BY Larry Carley

The battery is one of the most important components on a vehicle. It provides the amps needed to crank and start the engine, and stores the voltage that runs everything from ignition system and fuel injectors to the vehicle?s lights and all of its electrical accessories.

Lead-acid batteries have been around since the earliest days of the automobile and are still used today because lead is relatively cheap, easy to manufacture and recycle. The basic design of a lead-acid battery is relatively simple and works well enough for the demands that have been placed upon it so far ? but that may soon change.

California?s recent decision to stand firm on requiring auto makers to market Zero Emission Vehicles (ZEV?s) in 2003 means new batteries, with higher energy densities and shorter recharging times, will have to be developed to power these vehicles. Nickel-metal-hydride, lithium-ion, lithium-polymer and high temperature sodium-sulfur are all alternative battery technologies that are vying to replace lead-acid in ZEV applications. All are capable of providing higher energy densities than lead-acid and can extend the driving range of ZEV vehicles. But high manufacturing costs are still a major obstacle for most of these new battery technologies.

Another factor that is driving battery development today is a desire to boost fuel economy. One way significant gains can be realized is to replace conventional belt-driven accessories, mechanical and hydraulic systems with electronically controlled and powered devices. Electric-assist power steering, currently offered in only a few exotic cars, could eliminate bulky power steering pump, hoses and fluid leaks while reducing the horsepower drain on the engine. Other innovations now include fully electronic brake by wire systems, electrically driven A/C compressors, and even electrically operated engine valves.

One approach that could yield a 15 to 30 percent improvement in fuel economy in city stop and go driving is a system that combines the starter and alternator into one and makes it part of the flywheel. This not only eliminates the weight, cost and bulk of an engine mounted starter and alternator, but also allows the engine to be momentarily turned off while waiting at a traffic light.

These new technologies are not being used toady because most require higher operating voltage to be practical. Twelve volts does not provide enough ?oomph? to power some of these devices, so engineers are looking at higher voltage batteries and electrical systems.

Starting in the 2003 model year some European vehicles will be equipped with a ?next generation? 36/42-volt electrical system that packs the extra punch needed to make these new technologies practical. The domestic vehicle manufacturers are expected to follow suit, and many experts predict 36/42-volt batteries and electrical systems will gradually replace 12-volt systems over a 6 to 10 year transition period. Time will tell but it is likely more volts will be available under the hoods of tomorrow?s vehicles.

The 36/42 notation refers to the battery voltage (36v) and the charging system?s output voltage (42v). Today?s vehicles, by comparison, have a 12/14 system: a 12-volt battery and a charging system that typically produces about 14 volts.

Some vehicle manufacturers are also looking at ?dual battery? systems that would assign specific jobs to two separate batteries. One battery would be optimized for high demand loads like cranking and starting while the second battery would power electronics and other low-amperage accessories. This approach would also allow a vehicle to have separate electrical systems: a high voltage 36/42 volt system for cranking and starting and other high load demands, and a separate 12 volt battery for lights and electronics.

The appearance of more hybrid electric/gasoline and electric/diesel vehicles, offering exceptionally high fuel mileage and extremely low emissions, is also spurring the development of advanced battery design.

Hybrid vehicles don not require a ?deep cycling? battery that can be repeatedly discharged like a fully electric vehicle because the engine drives a generator that keeps the battery fully charged. Battery power is only needed to start or restart the engine, and during certain driving modes as when accelerating, passing, driving uphill or pulling a load.

The appearance of new battery designs and technologies will depend on how quickly other new vehicle technologies are introduced and what direction they take. Meanwhile, technology going into today?s aftermarket replacement batteries continues to improve as a spin-off from many of these other trends.

Another innovation that has been gaining momentum is the use of a ?gel? electrolyte or ?recombination? technology in some batteries. With this approach, there is no free liquid inside the battery. The acid is contained in ?Absorbent Glass Mat? (AGM) separators between the plates. The separators hold the acid much like a paper towel soaks up water, making the battery ?spill proof? even if the case is punctured. A battery with AGM separators can be shipped by normal means (no spillage), and installed in any position. AGM separators provide extra cushioning and are more resistant to vibration damage (a leading cause of battery failure).

Over the years, a number of batteries with special features have been introduced. The most recent approach to preventing a dead battery is to incorporate a sensing circuit in the battery that disconnects the battery if a power drain is detected after the key has been turned off.