An Ultracapacitor is a capacitor that has an unusually large amount of energy storage capability relative to its size when compared to common capacitors. These are of particular interest in automotive applications for hybrid vehicles and as supplemental storage for battery electric vehicles. Such energy storage has several advantantages relative to batteries: Various types of capacitors A capacitor is a device that stores energy in the electric field created between a pair of conductors on which equal but opposite electric charges have been placed. ... Honda Insight, a hybrid gas-electric vehicle 2004 Toyota Prius, a hybrid gas-electric vehicle A hybrid vehicle uses multiple energy sources or propulsion systems to provide motive power. ... Battery Electric Vehicles or BEVs are electric vehicles whose main energy storage is in the chemical energy of batteries. ... Four double-A (AA) batteries In science and technology, a battery is a device that stores energy and makes it available in an electrical form. ...

• Very high rates of charge and discharge.
• Little degradation over hundreds of thousands of cycles.
• Light weight
• Low toxicity of materials used.
• High cycle efficiency (95% or more)

Disadvantages:

• The amount of energy stored per unit weight is considerably lower than that of an electrochemical battery (3-5 W.h/kg for a UC compared 30-40 W.h/kg for a battery).
• The voltage varies with the energy stored. To effectively store and recover energy requires sophisticated electronic control and switching equipment.

The volt (symbol: V) is the SI derived unit of electric potential difference. ...

See also

Capacitor Various types of capacitors A capacitor is a device that stores energy in the electric field created between a pair of conductors on which equal but opposite electric charges have been placed. ...