A battery primer for electrical equipment, part 1: traditional technologies

A battery primer for electrical equipment, part 1: traditional technologies

Editor’s note: The following was contributed exclusively to Power Progress by battery manufacturer EnerSys, Reading, Pennsylvania, and edited for length and style. It’s part of a three-part series from EnerSys on understanding battery technology for electrical equipment and vehicles.

The internal combustion engine (ICE) has been a reliable workhorse since it was patented more than 200 years ago. However, the ICE has come under increasing scrutiny due to regulatory mandates on emissions, fluctuating fuel prices, expensive engine maintenance requirements and even health concerns over emissions. As a result, many OEMs are increasingly choosing a battery-electric (BE) approach for equipment such as forklifts and floor maintenance equipment.

Over the past decade, battery options on the market have expanded to meet a variety of industrial equipment applications, from traditional lead-acid batteries to more advanced options, such as lithium-ion and thin-plate lead-acid batteries.

To optimize fleet performance, OEMs and equipment managers must consider all aspects of the application before choosing the right battery. These considerations include power requirements, equipment lifespan, any equipment lease terms, and space limitations for maintenance and storage of spare batteries.

This first part of a three-part series of articles on the various battery technologies and their applications examines the traditional flooded lead-acid battery. This battery type continues to be a solid, proven and reliable technology used today for many different industrial vehicle and equipment applications. They have some performance limits, but are still considered a good option for many fleets.

Lead acid introduction

The traditional flooded lead-acid battery consists of lead plates immersed in a liquid electrolyte solution. They were first used to power the lights in railway cars in the late 1800s. Today they are the standard option for starting engines in highway vehicles such as cars, trucks and motorcycles.

EnerSys Ironclad wet lead-acid batteries are designed for a variety of material handling applications. (Photo: Enersys)

It wasn’t long before companies began testing batteries as the primary power source in industrial vehicles, and in 1906 the Pennsylvania Railroad introduced the first battery-powered platform cars for moving luggage at a train station.

As flooded lead-acid batteries became cheaper and more readily available in the 1990s, many major forklift manufacturers introduced new battery-powered machines for indoor material handling applications. The batteries are also commonly used to power floor maintenance equipment and commercial vehicles, such as electric carts, tractors and load carriers.

Proven technology

Traditional wet lead-acid batteries are a popular choice for industrial equipment because they have the most proven battery technology. They are also cheaper than other battery options and readily available from many battery manufacturers.

A variety of flooded lead-acid batteries are available, each offering different voltages, outputs and capacities to meet specific application needs.

Although highly reliable, these batteries have some drawbacks, such as limited energy storage density, making them better suited for lighter applications.

Power density

Flooded lead-acid batteries charge more slowly than other technologies. For industrial equipment and forklift applications, they are designed to be charged to approximately 20 percent before taking 10 to 16 hours to fully charge and cool down.

For heavier applications that cannot afford such a charging interruption, the batteries can be replaced between shifts. However, this is a time-consuming process that requires the purchase and storage of additional batteries.

More maintenance

Flooded lead-acid batteries typically require a higher level of maintenance than more advanced battery technologies. For example, water must be added weekly to the correct level. Watering too much or too little will cause damage and shorten battery life.

In addition, they must be regularly equalized by charging to a higher than recommended voltage. This removes sulfate crystals that can build up over time. Insufficient equalization can cause crystal formation, which reduces battery capacity.

Because this maintenance can lead to longer downtimes, many users choose to keep and maintain backup batteries.

Fast charging options

Fast-charging lead-acid batteries were introduced in the 1970s as the solution for heavy-duty equipment. They feature the same technology as traditional lead-acid batteries, but use improved inter-cell connectors and other components to enable faster and more aggressive charging.

The EnerSys Express wet lead-acid battery is designed for fast charging. (Photo: EnerSys)

The initial cost of fast-charging batteries is usually slightly higher than their traditional counterparts. They are most effective when used with express battery chargers, which are also slightly more expensive than standard battery chargers.

However, fast-charging batteries allow users to take advantage of opportunity charging during work breaks and other interruptions, minimizing the need for the longer charging periods required by traditional lead-acid batteries.

Because fast-charging batteries are used more intensively, good maintenance is even more important. For example, they still require leveling and adding water. They also offer lower energy density, making them best suited for medium-duty applications.

Fast charging batteries have an average life of 2 – 4 years depending on level of use and maintenance schedules. By comparison, a traditional wet lead-acid battery has a typical lifespan of 3 to 6 years, again depending on use and maintenance.

Part 2 of this series of articles will discuss more advanced battery technologies.