If you want to cut the cord and move away from a mains power supply you need to get a gadget that is powered by batteries. Of course many devices are sold without lithium batteries, while others will come with cheap cells that will run out quickly, making it necessary to buy replacement batteries at regular intervals.
It is relatively easy to find lithium batteries and other bike batteries because in general devices will make use of cells that are compatible with a number of different products, whether they are related to cycling or not. Major brands like Duracell and Energizer produce bike batteries and replacement batteries so that you can repower your heart rate monitor, GPS device or headlight system with ease.
Of course battery-powered electric bikes are becoming more popular and batteries are unsurprisingly more important than ever if you decide to buy a cycle which uses more than just pedal power to push you forwards. Different electric bikes have different battery types, capacities and outputs so it is vital that you consult the instructions from your individual manufacturer to ensure that you buy the right replacement cell when the time comes.
When you buy rechargeable batteries for your bike you may want to consider what you will do if you are out in the countryside away from a power adapter and you run down the charge on your gadgets. Brands like BioLogic produce portable charging systems for just such an occasion, allowing you to recharge anything from a GPS unit to an iPhone. As long as the gadget has a USB connection then devices like this will be a boon.