Today’s material handlers can choose from a selection of lead acid battery charging options that are more flexible and more efficient than ever before. Yesterday’s Ferroresonant (FR) and Silicon-Controlled Rectifier (SCR) charging technologies have given way to a range of High Frequency (HF) chargers that can meet several application demands, including conventional charging, opportunity and fast charging. Determining which charging method is best for your lift truck fleet is key to optimizing operational productivity and profitability. With that in mind, here’s a brief overview of how each charging process works and the kinds of operations in which it is typically used. 

Conventional Charging

Conventional charging generally involves the practice of charging the batteries for eight hours, cooling them for eight hours, then putting them back into service for eight hours. While some operations still do so with FR or SCR chargers, today, most get the job done with HF units that charge the batteries at a rate of 16-18A/100 Ampere hours (AH). 

In single-shift operations, conventional charging is an effective method, as operators can simply park the trucks and charge them overnight without having to remove the battery. But for multi-shift operations, conventional charging is a much more labor-intensive proposition – operators must remove the battery from the truck, place it into a rack in a designated charging room, manually connect it to a charger and then reverse the process as they put a freshly charged battery back into the truck. Conventional charging routines and battery changing is a technique still widely used for heavy-duty applications, where fast and opportunity charging just can't keep up with the higher energy demand.

Along with the time it takes to swap out and charge the battery, the overall process of conventional charging can be arduous. That’s because lift truck batteries are extremely heavy, with some weighing 2,000 pounds or more. Maneuvering them from the lift truck to the charging system is a daunting process, typically handled by a single operator using a battery extraction system. Most conventional charging methods also involve flooded lead acid batteries, for which mandatory Occupational Safety and Health Administration (OSHA) regulations require ventilation systems to disperse gassing, as well as equipment to flush and neutralize spilled electrolyte. All of these maintenance and regulatory requirements drive costs, as does the need to maintain more back-up batteries and a dedicated battery room that could otherwise be used for more profitable activities. Battery management systems can help mitigate some of these issues by enhancing battery charging and change-outs and by optimizing the number of batteries actually needed, but they also require an additional upfront investment. 

Opportunity and Fast Charging

As the name implies, opportunity charging involves charging the batteries whenever there is an opportunity – during breaks, in-between shifts or whenever it’s convenient. With opportunity charging, the batteries remain in the truck and are charged up to 25A/100AH. It’s an ideal option for any facility that uses its batteries consistently throughout the day, including high-energy, single-shift operations and extended- or multi-shift operations. 

Like opportunity charging, fast charging is performed throughout the day, however a fast charge rate is almost double that of an opportunity charge rate. Fast charging systems can recharge a flooded lead acid battery at rates of 40-50A/100AH and Thin Plate Pure Lead (TPPL) blocks at rates of 70A/100AH at every chance possible, making it the most beneficial option for multi-shift facilities.  

By allowing the batteries to stay in the truck, both opportunity and fast charging can eliminate the time-consuming daily maintenance of battery changing, charging and cooling, and also eliminates the likelihood of damaging cables, connectors and watering systems that come with conventional charging. Instead, operators simply pull the truck up to a charging station and plug-in whenever possible. They need only perform weekly and monthly services. Opportunity and fast charging batteries constructed with TPPL technology provide operators with a virtually maintenance-free power experience by removing the labor-intensive upkeep procedures tied to conventional charging, such as watering, cleaning and equalizing, and eliminating the need for a dedicated battery room. The reduced maintenance and inventory costs may be substantial, and the increased truck uptime may contribute to a better bottom line. 

Do Your Homework 

Ongoing advances in charger and battery technologies offer today’s material handlers several ways to reduce maintenance even while maximizing battery power and life. Along with doing some basic research, end-users often use a power assessment to determine which charging solution best meets their fleet operations and business objectives. Usually conducted by a battery and charger dealer or manufacturer, a power assessment provides a key first step in gathering the right information to achieve a lower Total Cost of Ownership (TCO) and overall convenience and productivity of operations.