Since two-way radios are mobile devices, obviously they operate on battery power. The batteries used in most of the models are rechargeable type, with some of the devices working on AA or AAA type non-rechargeable, throwaway batteries.
It is, therefore, important to make the batteries last as long as possible. The rechargeable batteries used in two-way radios are generally of Nickel Cadmium (NiCd), Nickel Metal Hydride (NiMH), lithium ion (Li-ion) or lithium ion polymer (Li-ion polymer). NiCd batteries suffer from the "memory effect", which has been eliminated with the use of lithium ion (Li-ion) batteries. Li-ion batteries also have twice the energy of NiMH batteries and they weigh 33% less.
The battery saver feature of the two-way radio, also called low power mode or the sleep mode. It helps in extending the life of the batteries in use. During usage, if the user has left the radio unused for a certain period of time, the feature switches the device to low-power mode to conserve power. The radio automatically switches to battery saver mode if there are no transmissions from it for more than 10 seconds. This time is adjustable in certain models of the two-way radio. This mode lets the clock run with display turned off so as to save the battery of the radio.