October 27, 2021
Selecting the proper battery technology for your electric forklift is a critical decision. Whether you are upgrading an existing battery, or purchasing a new forklift, you need to thoroughly assess battery options as it can have a direct impact on the forklift performance, business productivity, and bottom line.
There are predominantly two types of battery technologies powering commercial forklifts - Lead-acid and Lithium-ion. In this guide we will compare them on different parameters like- technology, costs, maintenance, and charging needs, to help you reach an informed decision. Before getting into a detailed comparison, let’s briefly look at the working of these two technologies and tips on battery sizing.
Lead-acid Batteries
A lead acid battery consists of lead plates as electrodes, immersed in an electrolytic solution of sulfuric acid and water. Electricity is generated by a chemical reaction between lead and sulphuric acid. Water gets lost during the chemical reaction so regular refilling of water in the battery is necessary to maintain the required level.
Lithium-ion Batteries
There are multiple types of lithium ion batteries are available in the market depending on the type of cathode material used in them. Some of the lithium-ion battery options include lithium cobalt oxide, lithium manganese oxide and, lithium iron phosphate (LFP), of which LFP is one of the most popular chemistries in the modern material handling industry. LFP offers higher safety, and current and has a lower environmental impact as compared to some other types of lithium-ion batteries.
Selecting the right battery size is critical to ensure that your forklift can perform at its peak and lift the load it is rated to lift. There are three parts of battery sizing that you need to look at-
1.Battery Voltage & Ampere Hour
Forklift batteries are typically available in four voltage options and selecting the right one is the most important part of battery sizing. An oversized battery may cause severe, and irreversible damage to the truck so be sure to know what kind of voltages your truck can handle. Generally, the voltage is marked on the spec plate of most forklifts.
It is advised to choose a battery with the highest ampere-hour for the approved voltage rating to get maximum power for your forklift.
While the table below gives you an overview about which battery voltage is suited for which equipment type, be sure to speak with your local battery specialist to understand what battery size is appropriate for your forklift.
Voltages Type of Forklift 24-Volt / 36-Volt batteries Rider ForkliftsVoltages Type of Forklift 24-Volt / 36-Volt batteries Rider ForkliftsStackersPallet JacksOrder PickersNarrow Aisle Forklift 48-Volt / 80 Volt Batteries Reach TrucksCounterbalanced Electric Forklifts 120 Volt Batteries and above Yard VehiclesShunt Trucks
2.Battery Dimensions
Next, you need to measure the forklift’s battery compartment size and make sure that the battery fits in well. The battery needs to fit the compartment properly. A battery that is too big, or too small could pose a safety hazard.
3.Battery Weight
Check the spec sheet or spec plate to find out the Minimum and Maximum battery weight requirements for the truck. If you pick a battery which is heavier than the maximum weight then you run a risk of putting unnecessary strain on various equipment parts, even voiding the manufacturer's warranty. In many cases, battery also acts as a counterbalance for your truck. A battery lighter than the minimum required weight may reduce your trucks lifting capacity and cause safety issues. When changing the battery on any forklift, a new spec plate may be required to outline the altered capacity of the machine based on any weight change. The battery of an electric forklift acts as a counterweight to the machine and is critical to its lift capacity.
In the next part, we will look at a detailed comparison of the lead-acid and lithium-ion technologies on various vital parameters.
Lead-acid batteries:
If you operate your business for 16 or 24 hours a day, battery charging times become crucial to ensure smooth running of your operations since a typical battery discharges in about 6-8 hours. A lead acid battery needs about 8 hours to charge followed by 8 hours of cooling period, making it a total of 16 hours before it can be used again. So, for a multi-shift operation, you may need 2-3 lead-acid batteries per forklift. If you do not carry multiple batteries for each forklift, you may experience downtimes due to unavailability of equipment, directly impacting the bottom line.
Lithium-ion batteries
A lithium-ion battery gets fully charged in less than 2 hours and does not require a cooling off period like lead-acid batteries. Li-ion batteries can also be charged in 15-30 minutes spurts, often known as opportunity charging, making it possible to charge them during lunch breaks or anytime the forklift is idle for a few minutes. You to carry out multi-shift operations with just one battery per forklift, thanks to increased fleet availability because of fast charging.
Bottom line
While there is a huge difference in the charging times, both types of batteries usually last the same number of hours (between 6-8) after the full charge. If you have a single-shift operation and a small fleet size, you can make it work with lead acid-batteries. As your fleet size and operations grow, lithium-ion batteries become unavoidable to carry-on uninterrupted operations.
Speak with one of our specialists to get battery recommendations based on your operations.
Lead-acid batteries
Since you may need to carry multiple lead-acid batteries per forklift, you also need to account for additional storage space for them. Additionally, you must ensure a safe storage environment- one which is away from hot air ducts and other heat sources, does not get direct sunlight, and is maintained at room temperature or lower.
You also need to follow a safe charging process for lead-acid batteries and allocate resources for the same. For every charge, the battery must be removed from the forklift and placed on the designated charging rack, making it a labor intensive process. Because the battery is heavy, it may require trained personnel to use a lifting equipment for moving it from forklift to charging rack and vice-a-versa.
That said, most of the facilities today are equipped with electrical supply infrastructure suitable for the lead acid batteries. You may not need to make any significant investments towards the battery charges, outlets, and cabling.
Lithium-ion batteries
You don’t need the additional storage infrastructure while opting for lithium-ion batteries as you don’t need multiple batteries per forklift. Even while charging, you can let the battery sit inside the forklift itself, making the process simple and cost-effective. You can simply connect the battery to a charger by driving your forklift to a power outlet.
Since Li-ion battery charging is much faster, they also need higher input current for the same. You may need to conduct an energy audit of your facility to understand if you need to revamp your electrical infrastructure for efficient charging of Li-ion batteries. It will be a one time cost of adopting the Li-ion batteries for powering your forklifts.
Bottom line
Lithium ion batteries can help you save valuable space, and time of your people owing to its faster and simpler charging process. If you plan to purchase lead-acid batteries, you should account for these additional, and often hidden, infrastructure costs.
On the other hand, you may need to upgrade your electrical infrastructure for adopting Li-ion batteries as their chargers usually need higher input current.
Lead-acid batteries
If not maintained properly, lead-acid batteries undergo a chemical process called battery sulfation, which can cause them to break down. To avoid this, it is important to maintain the lever of water in the electrolyte. Topping up the battery with distilled water at regular intervals is essential to maintaining the health of a lead-acid battery.
Watering the batteries for a large fleet can be a tedious and costly process. You need to allocate trained personnel to undertake this procedure and ensure that they follow the safety protocol while doing so.
Lithium-ion batteries
Lithium-ion batteries are much easier to maintain as they do not need to be topped with water and does not require any such frequent maintenance procedures.
Bottom line
Regular watering of lead-acid batteries is inevitable to maintain their output, something which you don’t need to do with lithium-ion batteries. Tedious and cost-intensive maintenance procedure is one of the major drawbacks of lead-acid batteries.
Lead-acid batteries
Since the lead-acid batteries are made up of two high-risk chemicals- sulphuric acid and lead, they could pose a safety hazard for you and your team. There is a risk of sulphuric acid contacting skin, and eyes of those performing the maintenance procedure so you need to ensure wearing of personal protective equipment (PPE) like splash-proof goggles, acid resistant apron, face-shield, and rubber gloves.
Lead-acid batteries may also produce an explosive mix of hydrogen (H2) and oxygen (O2) gases while being charged. If the charging room is not ventilated appropriately, there is a risk of explosion. Among other measures, you need to install hydrogen sensors at the ceiling of the rooms where lead-acid batteries are charged.
Over-charging vented lead-acid batteries, especially old ones, can produce a highly toxic fume called hydrogen sulfide (H2S). If such an event occurs, you may need to evacuate the area to ensure no one is exposed to this dangerous gas.
Lithium-ion batteries
Lithium-ion batteries are considered much safer as compared to lead-acid batteries since they do not pose as many health hazards for those working with them. These batteries are completely sealed and do not have to be opened for watering, reducing the danger of electrolyte spills, toxic fumes, or sulphation as in the case of lead-acid batteries.
Bottom line
Lithium-ion batteries can be considered much safer than the lead-acid batteries. Health and safety are paramount in any work environment, and you need to account for costs associated with training, labor, and infrastructure to create a safe environment when using lead-acid batteries.
Lead-acid batteries
A well-maintained lead acid battery has a lifespan of 1000 to 1500 charging cycles. Important point to note here is that even if you charge a lead-acid battery for a short period, say 15 minutes, that counts as one charging cycle. This further reduces the lifespan of a lead-acid battery if you do not carefully charge it to 100% every time.
In addition to maintenance, the timing of charging can also affect a lead-acid battery’s lifespan. You should not leave a lead-acid battery in a state of partial discharge and need to immediately charge them to ensure their performance and longevity.
Lithium-ion batteries
A Li-ion battery lasts anywhere in between 2,000 to 3,000 charging cycles. Unlike lead-acid battery, lithium-ion is considered to have gone through one charging cycle only when it gets 100% charged. Intermittent charging of a few minutes adds to the convenience but does not reduce the lifespan of a li-ion battery.
Also, leaving a li-ion battery in a state of partial discharge does not negatively affect their lifespan as they don’t suffer any damage.
Bottom line
The overall lifespan of the batteries you chose determines how often you will need to replace them. Li-ion batteries can help you save on the recurring replacement cost considering they have almost double the cycle life as compared to lead-acid batteries.
Lead-acid Batteries
Lead-acid batteries bleed energy while charging, discharging and even while sitting idle. As a result, only about 80% of the energy used for charging the battery is actually available as the output, making lead-acid batteries energy inefficient and bringing up the electricity costs.
Lithium-ion batteries
Lithium-ion batteries can be considered much more energy efficient as the losses are minimal and most of the energy used for charging is available as output, as much as 99% in some cases.
Bottom line
Lithium-ion batteries can help you reduce electricity costs as they provide more output owing to minimal energy losses. You can expect savings up to 30% as compared to lead-acid batteries which are notorious for bleeding energy.
Lead-acid Batteries
The upfront cost of a lead acid battery is quite low as compared to other types of batteries.
Lithium-ion Batteries
Initial investment for a li-ion battery may be almost twice as much as that for a lead-acid battery.
Bottom line
Owing to the low upfront cost, lead-acid batteries may be a suitable option in certain business scenarios as mentioned in the point #1. Looking at the Total Cost of Ownership (TCO) is critical as it gives a holistic and long term picture when making such investments.
Let’s compare TCO for these two types of batteries for a typical two shift operation.
Parameter Lead-acid batteries Lithium-ion batteries Initial cost 2 batteries (One battery/shift) 1 battery MaintenanceParameter Lead-acid batteries Lithium-ion batteries Initial cost 2 batteries (One battery/shift) 1 battery Maintenancecost Related to watering and, battery swapping per shift Not required Electricity for charging Higher cost as they bleed energy and usable output is much lesserthan the input Up to 30% savings due to higher energy efficiency - provides upto 95-99% of energy stored as output batteryreplacement Cost Every 1500 charging cycles1 cycle= every time it is plugged in even if it is justfor a 15 minute coffee break May extend up to 3,000 charging cycles1 cycle= 100% charge Total Cost of ownership $$$ $$
Purchasing batteries for your fleet is a major investment decision, one which you should make considering various parameters that we have documented in this guide. Having compared the two popular battery technologies on the critical parameters, it is safe to conclude that even-though lead-acid battery technology is the oldest one, it may not be the best option for your material handling needs.
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You can refer the following table for a quick comparison of the two most popular battery technologies.
Following table summarizes the comparison between lead-acid and lithium-ion batteries for your quick reference.
Parameter Lead-acid batteries Lithium-ion batteries No. of shifts with one battery 1 Up-to 3 Charging time 8 hours 2-3 hours Opportunity charging Possible, however battery life reduces drastically Charging for as low as 5-10 minutes whenever possible Safety & Health Risks High Low Watering the battery Yes N/A Maintenance Cost High Low Battery LifeSpan ~1500 cycles 2000 - 3000 cycles Electrical Infrastructure Use existing May need Upgrade Replacement cost High Low Energy Efficiency Low High Electricity Cost High lower Save up to 30% because of higher energy efficiency Upfront Cost Low High Total Cost of Ownership High Low Environment Friendly No YesParameter Lead-acid batteries Lithium-ion batteries No. of shifts with one battery 1 Up-to 3 Charging time 8 hours 2-3 hours Opportunity charging Possible, however battery life reduces drastically Charging for as low as 5-10 minutes whenever possible Safety & Health Risks High Low Watering the battery Yes N/A Maintenance Cost High Low Battery LifeSpan ~1500 cycles 2000 - 3000 cycles Electrical Infrastructure Use existing May need Upgrade Replacement cost High Low Energy Efficiency Low High Electricity Cost High lower Save up to 30% because of higher energy efficiency Upfront Cost Low High Total Cost of Ownership High Low Environment Friendly No Yes
Williams Machinery offers complete material handling solutions. Our specialists can help you select the right forklift and battery for your business needs.
Did you know the very first commercial lithium-ion battery was used in 1991?
However, when it comes to forklifts lithium-ion batteries have only been around for 12 years.
Lead acid is the ole reliable, dating all the way back to the early 1920s.
While they are older than you, lead acid batteries have had loads of updates over the years and are still a very sound option for certain applications, as you’ll see below.
So let’s get right to it…
Lead-Acid forklift batteries are rechargeable batteries that have a high power-to-weight ratio and are sought after due to their lower cost.
They are known as motive batteries, AKA the motor of the vehicle.
What most people don’t think of is the sheer size and weight of lead-acid batteries.
The common car battery weighs about 40 lbs on average but a forklift battery can be between 800 to 4,000 lbs.
In total a forklift weighs 9,000 lbs on average. That is the equivalent of 5 average-sized buffalo.
Despite this, one of the benefits of the lead-acid battery is actually its weight.
Forklifts lift heavy objects (sometimes as much as 36,000 lbs.) hundreds of feet high, so they need something to help balance the weight.
In this case, the battery acts as a counterbalance and keeps the forklift from tipping over when lifting heavy loads.
Lithium-Ion forklift batteries are rechargeable lithium and graphite batteries with a very high energy density, low discharge rate and no memory loss.
While lithium is a much lighter material, these batteries still require either a bodybuilder or a machine to move, weighing between 500 to 2,500 lbs.
This lighter battery means less weight that your forklift is carrying, so sometimes you’ll even see a metal plate to help provide additional weight to keep the forklift from tilting when carrying heavy loads.
There are some pros and cons to each of these battery types, but we’ll look at the major areas to help you come to a conclusion on which is best for your application.
In this 4 round heavy-weight fight we will look at maintenance, charging, energy usage and most important, upfront cost.
Let’s have a clean and fair fight, Round one…. take it away Bruce Buffer!
To keep it short and simple — lead-acid batteries require more maintenance.
Now the longer version is that lead-acid batteries require watering.
Just like taking care of your garden you gotta do the same with these batteries.
What happens is water fills the individual cells in your battery to provide a functional level of chemicals and electrolytes that will produce power.
Doesn’t sound too bad right?
Wrong!
Even if you run a one-shift application your batteries will probably need watered once a week or at the very least bi-weekly. And this requires special equipment and the right level of care, because you water too much or too little and you’ll damage your battery.
So typically this labor will be performed by a material handling company/forklift dealer at an hourly rate.
Other maintenance steps to take are:
Almost none. Lithium-ion batteries save you thousands because they do not require the most expensive maintenance piece… watering.
However, there are a few things you should make sure to check on every so often. These are listed below.
Round 1 Winner: Lithium-Ion
If you take great care of your battery you will get about 1,500 charge cycles. Let me repeat that… GREAT CARE.
This equates to about 5 years if you charge the battery once per day.
Of course, this is the over optimistic side because who doesn’t appreciate a half glass full person in your corner?
But, if we are going to be more realistic, you should expect about 3.5 years of life.
That isn’t too bad, but the problem arises when you have a 2 or 3-shift application.
In these cases you will need at least two batteries per truck because charge time will take 8 hours and then you will need a cool down time of 8 hours as well.
You can get a better picture in the chart below.
LEAD-ACIDLITHIUM-IONUse Time8 Hours8 HoursCharge Time8 Hours1-4 HoursCool Time8 Hours0 HoursTotal Time Needed Before Use16 Hours1-4 HoursLEAD-ACIDLITHIUM-IONUse Time8 Hours8 HoursCharge Time8 Hours1-4 HoursCool Time8 Hours0 HoursTotal Time Needed Before Use16 Hours1-4 Hours
As you can see above lithium-ion can be 4-16x more effective when it comes to charging production.
But, what about degradation?
You can put a checkmark next to lithium-ion on this one as well.
Lithium-ion batteries generally last about 2,000 – 3,000 cycles. Which is almost double of what you can expect with a lead-acid battery.
This point goes to lithium-ion.
Round 2 Winner: Lithium-Ion
Wouldn’t you like to save money on your monthly electric bill?
Well that’s what we’re looking at here, finding the battery that is more efficient *cough, cough* cheaper on utilities.
According to the always trustworthy Wikipedia, the energy density of a lead acid battery is 80-90 Wh/L with a specific energy of 35-40 Wh/kg.
All that seems confusing, but all it means is the measure of how much energy is stored in the battery.
Another fun fact for you, lead-acid batteries are not good at keeping their energy. They lose amps while moving, charging, lifting and idling.
Meaning, as a shift carries on the forklift will become weaker and weaker as the battery level goes down, so you might be able to lift 3,500 lbs 186″ at the beginning of a shift but at hour 4 you might only be able to lift 2,600 lbs 186″.
The energy density of a lithium-ion battery is 100-265 Wh/kg.
That is 3-6 times stronger than lead-acid.
The other big kicker here, lithium-ion batteries keep a constant voltage level during their discharge cycle. This can equal 50% savings in energy compared to lead-acid.
One final point to add is that charging a lithium-ion battery can be done without removing the battery from the forklift.
Unlike the lead-acid batteries, lithium-ion gives users the chance to use opportunity charging between shifts or even during break time.
This is a huge advantage because now you do not need a second battery and your charging space will be just that, a charging space.
Typically with lead-acid you will need a space dedicated for storing your extra batteries while they charge.
This is a major advantage because now you can take that dedicated charging space and restructure it to be additional storage space.
Round 3 Winner: Lithium-Ion
Lead-acid batteries will cost you about $5,000-12,000 brand new depending on your size and specs.
The articles below are detailed on electric forklifts (class 1), reach trucks and order pickers (class 2) and pallet jacks, pallet stackers and tow tractors (class 3) and go into a little further detail on the battery costs for each model type. I wrote them so I promise you they aren’t too awful.
On average you can expect to spend $17,000-25,000 on a lithium-ion forklift battery.
Now, before you completely write of lithium, consider the added perks from above and make sure to look at the final conclusion below.
Round 4 Winner: Lead-Acid
The easy answer is lithium-ion is the better, more reliable, more efficient, and bigger bang for your buck option.
However, this is only an obvious choice if you are running a 2-3 shift application with a few forklifts.
If you have a warehouse with only a couple of forklifts and pallet jacks that are not used around the clock then you may be better off using lead-acid.
Lithium-ion batteries take the W when it comes to maintenance, charge rate, charging capacity, degradation, lifespan, safety and overall ROI. However, lead-acid batteries are much cheaper and if they are only used intermittently, then they are probably the better option for you.
The best time to water your batteries is right before a shift, after the batteries have had time to cool down.
Lead-acid batteries will last 1,500 charging hours if maintained well. Lithium-ion batteries will last 2,000 to 3,000 charging hours.
Yes, propane forklifts have batteries. However, unlike electric forklifts the purpose of the battery on propane forklifts is not to produce power, it is to help start the forklift.
A forklift battery weighs between 800 to 4,000 lbs. depending on the type (lithium-ion vs lead-acid) and size (24V, 36V, 48V).