New Forklift Battery Technology: Lithium-ion vs Lead-Acid Batteries

Over the years, forklifts have evolved from basic diesel engine machines to advanced, electric forklifts that are quieter, safer and easier to operate. But the changes haven’t stopped there, major forklift brands across the globe have worked to improve the efficiency of their machines. One of the most innovative changes that have been made in the last few years is the change from lead-acid batteries to Lithium-ion (li-ion).

Li-ion History

Li-ion batteries aren’t a new invention, phones and other small electronics have been using them since the 1980’s. However, due to issues like catching fire if accidentally overcharged, Li-ion batteries haven’t really made it to the market for larger products and machinery. Until now. 

In the late 90’s a new way of creating Li-ion batteries was found, reducing the chance of combustion and increasing safety. Now, major forklift brands are making the change from lead-acid to Li-ion due to their superior performance and reduced costs over their lifetime. 

Benefits of Li-ion Batteries

It’s common knowledge that electric forklifts have a higher upfront cost than LPG or diesel versions, and Li-ion increases this upfront cost yet again. However, this is one of the only flaws that Li-ion has and the higher upfront cost is more than made up for when you factor in replacement and maintenance costs of lead-acid batteries. 

According to Kalmar, this new forklift battery technology is able to last for “2,400-4,000 cycles” compared to lead-acid batteries which only last “1,200-1,400”. Along with this, Li-ion batteries also charge quicker, with 1 minute being enough to charge about 1% of the battery. Meaning 100 minutes is enough to get a completely flat battery back up to full operational capacity. 

Credit: Kalmar Electric Forklifts

This improved charging time makes Li-ion batteries a great investment for companies that operate multiple shifts throughout the day, or businesses that run 24/7. The short 1 minute = 1% charging time means you can partially recharge Li-ion electric forklifts very quickly between shifts. Letting you use them multiple times in a single day without worry. Lead-acid batteries on the other hand take around 8 hours to charge, meaning you’ll need multiple batteries if you want to operate a single forklift across multiple shifts without stopping. 

One of the reasons Li-ion batteries can operate for so long without stopping is the lack of ‘voltage sag’. Conventional lead-acid batteries suffer from reduced performance as the battery drains. Many electric forklifts run at 12.8 volts, and if the voltage drops below 12v (which is often the case once the battery charge falls below 35%), then some electronics may stop working and the lights may dim. This is commonly referred to as ‘voltage sag’. But Li-ion electric forklifts will generally not suffer from this, as Li-ion batteries will output almost the exact same voltage right up until they go flat. 

“The discharge curve of lithium batteries (especially relative to lead acid) is essentially flat – meaning that a 20% charged battery will be providing nearly the same output voltage as an 80% charged battery. This prevents any issues caused by the “voltage sag” common to lead acid as they discharge.”

—PowerTech Systems

Increased Working Space

There are also some physical benefits to this new forklift battery technology as well. Li-ion batteries are about a third of the weight of a lead-acid battery, making them substantially easier to move around and replace when necessary. Of course, this is made less of an issue as you don’t need to remove Li-ion batteries from the forklift to be charge them. As long as you can park your forklift near your charging outlet, you can simply plug it in to charge. This brings savings in a different way, as you’ll no longer need a dedicated charging space for batteries that is well ventilated and out of the way. 

Another aspect of lead-acid batteries that can affect the working space in your business is their maintenance. While Li-ion batteries are basically maintenance-free, lead-acid batteries require regular maintenance to keep them functioning properly. This not only increases labour costs and downtime, it also takes up space. Forklifts will need to be out of the way of your working fleet, but still in an area with enough space to safely provide the maintenance they need. 

Credit: Kalmar Electric Forklifts

Of course, Li-ion batteries don’t suit every business. While they are definitely a superior choice for multi-shift businesses operating multiple forklifts around the clock, smaller businesses with a single operator may find it more cost-effective to simply have a single lead-acid forklift instead. While space may play a role, the smaller upfront cost may be worth it if there’s not going to be any noticeable difference in purchasing a Li-ion forklift. Lead-acid batteries are also at an advantage when it comes to some counterbalance forklifts, as they weigh more by default, the batteries are often enough to act as a counterweight themselves. Li-ion batteries are much lighter and you’ll need to compensate for this difference with additional weights. 

What to Consider When Choosing an Electric Forklift

As with most decisions about the machinery in your business, there will be a number of factors you will need to consider when choosing between a lead-acid or Lithium-ion battery forklift. The top 5 things to consider are: 

1. Price
2. Charging time & space
3. Maintenance costs & space
4. Size of your fleet
5. Number of operators & shifts per day

Once you understand where your budget is, the amount of dedicated space and time you’re willing to spend and the number of forklifts and operators you’ll need, you’ll find it easier to decide whether lead-acid or Li-ion is right for you. 

Of course, forklift battery technology is always changing and undoubtedly there will be a new type of battery in a few years. In fact, there already is a new type called ‘super capacitor batteries’ that have an even higher density and operational cycle than Li-ion. However, the cost of materials and construction for these batteries makes them incredibly expensive. So for the time being, Li-ion and lead-acid batteries are the best choices when it comes to electric forklifts.