by Jon Gabay,
Low-power microcontrollers have done much to improve longevity in energy-harvesting systems. Clever architectures and use of low-power modes lets micros draw nanoamperes of current while preserving registers and configuration data. This allows designers to use smaller and less dense energy storage solutions that were not feasible in the past. Nevertheless, energy storage, which plays a key role in ambient-energy-harvesting systems, is still needed in most cases as a power buffer to store enough energy to provide the power bursts needed to acquire and transmit data during peak demand, particularly if data is going to be transmitted across a wireless network. These energy storage devices generally take the form of either a battery or a supercapacitor (supercap).
Supercapacitor Options for Energy-Harvesting Systems - [Link]
The LT3763 is a synchronous buck LED driver controller that delivers over 300W of LED power. Its 6V to 60V input voltage range makes it ideal for a wide variety of applications, including automotive, industrial and architectural lighting. Similarly, its output voltage can be set from 0V to 55V, enabling it to drive a wide range of LEDs in a single string. The LT3763 offers both input and output current monitors and limiting, which accurately control both input and output current. The LT3763 also offers accurate output voltage regulation as well as input regulation, useful for high impedance sources such as solar panels. Its constant current and constant voltage regulation makes it ideal for applications ranging from driving high brightness LEDs to battery and supercap charging
LT3763 – 60V High Current Step-Down LED Driver Controller - [Link]
Double layer electrolytic capacitors already enable to replace backup batteries in many applications.
Modern high-capacity double layer capacitors (also known as supercapacitors) feature a very high energy/volume ratio, compared to usual electrolytic capacitors. Their capacity is so high, that they are able to replace backup batteries in many designs. On the market there are available miniature types as well as physically big types with capacities of tens to hundreds of Farads.
One of the biggest advantages of capacitors in comparison to batteries is their long lifetime, because their electrodes don´t undergo degradation neither after many thousands of cycles. On the other side, even modern batteries have a limited lifetime and a limited number of cycles, because energy storage in batteries is related to chemical changes of electrodes during charge/discharge (change from a solid to a liquid form, crystallization,…), what causes degradation of electrodes.
In our offer, you can find small “coin-type” double layer capacitors suitable for backup power supply of memories. For example a capacitor with a 1F (1000mF=1 000 000 uF) capacity charged at 5V can store energy of 12.5 Jouls (E=1/2*C*U2), what is 12.5 Wattseconds. This energy is in most cases sufficient to ensure a safe backup of memories at a voltage dropout. Such energy is also sufficient for a short time power supply of low power devices. This can be very useful for example for a safe write of data to EEPROM and a safe switch off of a device.
Supercapacitors instead of batteries? - [Link]
Here is an interesting project which uses capacitors to store energy instead of chemical,sit uses an different type of capacitors called Goldcap capacitors,GoldCap capacitors offer an interesting alternative power source when compared to conventional disposable or even rechargeable batteries. They can be charged very rapidly and can also deliver a high peak output current. Their voltage rating however is quite low so a little electronic assistance is necessary to raise the output voltage to a more useful level.PP3 (6F22) type 9 V batteries are often used in small portable equipment that require very little current and may only be used intermittently. Under these conditions its often the case that the battery is flat just when you urgently need to use the equipment. NiCd rechargeable cells are not a good choice in these applications because their self-discharge characteristics are much worse than dry cells and often there is no charge left after a long time in storage.
Superfast Rechargable Battery - [Link]