Sentence:  [The voltage of a single cell is] too low for most applications [... so] a series of cells will be used to obtain the desired voltage – a "<WSD>battery</WSD>" of cells, in the strictest sense of the term. 
Meaning of the word marked with <WSD> tags:  A device used to power electric devices, consisting of a set of electrically connected electrochemical or, archaically, electrostatic cells. A single such cell when used by itself.