Solar Power Challenge                                Author Kieron McGeever             Last update: 21/11/2007 21:11:21

Why Super Capacitors?

Facts about Super Capacitors

Capacitors store energy in an electrostatic field rather than as a chemical state as in batteries. Capacitors are probably the most common form of non-chemical energy storage and are widely used in low power applications. Super-capacitors are now widely available for school use. The most popular is the 10 Farad 2.5 Volt device pictured here.

Facts about batteries

At the moment in the world we throw away 15 billion ordinary batteries a year.  Primary batteries can contain highly toxic heavy metals such as cadmium and mercury that can and do cause pollution problems when sent to landfill sites.  Rechargeable batteries contain reversible chemicals and can have a re-charge of over 1,000 cycles, but they are expensive. Using rechargeable batteries helps reduce the number of batteries requiring disposal, but 80% of them still contain nickel cadmium, a known human carcinogen. The energy needed to manufacture a battery is on average 50 times greater than the energy it gives out.

Applications of Super Capacitors

Applications requiring a short duration power boost or long duration low drain are the best. Most small motors do have only relatively low current consumption so runs of 1-3 minutes are possible with careful motor selection.  High value capacitors have a lot to offer for powering electronic devices and small motors for short periods of time. They can also be charged from a solar panel, a power supply, a dynamo, or direct from a battery. Running two capacitors in parallel provides extended (double) duration and in series up to 5 Volts capacity.

The advantages of super capacitors include:

Cannot be overcharged  

Long cycle life of more than 500,000 cycles at 100% DOD  

No chemical actions

10 to 12 year life