40w fast charge is used with heat, this is because any electrical current flowing through the electrical appliance will use the electrical heating when doing work, so in the 40w fast charge when the current flowing through the 40W fast charge will also make the fast charge heat up and heat up, but if you touch the 40W fast charge feeling extremely hot or extremely hot, the fast charge should be removed from the socket immediately. To prevent the current is too large and burn the fast charge.