Choosing an Energy Storage Solution: How to Guarantee Critical Starts

by | Oct 16, 2012

As winter and freezing temperatures approach all too quickly, fleet managers have one nagging concern: will their vehicles start as the temperatures drop? School bus drivers and delivery truck drivers all hop into their vehicles and expect to start their engines and drive away within seconds to keep on schedule. But when you consider the many drivers of ambulances or fire trucks that need their vehicles to start right away in order to respond to emergencies, the situation becomes a bit more dire. While these drivers don’t choose the energy storage solutions within their vehicles, manufacturers, engineers and designers are all searching for the best solution for starting systems. They can find it with ultracapacitors.

A hybrid solution

Diesel engines tend to have higher engine friction levels, which means these types of engines are more difficult to start in cold temperatures. If a lead-acid battery is employed for engine cranking, the internal resistance will increase under cold temperatures. However, ultracapacitors solve this problem and can be implemented into vehicles with diesel engine starting needs: mining trucks, heavy equipment, locomotive starting systems, emergency vehicles or others. The cells operate with high efficiency, high charge acceptance and cycle stability in temperatures widely ranging from +65° Celsius to -40° Celsius. In contrast, batteries don’t operate well below 0° Celsius.

When combined with batteries, ultracapacitors help to reduce the load on the power source, and the two energy storage devices work together to achieve the optimal performance for each. The battery-ultracapacitor combination increases energy and improves the power density of the hybrid supply. This allows the battery to operate without its typical current spikes, giving it a longer and more effective life. The hybrid energy storage solution reduces the cycling of the battery under heavy load conditions so the hybrid supply can operate for longer periods of time and provide a more efficient energy supply.

The ultracapacitor module is capable of frequently starting the engine – even hundreds of times – and at lower temperatures than batteries can withstand. Achieving cold starts is certainly top of mind for design engineers, but it is important to note that ultracapacitors provide the necessary power for all critical starting applications, regardless of weather conditions. By providing critical start support, ultracapacitors significantly increase the reliability of the vehicle’s operation. Ultracapacitors are used for internal combustion engine cranking because they provide a quick and sound start. Employing such energy storage

technology in these kinds of starting system applications means engineers can guarantee that the engine will start without depending on the state of charge of the on-board battery.

Ultracapacitors provide additional economic benefits because they prolong the service life of the diesel starting system. The long lifecycle makes for little to no required maintenance, ultimately resulting in cost savings. Ultracapacitors reduce on-board battery maintenance expenses and fuel consumption, which increases the engine’s shelf life, and saves the fleet manager time and money.

Ultracapacitors power several automotive applications

With easier integration, higher durability and more power, ultracaps are quickly making their way into other automotive applications. They allow for a smaller battery pack, which saves space and reduces the overall weight of a vehicle. This contributes to substantial fuel savings.

In micro hybrid vehicles, ultracapacitors provide the power for the start/stop technology. Because ultracaps can handle large, dynamic and repetitive loads, they are an ideal technology for starting power, acceleration and regenerative absorption. No other energy storage technology can compete in these areas, as ultracapacitors are the sole technology capable of providing the power and cycle life necessary to provide the quick start that re-launches a vehicle. Engineers will adopt ultracapacitor technology for these applications at higher rates as new legislation restricting the amount of time drivers can idle their vehicles is adopted. Drivers are normally used to idling, for example at weigh stations, but changing these driving patterns will also change the type of batteries designed into vehicles.

Ultracapacitors are being designed into vehicles to provide backup power for brakes, steering and functions if batteries should fail. This emergency backup power extends to the power door locks or windows and also in-vehicle safety and communications devices such as GPS, signal horns, optical warning units, and airbag and security power.

Not limited to just one use in automotive applications, ultracapacitors are catching the attention of more design engineers and manufacturers who want to increase vehicle efficiency and reliability. Ultracapacitors are even more appealing, as prices have fallen 90 percent in the last decade, and we expect to see adoption rates rise over the next several years.

Chad Hall ( is founder and a vice president of sales at Ioxus, Inc., focusing on European sales. His extensive mechanical engineering and business experience helped establish Ioxus from funding to factory to launch.

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