Browse Definitions :
Definition

ultracapacitor

An ultracapacitor, also called a supercapacitor, is an electrical component capable of holding hundreds of times more electrical charge quantity than a standard capacitor. This characteristic makes ultracapacitors useful in devices that require relatively little current and low voltage. In some situations, an ultracapacitor can take the place of a rechargeable low-voltage electrochemical battery.

An excellent example of the use of an ultracapacitor can be found in so-called electrical smart meters. These devices, unlike their electromechanical counterparts, store information about home and business electrical power and energy consumption, and contain no moving parts. In the event of a power failure, an ultracapacitor allows the meter to send a final status communication to the utility company, preventing data loss and the confusion that could result. While a rechargeable backup battery can serve the same purpose, most electrochemical batteries fail at extremely low temperatures, such as commonly occur in the winter in much of the United States and virtually all of Canada. Ultracapacitors keep working at temperatures far below freezing.

Ultracapacitors can be found in emergency radios and flashlights. The ultracapacitor charges up with the help of a miniature direct-current (DC) generator that the user can manually operate for a couple of minutes by turning a small crank. Once the ultracapacitor has acquired a full charge, the device can function for quite awhile (in some cases over an hour) before it needs a recharge.

A conventional capacitor contains two electrically conductive surfaces, separated by an insulating layer called a dielectric. In general, the capacitance increases as the surface area of the conductors increases. The capacitance also goes up as the spacing between the surfaces decreases, and as the dielectric constant of the intervening insulator increases. However, a practical limit exists as to the capacitance obtainable with this design. An ultracapacitor differs fundamentally in its internal structure. Instead of having two electrodes separated by an insulating layer, an ultracapacitor employs a porous medium that produces the effect of a pair of plates with gigantic surface area, separated by only a few nanometers. As a result, the ultracapacitor has far more capacitance than any conventional high-capacitance component (such as an electrolytic or tantalum capacitor).

The principal disadvantage of the ultracapacitor, compared with older capacitor designs, is the fact that the ultracapacitor cannot withstand high voltage. While an electrolytic capacitor might be rated at several hundred DC volts, ultracapacitors have maximum ratings of only about 5 DC volts. In order to use ultracapacitors at higher voltages, multiple components must be connected in series (end-to-end, like the links in a chain). Then their voltage ratings add up, just as battery voltages add in a series connection. However, when multiple capacitors of any type are connected in series, special precautions are essential in order to equalize the voltages across the individual components. Otherwise, one of them might "hog" more than its share of the voltage and burn out as a result.

 

Continue reading about ultracapacitors:

Gigacom discusses the theory, advantages, and limitations of ultracapacitors.

Technology Review looks at emerging ultracapacitor technologies.

Ultracapacitors may someday allow wind farms to supply energy even when the wind fails to blow.

This was last updated in March 2012

Join the conversation

1 comment

Send me notifications when other members comment.

Please create a username to comment.

Hi,
I am currently working on a project where I am using the battery and super(ultra)capacitors as a hybrid energy storage system for a PV inverter system. I just need help in coming up with the rating of the supercapacitor that I would use? I know that I'm gonna have to connect many in series in order to attain the voltage of ~120V but what about the C ?
Thank you so much for your time.
Cancel

-ADS BY GOOGLE

File Extensions and File Formats

SearchCompliance

  • compliance framework

    A compliance framework is a structured set of guidelines that details an organization's processes for maintaining accordance with...

  • regulatory compliance

    Regulatory compliance is an organization's adherence to laws, regulations, guidelines and specifications relevant to its business...

  • privacy compliance

    Privacy compliance is a company's accordance with established personal information protection guidelines, specifications or ...

SearchSecurity

SearchHealthIT

  • telemedicine (telehealth)

    Telemedicine is the remote delivery of healthcare services, such as health assessments or consultations, over the ...

  • Project Nightingale

    Project Nightingale is a controversial partnership between Google and Ascension, the second largest health system in the United ...

  • medical practice management (MPM) software

    Medical practice management (MPM) software is a collection of computerized services used by healthcare professionals and ...

SearchDisasterRecovery

  • crisis management plan (CMP)

    A crisis management plan (CMP) outlines how to respond to a critical situation that would negatively affect an organization's ...

  • disaster recovery (DR) test

    A disaster recovery test (DR test) is the examination of each step in a disaster recovery plan as outlined in an organization's ...

  • business continuity plan (BCP)

    A business continuity plan (BCP) is a document that consists of the critical information an organization needs to continue ...

SearchStorage

  • kilobyte (KB or Kbyte)

    A kilobyte (KB or Kbyte) is a unit of measurement for computer memory or data storage used by mathematics and computer science ...

  • megabytes per second (MBps)

    Megabytes per second (MBps) is a unit of measurement for data transfer speed to and from a computer storage device.

  • zettabyte

    A zettabyte is a unit of measurement used by technology professionals and the general public to describe a computer or other ...

Close