That an AC adapter or battery charger continues to use electricity even when it is not plugged into the device? Recently, manufacturers have reported that most adapters or chargers continue to consume as much as 40% of the electricity that it normally does during usage or charging of the device... such as mobile phones, power tool chargers, laptop computers and the like.
In these times of increasing energy costs, higher prices of everything, we need to minimize use of things, right? Unplug that alarm clock in the guest room! Unplug the phone charger when its not in use, your laptop charger? unplug it if its not being used!
You may notice that when these chargers are plugged into a wall outlet, they're a little warm even though they are not plugged into the device they are designed to power up or charge. This heat can only be created by the consumption of electricity. The transformer in these adapters continue to draw electricity and produce the heat at anytime it is plugged into an electrical outlet.
So, unplug all of your unused chargers and adapter when not in use... you will save some electricity, and although it may not be noticeable on your electric bill, it may be saving you a couple of bucks per month.