(1)   Lithium batteries should always be charged with great care.  Battery charging should always be timed and never done overnight.  Bicycle should be stored inside with batteries and installed in a room with a smoke detector.  If stored outside in sunlight convection from the sunlight can reduce battery charging cycles and even result in fire.  While storing outside in the cold could prolong the life cycle it could still enhance internal corrosion of the batteries.  There are many other reasons to store your bicycle indoors in a safe environment, but I don?t have the time to explain to every small detail and chemistry.
(2)   Electrical wall outlet with surge protector minimum ? don?t use 2 prong ungrounded outlets. If you are using an extension with multiple outlets, make sure it has a working surge protection.  Remember this charger is 2 amps and can cause fires and or death.  Plugging and unplugging into the same outlet over time can cause surging ergo use outlets with surge protection.
(3)   Best to plug the female connector into the battery 1st (this will protect your controller) then put charging plug into desired surge protected outlet.  I use an extension with a surge protected outlet that I can turn on and off.  When I am done charging, I leave plug in the extension unit and turn the outlet off.  I remove the female connection from the battery.  When I charge again the plug extension plug socket is off and I can plug in the female directly to the battery 1st then turn on the plug extension socket to recharge the battery.  Thus no continuous plugging of the charger to a wall outlet.
(4)   Don?t run the battery lower than 10%, don?t store the bicycle & battery inside lower than 25%.  For best results store the battery between 60% and 75%. Don?t charge the battery to 100% unless you need to for additional range and then only when you intend to use the battery immediately after charging.
(5)   Its best to charge your battery just before using ebike.  Don?t charge battery more than 90%.