade's 999 Control Officers took 19 calls to the blaze.
The Brigade was called at 2353 and the fire was under control by 0130 (on Saturday). Fire crews from Mitcham, West Norwood, Wimbledon and Croydon fire stations were at the scene.