Cut'n'paste:
Supercap 9VDC Battery
http://www.bairesrobotics.com.ar/ele...%20Battery.pdf
9V batteries are often found in devices that arent used very often. If you use a NiCd rechargeable battery you may find it completely discharged by the time you need it.
Capacitors on the other hand can maintain their charge for years. This circuit uses a 10F cap with a switching voltage regulator to increase the voltage from 2.3V to 9V.
With a light load the cap will last up to 3 hours and once discharged it can be recharged in less than 20 seconds. Warning: PDF link.
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I remember back in the 70s' asking one of my electronics teachers at DeVry why they couldn't make FARAD size capacitors as an alternate to battery power. He responded a FARAD is a tremendous amount of energy and just one farad would be a capacitor the size of his desk.
We know now that is NOT true and I don't fault him for the statement as they new have supercaps that go up to 2700 FARADS as at;
http://www.eeproductcenter.com/showA...leID=164300055
Maxwell's executive vice president for strategic business development, said that the just-released 2.7-volt BOOSTCAP MC2600 2,600-farad large cell and fully integrated BMOD2600-16 16-volt module, incorporating six MC2600 cells, establish new industry standards for performance and price.
Maxwell's executive vice president for strategic business development, said that the just-released 2.7-volt BOOSTCAP MC2600 2,600-farad large cell and fully integrated BMOD2600-16 16-volt module, incorporating six MC2600 cells, establish new industry standards for performance and price.
And at 10 cents per farad the cost was relatively high. "To those who ask if we can reduce cost, I say we must be at half a cent per farad by 2010," he said. The companys new MC2600, at a cost of 1 cent per farad in high numbers (1 million units annual volume) and with a production volume that is presently expected to approach 100,000, goes a long way towards meeting that goal.
In practice, units can be series-connected up to 1,000 volts (based on existing safety requirements, not the limitation of the supercap). Most practical applications extend to about 700 to 800 volts, according to the company. There is no balancing requirement for units connected in parallel.
BOOSTCAP ultracapacitors deliver up to 10 times the power and longevity of batteries, require no maintenance and operate reliably in extreme temperatures. In transportation applications, they efficiently recapture energy from braking for reuse in hybrid drive trains, reducing fuel consumption and emissions, and provide compact, lightweight, "life-of-the vehicle" solutions to stabilize automotive power networks and power new, all-electric subsystems, such as drive-by-wire steering.
In mission critical industrial applications, where backup power is critical for continued operation or a soft shutdown in the event of power interruptions, they provide reliable, cost-effective, maintenance-free energy storage.
In wind turbine blade pitch and braking systems and other industrial applications, they provide a simple, solid state, highly reliable, solution to buffer short-term mismatches between the power available and the power required.
Maxwell's silver hammer
