Forklift Batteries: Conventional vs. Opportunity vs. Fast Charging
Modern technology has influenced the lift truck in many ways, including the batteries that power them. One of the most significant demands of the supply chain is speed, combined with efficiency. Hence the need for longer running forklifts has led to opportunity and fast charging to speed up the lead-acid battery charging process. This method also helps eliminate some of the labor and maintenance associated with conventional charging. Is opportunity charging and fast charging a good fit for your operation? Let’s take a look at the differences between conventional, opportunity, and fast charging processes.
For much of the time, conventional charging was the only way to keep a forklift battery running. In this process, a forklift runs until the battery is drained of power. The battery is then changed out from the forklift. They are removed and then connected to a charging system that involves charging and cooling. After that, the forklifts are put back into operation. This charging style generally follows the "8-8-8 rule," which means that the battery will discharge over eight hours, recharge over eight hours, and be cooled for eight hours once charged. 
The process generally requires a designated battery space or “battery room” where charging and other maintenance activities are performed. In some facilities, this takes up a large designated area that can be put to better use.
Opportunity and Fast Charging
With advancements in technology came quicker, more advanced battery charging known as opportunity charging and fast charging. This process provides forklifts with shorter charging times and allows them to run longer throughout the day to increase productivity. When utilizing opportunity charging, the battery remains in the lift truck and is plugged into a charger. Large facilities often have banks of charging stations for this purpose. Charging can be done throughout the day at break time, lunchtime, or whenever the "opportunity" arises.
Fast charging is a similar procedure as the batteries are not removed from the lift truck. It differs in the amount of current you're putting back into the battery at the start of the charge. Speeding up the charging process happens at the beginning of that cycle. A faster start rate accelerates the charging process so that you get more use out of your equipment per shift.
As an example, consider a 1,000 amp-hour battery. The start rate for conventional charging is about 20 percent, meaning that you're putting 200 DC amps back into that battery at the start of the charge. The start rate for opportunity charging is about 25 percent, meaning that you're putting 250 DC amps back into the battery at the start. The start rate for fast-charging applications is 35 percent or more. 
The advantages of opportunity and fast charging are cost savings, higher productivity, safety, and maintenance improvements. However, there is a tradeoff with both methods, and it can outweigh the benefits if the conditions aren't right, and that's reduced battery life. The life of a lead-acid battery is limited. Opportunity and fast charging won't change the amount of time a battery has. It can accelerate the process by exposing the battery to more heat, which can wear it down faster.
Evaluating the pros and cons of conventional charging, opportunity charging, and fast charging can be complicated. We suggest a power study be done to determine the best option for your operation. The study can help you learn about your forklift utilization, energy consumption, and charging opportunities in order to assess your operation's best charging method. For easy reference, download this Battery Charging Methods Chart from Crown Equipment.
At Action Lift, our material handling experts are ready to analyze your motive power needs. Contact us at 570-655-2100.