Lithium AA batteries are single-use primary cells, chemically distinct from rechargeable NiMH or common alkaline AAs, built specifically for reliability during long storage and demanding use. Their standout trait is shelf life: many lithium primary cells retain the bulk of their charge for a decade or more, with minimal self-discharge, so a pack bought today is still ready to go in a grab bag five or ten years later. They perform far better than alkalines in cold weather, an important trait for anyone storing torches or radios in an unheated shed, garage or vehicle over a UK winter. Because they slot directly into existing torches, head torches, radios, smoke alarms and other AA-powered kit, no charging infrastructure is needed at all: you simply swap the cell and the device works. Expect to pay roughly £1 to £2 per cell, or £10 to £20 for a multipack of eight.
A power bank is a rechargeable lithium-ion or lithium-polymer battery pack with USB output ports, designed to top up phones, tablets, USB torches and other USB-powered devices. Capacities for portable models commonly range from around 10,000mAh up to 20,000mAh or more, enough for several phone charges before the bank itself needs recharging from the mains, a car charger or a solar panel. Unlike lithium AA cells, a power bank is not a source of new energy; it is a reservoir that must be filled beforehand and eventually runs dry during an extended power cut unless you have a way to refill it. The two products are genuinely complementary rather than competing: one keeps AA-powered torches and radios running, the other keeps phones and USB devices alive. Budget for roughly £15 to £25 for a basic 10,000mAh bank, rising to £30 to £50 for larger or fast-charging models.
