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How To Choose the Right Forklift Power Solution
Understanding which motive power is right for your needs can be challenging. The three most popular solutions — lead acid batteries, lithium-ion batteries, and hydrogen fuel cells — each have their pros and cons. Often, the right solution depends on your exact needs, with a major consideration being whether your business model prefers a lower total cost of acquisition, a lower total cost of ownership, or maximized productivity.
Before you make a decision, you’ll need a quantitative analysis that looks at your processes, power use, and business planning. But a good first step is to understand the strengths and weaknesses of each solution, as well as their underlying technologies and how they work.
Power Motive Basics: Their Chemistry, Advantages, And Challenges
Lithium-ion and hydrogen technologies offer improved performance over lead acid in a number of important categories. However, especially in facilities already set up for their maintenance, advanced lead acid batteries remain competitive in material handling industries. They provide facilities with necessary forklift power without forcing them to pay for more capacity than they can use.
Thin Plate Pure Lead (TPPL) Batteries
The Basics Of A Lead Acid Battery
Inside the case of a lead-acid battery are positively and negatively charged lead plates, joined by lead connectors, immersed in an electrolyte solution of sulfuric acid. As the battery discharges, the sulfur in the electrolyte coats the lead plates, and in the process gives up electrons that become the electricity that powers the machine.
As the sulfate ions coat the lead plates, the electrolyte solution becomes more dilute. At the same time, the lead sulfate coating the plates acts as an insulator, reducing the battery’s performance. Charging reverses this process.
TPPL Battery Advantages
Compared to other lead-acid batteries, TPPL technology uses thinner, more pure lead plates. This increases the surface area exposed to the electrolyte solution, and increases the efficiency of the chemical reaction between the sulfur solution and lead plates.
At the same time, TPPL technology is a type of Absorbed Glass Mat (AGM) battery. Where other lead-acid battery technologies flood lead plates in a liquid electrolyte solution, TPPL and other AGM batteries use electrolyte-saturated fiberglass to store the electrolyte in a suspended state.
As the battery cycles through states of charge and discharge, the electrolyte is transferred from the fiberglass matting to the lead plates as needed. With the electrolyte contained in this way, gassing is minimized to the point that the batteries require zero watering.
These modifications allow TPPL batteries to reach higher current peaks, recharge more quickly, and need less maintenance than other lead acid batteries.
In most warehouse environments, TPPL technology can provide the forklift power facilities need to maintain near-continuous operations. That lead acid batteries offer the lowest cost of acquisition makes them a smart, economical choice, especially in facilities already equipped for lead acid.
Lead Acid Battery Challenges
Perhaps the greatest drawbacks to lead acid batteries come down to the underlying chemistry. They suffer from sulfation (the formation of lead sulfate crystals over the active material of the battery) that impedes a battery’s usable capacity, and ultimately decreases its cycle life.
Lead acid batteries require routine maintenance, and failure to adhere to a rather strict schedule can lower a battery’s lifespan. If the battery isn’t equalized — overcharged to essentially strip the buildup of lead sulfate from the active material — the lead sulfate crystals can harden on the lead plates, permanently reducing performance.
While lead acid batteries can be opportunity charged, and TPPL is better for it than other lead-acid batteries, there are strict limitations. Discharging a TPPL battery beyond 40% start of charge reduces cycle life, lowers capacity, and impedes the efficiency of the battery.
The basics of lithium ion batteries
While lead acid and lithium-ion batteries store charge and release electrons through a circuit, differences in their electrochemical processes give lithium-ion batteries higher energy densities and improved efficiency, among other benefits.
Lithium-ion Technology Components
Electrolyte solution. The electrolyte solution in a lithium-ion battery carries the lithium ions between the cathode and anode.
Anode. During discharge, the anode releases positively charged lithium ions into the electrolyte, and releases negatively charged electrons through the circuit of the device being powered. This is reversed during charging.
Separator. A separator sits between the anode and cathode. It allows the lithium ions to pass through, but denies the passage of electrons, creating a one-way path for the electrons through the circuit of the device.
Cathode. As the battery discharges, the cathode stores positive lithium ions from electrolyte solution, and receives electrons from the device’s circuit. This is reversed during charging.
Sensors and controls. Lithium-ion technologies include temperature sensors, voltage converters and regulator circuits, as well as monitors for the charge state.
Lithium-ion Battery Advantages
A battery's capacity depends on a number of factors, including manufacturers and models. But in general, lithium-ion batteries can store and discharge more energy in an equal amount of space as lead acid.
Lithium-ion doesn’t suffer from sulfation — the buildup of lead-sulfate crystals over the active material of a lead acid battery — that decreases the usable capacity of a lead acid battery, and causes lead batteries to need extra maintenance.
Lithium-ion batteries can be discharged to about 95% of their total capacity without a noticeable effect on their performance. They can last more than 3,000 throughput cycles — or nearly double the cycle life of a lead-acid battery
Lithium-ion Battery Challenges
While prices depend on the manufacturer and model, the upfront cost of lithium-ion batteries is generally higher than lead acid. If the increase in performance is more than a facility needs, they’ll find themselves paying for value they can’t realize. This is especially true for facilities already set up for lead acid, which may benefit more from upgrading to better lead-acid technologies.
While lithium-ion batteries require no regular maintenance from operators, they do still need to be inspected so that they can be serviced as-needed.
Compared to lead-acid batteries, which are almost 100% recyclable, only 5% of a lithium-ion battery is. Decommissioning these batteries has to be planned for.
Hydrogen Fuel Cells
The Basics Of Hydrogen Fuel Cells
Hydrogen fuel cells work by feeding the fuel (hydrogen) to the anode (negative electrode), where the hydrogen’s proton nucleus is separated from its electron. The electron moves through the device’s circuitry, creating the electricity to operate it. The proton moves through the electrolyte to the cathode (positive electrode), where it combines with oxygen from the air to produce water and heat.
The latest generation of motive power solutions hybridize fuel cell and lithium ion technologies. A relatively small lithium-ion battery in the fuel cell powers the equipment. The fuel cell recharges the battery while the equipment is in operation.
Hydrogen Fuel Cell Advantages
Hydrogen cells can be fully fueled in about five minutes, and provide absolute continuous power throughout their cycle even in extreme temperatures. Of the three technologies, hydrogen fuel provides the highest energy density. And they don’t suffer from the sag (the drop in voltage that happens as current is drawn) that all batteries see.
Hydrogen fuel cells operate better in extreme conditions than battery technologies, making them ideal for high throughput cold storage applications.
Hydrogen Fuel Cell Challenges
The acquisition cost and total cost of ownership of hydrogen fuel cells is high enough that not all facilities will realize a financial benefit from the efficiencies the technology brings. They are most practical in high throughput facilities running multiple shifts seven days a week.
While the fuel cells produce only heat, water, and electricity, how the fuel is sourced is still a challenge. The cheapest producers generate hydrogen from fossil fuels, and how environmentally friendly the fuel is depends on the producer’s process. “Green” hydrogen is produced using renewable sources, but is more expensive.
While the refueling stations for hydrogen cells make economical use of warehouse space, the infrastructure around the technology is more expensive and harder to find. While this issue is resolving itself as the technology becomes increasingly adopted, it’s still a consideration.
Before you commit, run a quantitative analysis.
Choosing the right motive power solution is critical for your operations. But with all of the options on the market today, how do you choose the right one for you?
The reality is that lead acid, lithium-ion, and hydrogen technologies can all power your lifts. Which will have the greatest return on your investment depends on your needs and processes, among other factors.
Before you commit to a forklift power solution, you’ll want to be sure a quantitative analysis is run that weighs the pros and cons of all the available solutions.
To help you find the right power package for your needs, Alta Motive Power has proprietary modeling software. Combined with a detailed analysis of your processes and power needs, we will find the best solution the industry has to offer.
Want to learn more about which motive power solution is right for your facility? Contact us to learn more.