A power supply (1) for a pulsed load (2) includes a first energy
storage device in the form of a battery (3) which is in parallel with a
second energy storage device in the form of a supercapacitor (4). Battery
(3) and supercapacitor (4) are respectively modelled as: an ideal
battery (7) in series with an internal resistance (8); and an ideal
capacitor (9) in series with an equivalent series resistance (ESR) (10).
Through use of a supercapacitor (4) having a low ESR with respect to the
resistance (8), the power supply (1) facilitates continuity of supply
to load (2). That is, during peak demand more of the load current will be
supplied by supercapacitor (4) due to the lower ESR. Moreover, during times
of lower load current demands the battery recharges the supercapacitor. This reduces
the peak current needed to be provided by the battery and thereby improves battery longevity.