Utilizing super capacitors to improve battery performance in electric mobile machinery

This project tested the impact of incorporating a super capacitor into a battery electric drivetrain for off-road machinery. The 188 F super capacitor was added to a 1250 Ah, 36 V nominal battery system of a three-wheel production forklift with a rated load capacity of 2268 kg. The forklift was operated according to the procedures outlined in Abnormal Operation Heat Rise Test per UL 583 with an 1800 kg load. The test was conducted twice with the super capacitor in operation and twice without. Current into the super capacitor and battery as well as system voltage were recorded. The super capacitor reduced maximum voltage spikes which were caused by regenerative braking from 42 V (22% over nominal) to 39 V or less (12% over nominal). Maximum regeneration currents into the battery were reduced from 590 A to 220 A. Total current into and out of the battery during each test run was reduced by 18% when the super capacitor was added, which would improve battery life. Vehicle power levels and responsiveness during the operation were not negatively impacted by the addition of the super capacitor. The addition of a super capacitor had a beneficial impact on the electrical system of the vehicle without altering the operator feel or its responsiveness.