Maxwell Technologies Shipping 3rd Generation K2 Series Large Cell BOOSTCAP Ultracapacitors
26 February 2010
| One of the K2 series ultracapacitors. |
Maxwell Technologies, Inc. introduced its new K2 Series large cell BOOSTCAP ultracapacitors. The K2 replaces Maxwell’s previous MC series cell, the most widely sold large cell ultracapacitor in the world with more than 1 million cells currently in service.
Primary applications for Maxwell’s K2 series products, which operate at 2.7 volts and range from 650 to 3,000 farads, include automotive subsystems; hybrid and electric vehicle drivetrains; renewable energy systems; back-up power; grid stabilization; electric rail system power; and many other transportation and industrial applications that require burst power and heavy cycling that cannot be efficiently provided by a battery or power supply alone.
The K2 Series can work with batteries for applications that require both a constant low power discharge for continual function and a pulse power for peak loads. In these applications, the device relieves batteries of peak power functions resulting in an extension of battery life and a reduction of overall battery size and cost.
The company is currently shipping K2 cells in production volumes and multi-cell modules ranging from 16- to 125-volts.
| Maxwell K2 Series Ultracapacitors | ||||||
|---|---|---|---|---|---|---|
| Specification | BCAP0650 | BCAP1200 | BCAP1500 | BCAP2000 | BCAP3000 | |
| Nominal capacitance | 650 F | 1,200 F | 1,500 F | 2,000 F | 3,000 F | |
| ESR, DC (max, room temp.) |
0.8 mΩ | 0.58 mΩ | 0.47 mΩ | 0.35 mΩ | 0.29 mΩ | |
| ESR, 1 khz (max) | 0.6 mΩ | 0.44 mΩ | 0.35 mΩ | 0.26 mΩ | 0.24 mΩ | |
| Pd | 6,800 W/kg | 5,800 W/kg | 6,600 W/kg | 6,900 W/kg | 5,900 W/kg | |
| Pmax | 18,900 W/kg | 15,900 W/kg | 18,500 W/kg | 19,400 W/kg | 14,800 W/kg | |
| Emax | 4.11 Wh/kg | 4.67 Wh/kg | 5.42 Wh/kg | 5.63 Wh/kg | 5.96 Wh/kg | |
| Max continuous current | 62 A | 81 A | 97 A | 123 A | 147 A | |
| Max peak current, 1 sec. | 575 A | 955 A | 1,185 A | 1,585 A | 2,165 A | |
| Leakage current | 1.5 mA | 2.7 mA | 3.0 mA | 4.2 mA | 5.2 mA | |
The K2 cell design features a rugged welded electrical pathway with increased contact and higher surface area. Maxwell says that features and benefits of the K2 series ultracapacitor cells include:
- Ultra-low internal resistance
- Highest power performance now available
- Lowest resistor-capacitor (RC) time constant
- 2.7 V operating voltage
- Over one-million charge/discharge cycle lifetime
- Superior performance at extreme temperatures
- Proprietary material science and packaging technology
Maxwell manufactures and markets additional BOOSTCAP ultracapacitor products ranging from 10 to 350 farads and multi-cell modules based on those products for wind turbines, smart utility meters and a variety of other industrial, telecommunications, information technology and other applications.
These new cells have improved the power density by 50% over the MC cells from 2005. However, the energy density stays the same. Compared to upcoming ultra high power lithium batteries Maxwell’s capacitators will still be superior in terms of their extremely good cycle life and their ability to charge at freezing temperatures. It would be nice though to see some improvement on energy density and price.
Previous cells
Posted by: Account Deleted | 26 February 2010 at 03:00 AM
Am I reading this right? 5.96 Wh/kg means you would need 215 kg of these to carry the same energy as a Prius battery?
That could be useful in a saw-tooth-pattern series hybrid. The Genset kicks on at 30% efficiency, charges the Supercaps with perhaps 60 to 90 seconds of juice, then shuts off until the charge falls below a certain threshold again. The genset probably turns on and off 30+ times per hour, and the supercaps probably cycle at least once every two miles the vehicle is driven, but the supercaps can handle 10x that many cycles lifetime, so no problem.
What is the price? How much would it cost to have enough of these to power a 1200 Kg vehicle for 60-90 seconds?
Posted by: HealthyBreeze | 26 February 2010 at 09:50 AM
"5.96 Wh/kg"
They are not made to replace batteries but to act as a buffer to prolong the life of the batteries or be used as storage for something small like a BAS. They can provide plenty of amps for take off and absorb regenerative braking energy like a sponge.
In a BAS configuration they would absorb regenerative braking energy and supply that on take off from a stop. The rest of the energy would be make up by the alternator charging further after take off.
City mileage would go up. However, they are 2.7 volts so you would need almost 100 of them to get up to 240 volts, another good reason to use them in a 48 volt BAS.
Posted by: SJC | 26 February 2010 at 12:21 PM
Many battery technologies dont resist multiple quick charges and discharges. Adding super-caps to handle what batteries dont do very well whould:
1) extend batteries life.
2) allow better accellerations
3) increase braking energy recuperation.
Would be above advantages be enough to offset the extra cost and weight?
Will future enhanced batteries require the assistance that super-caps provide?
Posted by: HarveyD | 26 February 2010 at 02:11 PM
If these cost $20 each (a guess) and you need a 100 of them that would add $2000 at least to the cost to make the car. An extra 1 kWh of batteries might cost less and allow a more aggressive use of the electric motor for longer periods.
Posted by: SJC | 26 February 2010 at 05:15 PM