This paper evaluates the changes in the ripple current for an electrolytic capacitor used in the dc-side of a single-phase rectifier circuit when subjected to input voltage fluctuations. The study has been undertaken in order to analyse the potential impact on capacitor lifetime. The key effect is that the capacitor ripple current, as a consequence of voltage fluctuations, increases dramatically and this phenomenon keeps deteriorating as the frequency of the voltage fluctuations increases. Simulations and experimental work confirm this phenomenon. Since the power loss and temperature rise are dependent on the capacitor equivalent series resistance (ESR) and ripple current components, an increase in ripple current under voltage fluctuation conditions is likely to accelerate this process, resulting in a reduced lifetime.