Take a battery charging unit, and plug it into the wall. Connect the battery cable to the charger, ensuring that the following safety protocols are met:
The battery is within a specialised lithium polymer battery bag.
The charger is in a well ventilated space – NOT within the same bag as the battery.
The temperature of the room and inside the bag is at an average room temperature.
Do not charge with a broken cable.
Do not leave the charger unattended, and make sure neither the charger or the battery is on a flammable surface.
If a fire breaks out, it’s best not to try to reduce its effects through traditional methods (water). Lithium fires generally need to burn out themselves, as it’s difficult and unsafe to put them out yourself.