My dentist has a wall chart that admonishes, "You don't have to floss all your teeth, just the ones you want to keep."
The same logic goes for recharging equipment. So double up on everything.
Sound redundant? Not if the only recharger you packed for your camera is snapped off by the maid's vacuum cleaner. Or the wall adapter and its recharging cord are left in that hidden plug behind the headboard. Your camera is now a paperweight. So you don't have to bring recharging backup for all your equipment - "just the ones you want to function throughout your entire trip."
01. Country-Specific Plug Adapters
There are two kinds: A single plug adapter or a single device with multiple adapters.
Not sure which? This site can help: Plug & Socket Types.
Check this site for examples of Worldwide All in One Universal Travel Adaptors.
02. Two AA and Two AAA Batteries - You may never need these, but you will be a hero to any fellow traveler who's far from a Wal-Mart and desperate for her point and shoot camera or alarm clock to work again.
03. Two Batteries for Each Camera - They do quit without warning. And take more if you're going to be shooting in very cold weather. They drain quickly in the cold.
04. Two Rechargers for each Camera
05. Two Charge Cords for each Device - Your smartphone and tablet take the same cord? Have a cord for each. You can recharge both at the same time and there's backup if one is lost.
06. Gear Ties - Lots of twisted, tangled cords? These 3 inch Nite Ize Gear Ties are very helpful in shortening cords to needed lengths and keeping them from becoming an electrical string ball as we travel.
07. Multi-recharger Device - In some hotels, there may only be only one or two electrical outlets in the room and the first one could be behind the 300-pound headboard. Consider that and take an adapter that can handle recharging more than one device at a time such as this multi USB recharger.
And don't forget - newer TVs have USB ports on the side or back that can recharge your devices.
We store and carry all the electrical stuff in this handy Travel Gear Organizer