If you are a business owner or manager who depends on forklifts to operate your business, the type of industrial battery you choose will have a major impact on your company’s overall efficiency – and that is true if you have just one lift truck or an entire fleet of forklifts in use. Depending on which type of electric forklift battery a business chooses, a lot of time and money could be saved over the long run.
This guide will walk you through the different kinds of forklift batteries, their key differences, forklift battery price ranges, and how these battery options will impact the overall efficiency of your business’ daily operations.
After determining which size battery is compatible with your forklift, the next important consideration is using: lithium-ion vs lead acid forklift batteries.
Electric forklifts are generally powered by either of these two main types of batteries:
Lead acid
Lithium-ion
While there are other power options for forklifts, such as propane or diesel, or gas power, 2/3rds that are put into service each year are electric.
The technology behind each of these industrial batteries differs greatly, and therefore, has a different impact on forklift efficiency.
Lead acid batteries are the old-school standard for powering forklifts. They are bulky, liquid-filled units with a removable top that generates electricity via a chemical reaction of lead plates and sulfuric acid. Its technology goes back to 1859 and involves regularly refilling the units with water (which is also necessary for the electricity-generating chemical processes happening within). Lithium-ion batteries are a newer technology, having been first used in a commercial product in the early 1990s, a Sony camcorder. Lithium-ion batteries have many different chemistries. One of the most popular chemistries for the material handling industry is lithium iron phosphate (LFP). It is more compact and energy dense than lead acid. The cells are sealed shut and require no water maintenance.
Length of a Forklift Battery’s Service Life
Like any business expense, electric forklift batteries are a cost that needs to be dealt with regularly.
Which type of battery a company uses in its forklifts determines how often workers will have to replace the battery. Lead acid and lithium-ion batteries have different lifespans:
Lead acid: 1000 - 1500 cycles
Lithium-ion: 3500 cycles
These are averages and may vary based on how well the batteries are maintained.
A lithium-ion forklift battery needs to be replaced less frequently, which is a major driver for business owners to prefer them to conventional lead acid batteries – which need to be replaced out for new ones more often.
Maintaining Forklift Battery Capacity
Both lithium-ion batteries and their lead acid counterparts should be cared for properly if they are to perform up to their full potential. Their service life will diminish if proper forklift battery maintenance is not carried out as it should be.
In order to maximize service life and overall battery capacity, certain measures should be taken for users of both battery types. However, lead acid batteries require more care and attention compared to lithium-ion.
Lead acid forklift batteries require:
Equalizing (Cell Balancing): Traditional technology like this leads to a frequent state where the acid and water inside become stratified (separated horizontally with the acid more concentrated closer to the bottom). This state forms sulfate crystals towards the bottom of the cells and weakens their ability to hold a charge. Equalizing will break up the sulfate crystals but if the battery has been neglected for too long the crystals will not break.
Temperature Control: Lead acid batteries must be kept within a certain temperature range, or else they will have a shorter working life. On top of that, they also get very hot while charging, which requires them to be charged and stored in a temperature-controlled space.
Fluid Level Management: These types of units must be checked to ensure they have enough water about once every 10 or so charging cycles.
Lithium-ion batteries are much less needy when it comes to forklift battery maintenance, as they equalize automatically, function well in much higher temperatures (making temperature mostly a non-issue), and do not require any fluid level management.
For comparison:
Cell Balancing: The equalization of voltages and state of charge among the cells within a battery when they are at full charge. This is a practice that preserves the capacity of a battery pack with multiple cells.
Battery Capacity: How much current can be drawn from a battery. Capacity is measured in units of amp-hours (Ah).
Lead Acid Battery: A rechargeable type of battery that contains lead plates immersed in a sulfuric acid solution. The chemical reaction creates an electrical current used to power equipment.
Lithium-Ion Battery: A rechargeable type of battery that contains lithium ions which move through an electrolyte to create electricity to power equipment. Unlike lead acid batteries, the electrolyte is permanently sealed in a lithium-ion battery pack.
Thermal Runaway: When heat generated in a battery exceeds the amount of heat that is dissipated to its surroundings. In batteries, this occurs when a cell exceeds a specific high temperature which varies by chemical composition, because of thermal failure, mechanical failure, short circuiting, or electrochemical abuse.
Electric Forklift: A forklift that is powered by a battery, used for handling materials in warehouses, distribution centers, etc.
Battery Efficiency: The amount of energy that a battery delivers compared to the amount of energy that is put into it during charging. Factors that affect battery efficiency include charge current, resistance, battery temperature, and battery age.
Battery Discharge Rate: The amount of current divided by time it takes to discharge a battery. It is defined as the stable current in amperes (A) that is taken from a battery of specified capacity (Ah) over a period of time.
Battery Lifespan: How long a battery can operate during its life. Lifespan is measured by the number of charge and discharge cycles it has until the end of its life.
Battery Electrolyte Level: Battery electrolyte is the liquid substance that is found in lead acid batteries. The battery electrolyte is made up of water and sulfuric acid and is known to be highly corrosive. An important part of lead acid battery maintenance is checking the battery electrolyte levels to see if it needs to be topped off using distilled water. This process helps to prolong the lead acid battery’s life.
When it comes to electric lift vehicles, forklift battery specifications are not the same across the board. Forklift battery weight, size and voltage vary substantially, depending on which type of vehicle they are powering.
Generally speaking, forklift battery packs are chosen based on the type of lift equipment and the use case needed for the operation. With different types of electric equipment, there are typically four voltage options:
24V forklift battery
36V forklift battery
48V forklift battery
80V forklift battery
A 24V forklift battery would be appropriate for some of the smallest types of electric lift equipment, such as:
End riders
Center riders
Walkie stackers
Walkie pallet jacks
Meanwhile, 36V forklift batteries are designed for mid-sized electric equipment, like:
Narrow aisle forklifts
3 wheel sit-downs
The 48V forklift batteries are designed for large electric equipment, like:
Counterbalanced forklifts
3 wheel sit-downs
The 80V forklift batteries are designed for heavy electric equipment, like:
Large counterbalanced forklifts
Counterbalance Forklift: These forklifts have substantial weight (or ballast) added to the rear of the forklift to keep it stable when lifting a heavy load. They can handle a capacity of 8,000 lbs. or more, making them essential when lifting heavy materials throughout a facility.
Narrow Aisle Forklift: Found in operations that want to maximize their storage space. This lift truck typically has a tighter turning radius.
Forklift Battery Size: Size can vary based on the type of equipment being used as well as how much voltage and capacity is needed.
Forklift Center of Gravity: The point on a forklift at which all the forklift’s weight is concentrated. It is important to distribute weight evenly to keep the forklift stable.
End Rider Forklift: End Riders have minimal lift capabilities (i.e. lifting a pallet off the ground) and are used to transport materials throughout a facility.
Walk Behind Pallet Jack: Designed to lift loads between 2,000 - 8,000 lbs. They are commonly found in delivery trucks for efficient loading and unloading of materials.
Battery Weight: A battery with a specific voltage & capacity will often be available in varying weights to meet the different forklift manufacturer’s requirements
Battery Charging Time: The amount of time required to fully charge a battery’s discharged cell.
Battery Voltage: The difference in electric potential between the positive and negative terminals of a battery.
Forklift Turning Radius: Depending on the type of forklift the turning radius can vary. This is a key feature that is part of the forklift design.
How an electric lift truck’s battery is recharged for continued commercial use has a major effect on how efficiently a business can operate, especially if there are any battery charging station requirements.
As you can imagine, lithium-ion batteries are the newer of the two types of battery technology, so their charging is faster and less complicated. Let us take a look at how charging is different between these two forklift battery types:
Lithium-ion batteries can be opportunity charged and do not need to be recharged to 100% forklift battery capacity.
Lead acid batteries must not be disconnected from their forklift battery charger until they have reached full forklift battery capacity and in most cases cannot be opportunity charged.
Moreover, if either of these types of batteries are not charged correctly, they will deteriorate in quality as time goes by – with lead acid units having much stricter guidelines when it comes to the required charging technique.
Forklift Battery Charging Station Requirements
The physical location of your forklift battery charger system is a much bigger consideration than many business owners realize.
Lead acid batteries have specific forklift battery charging station requirements that lithium-ion battery packs do not. After all, lithium-ion battery packs are plugged straight into a charger, and they do not need to be removed from the lift truck to start recharging. There are not really any further actions that need to be taken in order to do a simple recharge.
With lead acid forklift batteries, however, the units must be removed from the vehicle completely and placed onto a separate forklift battery charger – many of which have the ability to perform equalization. If there are many forklifts in operation, then there will need to be multiple chargers as well as a space for multiple units to cool down after fully recharging. This will involve employees having to use special lift equipment to pick up discharged batteries and drop in charged batteries on a regular basis. While it is not physically straining the task is time-consuming to operations wanting to be more productive.
Lead acid batteries need a dedicated charging space that ventilates and controls the temperature in the room. This is because lead acid batteries can get very hot while charging, producing harmful fumes.
Lithium-ion forklift batteries do not need a separate space, do not need to cool down, and do not require a fully-charged spare at the ready when another one fully discharges – it can be recharged on the spot.
Opportunity Charging: The practice of using natural periods of downtime, like operator meal breaks, to charge the battery for short periods of time throughout the day. This allows operators the continuous use of the same battery throughout multiple shifts.
Overcharging Battery: Overcharging a battery is charging a battery more than its designed capacity. This can create unstable conditions inside the battery, increase pressure, and cause thermal runaway. This can be damaging to the battery, the equipment, and the operator.
Battery Runtime: The length of time a battery charge will last while the forklift is in use.
Industrial Battery: A battery designed for industrial equipment use. Typically, these batteries will be subjected to harsher use conditions than a battery designed for consumer use.
Fast Charging Battery: A battery capable of charging faster than conventional charging standards. Typically, a battery pack will use a charger that has the capability to speed up the battery charging process.
Forklift Battery Charger: Feeds an electric current through a battery for a specific period of time.
Constant Current Constant Voltage (CC CV): A charger regulates the amount of current until the battery reaches a set voltage. Once the battery reaches the set voltage, the current is reduced.
Sulfation: The build-up of lead sulfate on the surface of a lead acid battery. Sulfation happens when a battery is not maintained. If left unattended, lead sulfate build-up can cause the battery to stop working.
Battery Plates: Positive and negative plates that generate electricity. The individual cells of the battery fit into these plates to create a chemical reaction that helps produce voltage.
Equalization Charge: Overcharging the battery after a full charging cycle at a higher-than-normal voltage. This step is necessary help remove built-up sulfate and balance the voltage of each cell in lead acid batteries.
It’s not just the charging that requires close attention and regular checks – the fluid inside of lead acid batteries involves regular work.
Lithium-ion batteries are sealed shut, and the electricity-generating chemicals inside will stay inside, requiring no liquid-related effort by forklift operators.
Lead acid batteries are quite the opposite, on the other hand, and require an entire forklift battery watering system that employees must learn to abide by if they want the battery to function well for its maximum possible service life.
The lead acid forklift battery watering system involves:
Only topping off with water when it’s fully charged and cooled down
Refilling water often enough so that the top of the lead plates is never exposed, which is approximately every 10 charge cycles
Being careful not to overfill with water
Leaving enough space for the liquids inside to expand, which happens when the battery is in use
Use water between 5 and 7 on the pH scale
There are battery water monitoring systems that can automatically let you know when water needs to be added, or it can be done by checking it yourself.
There are also battery watering systems that automatically add exactly the right amount of water, which can also be done manually.
Battery Watering: An important part of lead acid battery maintenance which is necessary to keep the battery functioning. Watering a battery, helps keep the electrolyte levels from overflowing after being charged. This helps prevent acid-related and overheating damages. Gassing also causes water loss which is why battery watering is necessary.
Battery Corrosion: The electrochemical reaction between metal and its environment that causes the battery material to deteriorate. Lead acid battery lead grids often corrode in service, which is an issue only lead acid batteries have. This usually leads to battery failure.
Lead Acid Battery Maintenance: Lead acid batteries require regular maintenance due to electrolyte levels decreasing during the discharge process.
Maintenance Free Battery: Batteries that are sealed and don’t require service or attention to electrolyte levels. Lithium-ion battery packs are sealed meaning they do not require regular maintenance.
Deep Cycle Battery: A lead acid battery that can sustain power over a long period of time until 80% discharged. “Deep cycle” means the level of discharge in comparison to other lead acid batteries that cannot sustain the same energy over a period of time.
Charge Cycle: The charge cycle refers to the process of charging a battery to full capacity, and then discharging the battery. That complete process is referred to as the charge cycle.
Overfilled Battery: A lead acid battery that gets over watered. This can cause electrolytes to dilute and diminish battery performance.
Battery Watering System: System created to fill all battery cells at the same time.
With such powerful chemicals involved, safety is of the utmost importance when handling both of these forklift battery types – though one of them clearly offers a safety advantage for a typical workplace. Let us examine lithium-ion vs lead acid forklift batteries as it relates to safety in the workplace.
Lead acid forklift battery safety risks:
Spills: The highly-toxic sulfuric acid within these batteries can absolutely spill out, especially since this type of unit needs to be watered about once a week. If watering is not done safely, employees will be at risk – which necessitates a chemical washing station in the workplace.
Overheating: These batteries get incredibly hot while they charge and can leak an explosive gas after reaching peak charge, making temperature control very important to safety. Forklift battery charging station safety must be carefully managed.
Dangerous Gases: If lead acid batteries are over-charged, specific hazardous gases can be released into the air. Add a room that is not well ventilated, and you have an extremely hazardous situation on your hands. The three main gases that can be released are hydrogen sulfide, hydrogen, and sulfur dioxide. If it smells like rotten egg, hydrogen sulfide is the likely cause, and employees should take immediate precautions. A standard catalytic LEL gas sensor should be installed in the charging room above the level of the gas. Or, measuring the hydrogen by means of a substance-specific electrochemical sensor. Since hydrogen is lighter than air, the sensor needs to be installed in the appropriate location.
Old or Corroded Batteries: Brand new lead acid batteries that are charged appropriately will not expose workers to the aforementioned conditions. However, old or corroded lead acid batteries are a real danger to the people working with them and should be properly disposed of immediately.
Lithium-ion forklift batteries are sealed, so there is no potential for acid spills, corrosion, sulfation, or any sort of contamination in the workplace. The chemical combination within these more-advanced batteries does pose a minuscule risk of expelling a corrosive gas when it comes in contact with water, but it is quite rare.
Warehouse Ergonomics: Having a functional warehouse environment that can mitigate safety risks, optimize operations, and lower costs.
Warehouse Safety: Rules & behaviors to protect warehouse employees from injury.
Battery Electrolytes: A chemical medium that allows the flow of electrical charge between the cathode and anode.
Automated Guided Vehicles (AGVs): Automated guided vehicles (AGV) are vehicles designed to perform material handling or load carrying without the use of an operator or driver. AGVs are guided by sensors, markers, tape, or wires in the facility and have a fixed navigational route.
Autonomous Mobile Robots (AMRs): Autonomous mobile robots (AMR) are more technologically advanced than AGVs. They move around the facility based on the most efficient path using sensors and cameras. AMRs can navigate around obstacles, adapt to its surroundings, and avoid anything in their way.
Battery Management System: The brain of the battery pack. It manages the operation of a battery pack. The BMS also allow users to monitor cells within a battery pack. It can provide the status and health of a battery.
Forklift Fleet Management: The best forklift fleet managers rely on a collection of data to see relevant performance information, such as state of charge, utilization, etc.
Industrial Battery Safety: Guidelines and precautions operators and technicians must take to ensure they are handling battery systems carefully.
Lead Acid Battery Off Gassing: A hazard of overcharging a battery. When a battery overcharges, the electrolyte solution can overheat cause hydrogen and oxygen gasses to form. This will increase pressure inside the battery leading to permanent damage.
On the surface, a lead acid battery may seem like the better investment than a lithium-ion forklift battery. That would be true if you only looked at the initial cost of buying a battery.
However, when prudent managers and supervisors take a deeper look at the total cost of ownership between lead acid and lithium-ion batteries, they see a far different picture.
Let's take a look at purchasing one (1) battery for a forklift and delve a little deeper into the actual numbers to see what the real cost of ownership is.
(These numbers are used as an estimate and actual prices may vary. They are only for demonstration purposes.)
The following return on investment calculation is based on a 5-year period:
If operations only look at the initial forklift battery price purchase, you would see slight savings when purchasing a lead acid forklift battery. When operating and energy costs are factored in the total, overall savings are quite significant for the lithium-ion forklift battery.
A total savings of $6.3M can be realized, per battery, over a 5-year period. If a fleet consists of 10 forklifts, that's a savings of $63M over 5 years.
More Energy Efficient With No-Water Maintenance and Increased Safety
For many managers and supervisors who are concerned with productivity, the no-water maintenance factor of lithium-ion batteries makes a switch from lead acid an easy decision.
The chart below shows how much more energy efficient a lithium-ion battery pack is for each battery pack offered.
The future of the material handling industry is on a path to reduced costs and environmentally-friendly technologies.
Warehouse Efficiency: Maximizing space, promoting productivity, and streamlining operations are ways to create efficiency in warehouses.
Operational Efficiency: The ability of an organization to reduce waste in time, effort and materials while producing a high-quality product. This can be gained though different processes, resource utilization, inventory management, and many other things.
Forklift Battery Price: The forklift battery price isn’t the true price because you have the initial purchase price along with the operating costs and energy costs that go with the battery. Lead acid batteries have a lower upfront purchase price but in the long run have a higher cost of ownership due to the required maintenance and higher energy costs. In comparison, lithium-ion battery packs have a higher upfront price but no maintenance costs, and lower energy costs, since they are more energy efficient.
Battery Energy Efficiency: The amount of energy available to ‘do work’ relative to the amount of energy that’s put into the battery through the charger.
Diesel Emissions Reduction Act (DERA): A program that funds grants that improve air quality by reducing the amount of diesel emissions produced.
Total Cost of Ownership: Total Cost of Ownership is a common method used to evaluate the entire cost over the lifecycle for a piece of equipment. In the case of forklift batteries, the Total Cost of Ownership includes the cost of maintenance and energy usage, in addition to the purchase price. It can also include the opportunity cost of something like a battery charging room, which might otherwise be used for production in a factory.
Unplanned Downtime: An unexpected shutdown of equipment. The cost of disruptions to production that come as a result of unplanned downtime often far exceed the costs associated with repairing the down equipment.
Labor Costs: A sum of all wages paid to employees. This cost can include employee benefits and payroll taxes paid by an employer.
Hidden Costs: Unseen expenses that come along with a purchase. One unseen cost of purchasing a lead acid battery are the energy costs.
Lost Productivity: The loss in revenue, production caused by the unavailability of an employee.
