Design Con 2015

Product How-to: Extending battery life in transportation and mobile applications with supercapacitors

Jason P Lee, Global Product Manager, Eaton Bussmann -December 11, 2013

With battery life rising in prominence as one of the most critical areas of system performance and reliability, the introduction of supercapacitors is helping to extend life of batteries in two major application areas. First, they can dramatically reduce battery replacement costs in vehicles such as trucks, cars, ships and motor generators. Second, they can extend the run time as much as 400 percent in mobile devices such as smartphones and tablets.


Supercapacitors, or supercaps, with their unlimited recharging capability and high energy density, provide automotive, heavy transportation, marine and traction applications with guaranteed engine starting over broad temperature range even when a battery fails.


In mobile electronic systems, supercaps provide the ability to regulate peak current over several different application usage scenarios.  With better regulation of the discharge, the batteries are able to hold their peak capacity of energy longer and extend the run time of devices.


Examining the market needs of both application areas demonstrates that the benefits of adding super capacitors but in critically different ways.


Engine Starting


The most critical factor in the transportation sector is engine starting reliability. Every time a lead-acid battery is used to start an engine, it is one step closer to end-of-life. Using a bank of supercapacitors for ignition system relieves the battery from the harsh discharging of engine starts that typically diminish life span.  A typical lead-acid battery can have its useful life extend by as much as 70 percent in certain applications through the use of supercaps. Additionally, starting an engine off a supercap enables greater reliability in colder temperatures.


In the case of the trucking industry, there are several factors where super capacitor usage could help improve daily operations. Typically, 18-wheel tractor trailer rigs and passenger buses carry three to four batteries. When one battery fails, and the vehicle requires a jump start, it can be relatively expensive at a cost of $600 per incident.


Additionally, battery replacement costs are about $200 each and because of this, market research shows that battery theft in both trucks and buses is a problem area.  Furthermore, starting reliability for lead-acid cells drops precipitously in temperatures below -10° Fahrenheit. Supercaps, on the other hand can extend that range to -40° F, further improving engine start reliability where cold weather conditions prevail.


In the case of motor generators that are generally used at construction sites where grid power is unavailable, 60-to-80 percent of engine failure is due to bad batteries, according to market research conducted by Cooper Bussmann. Battery theft is also a significant issue, research shows.


Locomotives must operate reliably and operate in all conditions to meet very demanding train schedules. Cold weather is one of the most prevalent operation conditions and super capacitors can enable engine starting at -40° degrees Fahrenheit, whereas lead-acid batteries aren’t reliable below -10 ° F.


Engine starting for boats is critical because they operate in conditions where jump starts aren’t readily available, and where environmental conditions such as storms or strong tides demand reliability. Additionally, other electrical systems on the boat for electronic equipment (fish finders and navigation) place a considerable load on lead-acid batteries when the engines aren’t running.


In cars, emission regulations will drive automakers to install stop-start systems.  It is forecasted that 40 to 70 percent of new vehicles by 2017 will have stop-start. Requiring a car’s engine to automatically turn off after an idle period will require numerous more restarts that will strain lead-acid batteries and shorten their lifetime. Today, most vehicle manufacturers install a second battery to ensure reliability of stop-start systems.


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