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Group 31 AGM is the only way to go Batteries must match growing demands from greater electrical loads By Brad Bisaillon Shrinking budgets paired with the pressure to remain profitable are challenging transit agencies and bus companies to do more with less in the wake. Ensuring the reliability of bus fleets and maintaining low operating costs have resulted in executives more closely scrutinizing bus designs and operating components such as battery technology. The latest bus models incorporate technology that requires a greater reliance on batteries to supply increased electrical loads to operate such components and accessories such as fare boxes, fire suppression systems and security and surveillance equipment. These new electrical systems put a tremendous strain on the batteries and have caused traditional flooded batteries to prematurely fail. Maintenance crews are quickly realizing the importance of selecting the right type of battery to effectively manage these more strenuous electrical loads, as well as provide the power to start buses that may have sat idle in the storage yard. Group 31 AGM batteries are proving to be the best choice for today’s mass transit bus and motorcoach operations. This new technology better handles the deep discharge inherent in these applications while retaining the capability to start the vehicle. This is a shift from 8D and 31 flooded lead acid batteries which were not able to sustain the continuous strain of electrical systems that now require power 24/7. Not all AGM batteries are the same. There are significant differences in the construction and performance characteristics that determine the ideal
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regulator setting to maintain the health of the battery and gain maximum life. Onboard systems like engine ECMs, Vansco and I/O Controls prevent the regulator from being adjusted to any higher than 29.0 volts, narrowing the field of AGM batteries that best suit particular applications. Not all AGM batteries will survive at a charge voltage rate as low as 29.0 volts. Selecting the wrong battery technology could result in dramatically reduced battery life by delivering too high a current at too low a voltage, causing premature failure and unnecessary downtime, which can be costly and detrimental to a transit line’s on-schedule record. Supercapacitors (also known as ultracapacitors), when used in
conjunction with deep-cycle AGM batteries, provide effective power storage and ensure successful engine starting. Ultracapacitors can deliver their storage electrical energy at a high crank rate in a variety of extreme temperatures to provide reliable and consistent starting. Some bus fleets are adopting supercapacitor technology for cranking applications and then employing AGM battery technology to manage auxiliary loads. Implementing deep-cycle AGM batteries eliminates the need for the routine maintenance required for flooded 8D battery technology. While AGM batteries are sealed and do not require the addition of water, they do “off gas” and should have good ventilation.
Trojan’s TransPower deep-cycle batteries are used in Gillig buses in service at TheBus, which is operated by Oahu Transit Services in Hawaii.
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