Transit vehicle batteries originally designed solely for starting are increasingly burdened with auxiliary loads for everything from fare boxes, GPS, destination boards, lighting and heating to air conditioning and security CCT V systems. In addition, voluntary and mandated efforts to reduce CO2 emissions and improve fuel economy are resulting in greater numbers of transit vehicles being equipped with start-stop or anti-idle engine systems.

Start-stop engines automatically shut off when the vehicle is at idle during pick-ups and drop-offs and restart when the driver ’s foot leaves the brake pedal saving fuel and reducing emissions. During this time, the energy needed to power the vehicles total electrical system is provided by the battery rather than the engine alternator.

While this saves fuel and reduces emissions, batteries now support tens of thousands of starts annually vs. a few hundred a few short years ago and are required to support hundreds of millions of micro-cycles as electrical loads run off of the battery instead of the engine and unlike in the past when batteries were maintained in a fully charged state and charged over time, vehicle batteries today are constantly operated in a partial state of charge and must support rapid recharging between engine on-off periods. This requires traditional starting batteries to be upgraded and in some cases the addition of auxiliary battery banks to supply the key-off off loads to guard against Monday morning no-starts.