Ultracapacitors 101: Continuation of: What Do Those Words We’re Using Even Mean?

We have had two previous discussions for the terms used in the ultracapacitor arena, providing an overview of how the technology works and defining some of the terms. This blog post is a continuation of the definition of terms in an effort to create a glossary of key terms in the ultracapacitor space. Understanding the technology helps, but you won’t be able to compare products without a clear understanding of the related terminology.

Check out the definitions of must-know ultracapactior terms below and tweet us @ioxus with your questions. Don’t forget to also let us know what you think of this series and offer suggestions for other topics.

Module: in discussion of ultracapacitors, a module is a self-contained assembly of several cells, which can be installed as a unit. Many applications require higher voltages than what is offered by a single cell, so modules are often used for an easier installation process. Modules also contain cell balancing, which ensures that each cell shares a very similar voltage as its neighbor, allowing for longer product life.

Energy Density: the amount of energy stored per unit of volume. Energy density is often measured in Megajoules (MJ) per kilogram or in terms of watts (Whr).

Power Density: the amount of power per unit of volume. Power density combines energy density with the speed at which the energy can be delivered to the load. Due to their physical structure, ultracapacitors have a much higher power density than batteries – around 10-100 times larger. Power is often measured in Kilowatts (KW) or Megawatts (MW) per kilogram.

Equivalent Series Resistance: resistance in an electrical conductor. As we see with ultracapacitors, this is the force that opposes the passage of an electric current through the conductor. The lower the equivalent series resistance, or ESR, of an ultracapacitor, the more efficiently a capacitor can charge or discharge while creating lower heat.

Thermal Resistance: a measurement used to determine the heat generation during a cycle within the ultracapacitor.

Endurance: there are two types of endurance measured relating to ultracapacitors:
• Capacitance Endurance measures the maximum capacitance change expected if the ultracapacitor were to operate at the upper operational limitations outlined for the particular product.
• Resistance Endurance measures the maximum resistance change if the ultracapacitor were to operate under the same conditions.

Cell Balancing: the process that reduces the voltage spread in cells. Voltage spread is natural, the result of one of several factors, including an imbalance in leakage currents, an imbalance in capacitance or an imbalance in power losses from ESR. This balancing process ensures a long cycle life for the ultracapacitor.

Leakage Currents: the small amount of discharge from an ultracapacitor, resulting from variations in materials and manufacturing. This discharge over time can result in a voltage spread, which, in some cases, is significant.

Inductance: the process by which a change in current in a conductor creates a voltage in both the conductor and in nearby conductors. Ultracapacitors have low inductance, which enables the ultracapacitor to have a very high power density and a fast rise time, which is simply the time it takes to change from a low voltage value to a high voltage value.

Latest News

  • uSTART® Lead-Free Replacement for Truck Batteries

    ONEONTA, N.Y.Jan. 9, 2019 /PRNewswire/ -- Ioxus uSTART® has received two fleet industry awards for sustainability by eliminating lead-acid batteries with its ultracapacitor-based, drop-in battery replacement.

    "With uSTART, fleets not only realize the benefits of improved starting reliability, there are equally important and real sustainability improvements from lead waste reduction," said Chad Hall, executive vice president and co-founder of Ioxus. "By replacing one of the batteries on a vehicle with a uSTART module, up to 15 fewer batteries are needed over the lifetime of the vehicle. This translates into 1,000 pounds of lead that will never need to be disposed of or allowed to affect groundwater."

    EU legislation on batteries is embodied in the European Battery Directive.  Its objective is to contribute to the preservation and improvement of environmental quality by minimizing the negative impact of batteries and battery waste.  As these preservation efforts expand, sustainable technologies develop to manage and mitigate these risks.

    Replacing a lead-acid battery with uSTART in a typical commercial vehicle creates measurable environmental benefits:

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