It has been demonstrated experimentally that a capacitor bank when connected in parallel with a battery increases the energy output by mitigating the effects of high current spikes in the load. High current draws are taken from the capacitor bank which can furnish a small amount of energy quickly. The battery which can furnish substantial energy over a period of time then recharges the capacitor bank during times of decreased load. With a current square wave (P–P of 1.5 to 2× the average), capacitors afforded an increase in the retrievable energy of approximately 8% for a lead acid battery, 40% for a rechargeable lithium ion battery, and 46% for a non-rechargeable lithium ion battery.