Lift Trucks: Lithium Batteries Enable On-Board Charging
Lead-acid batteries have long played a crucial role in powering lift trucks. However, while such technologies helped pave the way, they were only a stepping stone.
In the years since their introduction, new battery technologies have emerged. Modern lithium batteries offer greatly enhanced capabilities. For one, their far superior power density is instrumental in reclaiming enough space to outfit lift trucks with on-board chargers.
Moreover, the efficiency gains, maintenance simplicity, and access to telematics data that lithium batteries, on-board charging, and battery management systems (BMS) achieve are some of the biggest advancements in lift truck capabilities today.
Drawbacks of Traditional Lead-Acid Batteries
For decades, lead-acid batteries have been commonly used in various industrial applications, including lift trucks. Compared to alternative power sources, their high power-to-weight ratio and relatively low costs made them a suitable choice for motive applications.
But while their affordability and simplicity will likely ensure they retain some market share for a few decades more, battery technology advancements have progressed enough that using lead-acid has hindered more sophisticated operations.
Today’s lead-acid batteries rely on technology that’s over 150 years old. In that time, there’s been little significant development besides the introduction of gel electrolyte and absorbent glass mats (AGM) with sealed lead-acid batteries.
As a result, today’s lead-acid batteries are still:
- Legacy technology – Lead-acid batteries are incompatible with today’s data-driven operations, and they’re incapable of collecting and exchanging relevant data and telematics. In contrast, lithium batteries and integrated smart technologies (e.g., chargers and battery management systems) enable operators and fleet managers to optimize maintenance schedules and resource allocation based on recent and historical performance data.
- Heavy – Lead-acid batteries are quite bulky and heavy, with some weighing between 800 to 4,000 lbs. The size and weight have forced OEMs to engineer their lift truck designs around the battery instead of slimmer profiles for greater maneuverability or more ergonomic configurations to better support operators. Moreover, the batteries are difficult to repair or replace.
- Limited capacity – Lead-acid batteries have a relatively low energy density, meaning they can’t store as much energy in a given volume. As a result, the greater the energy requirements, the larger the battery must be.
- Low efficiency – Lead-acid batteries tend to lose significant energy during charging and discharging, which can shorten their life span and increase the need for frequent charging. Traditional flooded lead-acid batteries are only 80% efficient, and sealed lead-acid batteries are only 85% efficient. In comparison, lithium batteries are 95% efficient and provide a roughly four times longer life span.
- Watering – Lead-acid batteries must be regularly watered, which increases total maintenance costs.
Lithium Battery Performance Advantages
Lithium batteries are the future of rechargeable batteries. Compared to lead-acid, lithium batteries charge faster, require zero cool down, have longer life spans, and offer enhanced energy efficiency, deeper discharge depths, and opportunity charging support.
The only performance disadvantages lithium batteries contend with are weight reduction and upfront cost. Lead-acid batteries help counterbalance lift tricks when transporting heavy loads, so OEMs might employ a simple solution of adding weight (e.g., metal plates) to offset that loss. And upfront costs have sharply fallen over the last few decades while lithium batteries’ total cost of ownership is lower (given performance and lifespan).
Specifically regarding on-board charging capabilities, lithium batteries’ most significant advantage is their greater power density. This results in smaller, lighter batteries delivering equivalent energy compared to lead-acid options. With weight and space reclaimed, OEMs can now add additional on-board functionality.
High Power Density
Lithium battery technology inherently provides a high power density ratio, which allows it to store a large amount of energy in a small volume. As the Clean Energy Institute from the University of Washington notes:
“They have one of the highest energy densities of any battery technology today (100-265 Wh/kg or 250-670 Wh/L). In addition, Li-ion battery cells can deliver up to 3.6 Volts, 3 times higher than technologies such as Ni-Cd or Ni-MH.”
Benefits of On-board Charging
The physically smaller lithium battery creates enough space for robust on-board chargers capable of meeting shock, vibration, and other environmental demands. This, in turn, creates three specific operational advantages for fleet managers:
- Improved battery and operating system control – On-board charging provides greater flexibility and adaptability than off-board options. For example, there are fewer parts and equipment to keep track of or maintain—a major benefit for rental companies and facility operators that may need to move lift trucks between locations.
- Telematics data for battery and charging – On-board chargers can easily integrate with the BMS, CAN bus systems, and, by extension, warehouse management systems (WMS). Equipped with real-time charge data monitoring and analysis, teams are better prepared to make informed decisions to prevent costly repairs and optimize charging and usage practices.
- Better opportunity charging support – For years, the largest barrier to opportunity charging capabilities was that the battery had to be removed and attached to an off-board charger. But lift trucks can be charged whenever and wherever possible with rapidly charged lithium batteries and on-board chargers.
Operational Advantages
It’s not just performance that makes lithium batteries a better option than lead-acid batteries. From a fleet management perspective, lithium batteries offer several operational advantages. This is because the typical requirements for operating a fleet of lead-acid battery lift trucks include:
- Space requirements – Lead-acid batteries traditionally required full rooms dedicated to charging and storing the batteries, adding a space premium.
- Cool-off periods – Because of discharge levels, lead-acid batteries often require a cool-off period. As a result, a lift truck operator may need to have and switch between two batteries on-board, which increases weight and eliminates usable space for elements like an on-board charger.
- Maintenance needs – Lead-acid batteries have hefty and frequent maintenance requirements. For instance, the batteries must be regularly watered, which slows operations down and poses a safety hazard for workers.
Many of the above concerns are mitigated with lithium batteries, if not entirely eliminated. They don’t require dedicated charging rooms, frequent maintenance, or any cool-off, which allows the lift truck to work longer and harder while costing less.
Put simply, this enhanced battery technology and the on-board charging it enables prevent many of the operational issues that might impact a company’s bottom line, customer satisfaction, and reputation.
Lithium Batteries and On-Board Charging—The Future of Lift Trucks
The transition from traditional lead-acid batteries to lithium batteries is the most significant impact on the lift truck industry in decades.
The smaller, more powerful lithium batteries offer a range of performance and operational benefits, including the ability to use on-board chargers. This allows lift trucks to be charged more conveniently while improving the overall performance and efficiency of the vehicles.
Sources:
HyTek. What are Lead-Acid Forklift Batteries? https://hy-tek.com/resources/lithium-ion-vs-lead-acid-forklift-batteries-which-is-best-for-you/
Clean Energy Institute: University of Washington. What Is a Lithium-Ion Battery and How Does it Work? https://www.cei.washington.edu/education/science-of-solar/battery-technology/
