TTI’s supplier marketing manager, Pat Denton, reviews the development of supercapacitors and how they’re poised to change the ways electronics are designed.
While supercapacitors, or electric double layer capacitors (EDLCs), have been around for a while, they are just now gaining a wider acceptance. Reasons for this delayed acceptance include more suppliers, lower price and more packaging options. Also, suppliers have improved component specifications to include higher voltages and wider operating temperatures.
Supercaps, also called UltraCaps or GoldCaps, offer a much higher capacitance value. Think farads rather than pico or microfarad but with lower voltage limits.
Single cell supercaps range from 2.5 to 3V. Single cell packaging includes: cylindrical radial, 13mm button cell, larger snap-in and screw-terminal packages and surface-mount v-chip. Large-can, single cell supercapacitors are available in an unbelievable 4,000F.
Lighter and more capable
Supercaps developments bridge the gap between electrolytic capacitors and rechargeable batteries. New developments are pushing the crossover further, with single cell hybrid supercaps now available up to 3.8V. Manufacturers can put two or more cells in series to create supercapacitor modules offering 5V to over 200V.
Supercap modules can be as big as a truck battery or a full computer server rack, with almost 100 individual cells in each. Supercapacitors also deliver weight savings: while visiting a customer recently, I was pleasantly surprised at how little a module containing 16 large, snap-in supercaps weighed. Regarding temperature, many supercapacitors offer an operating temperature range of -40 to 85oC, far better than batteries.
Longer lifespan
Perhaps supercaps’ biggest advantage is they can be charged/discharged many more times than a battery. Where a battery may be rated for 500 to 1,000 charge cycles, a supercapacitor can deliver 20,000 charge/discharge cycles. Also, supercaps charge in seconds or minutes, versus hours for batteries.
Longer lifespan also delivers maintenance savings. Case in point, real-time clock back-up is the number one supercaps application. In many cases, the supercapacitor lasts over a decade, effectively the life of the product.
On a larger scale, manufacturers have made modules with the form factor of car and large truck batteries. These modules can start a truck, boat or generator, after which a lead-acid battery takes over. Supercaps extend lead-acid battery life and offer plenty of starting power, even in sub-zero temperatures.
Aiding electrification
In one final application example, there is an opportunity to install supercaps at bus stops. Power from those modules could assist with power-heavy tasks, such as opening and closing doors, further preserving the vehicle’s drive batteries. Meanwhile, thanks to the fast-charging capability, those capacitors will be recharged while the bus is driving to the next stop.
As electrification comes to other types of vehicles, more applications for auxiliary supercapacitors can be found. For example, garbage trucks could use supercap modules to run their compactor arms instead of revving their engines to generate the extra power.