Lead-Acid batteries have been around for about 140 years but now they have got strong competition from modern Li-ion technology. Both traditional lead-acid and lithium-ion (Li-ion) batteries are used to power forklift trucks in materials handling operations. Nowadays, our Cat® electric forklifts and warehouse equipment come also with Li-ion batteries.
But what are the advantages of lithium-ion batteries? Do their benefits push efficiency and productivity to even higher levels than our electric forklifts achieve already? Here’s a look at what these batteries have to offer.
“Lithium batteries” is a common name for the cell type used in many of the things that surround us such as mobile devices, electric cars and forklift trucks. They are everywhere. Since the requirements are very different depending on application, there are also many types of lithium-ion batteries. Things like performance, durability, life cycle time and cost depend on which cell chemistry and cell type is used. Prices for the various cell types are very different and normally you can expect to get what you pay for.
Cat lift trucks use High Performance Prismatic NMC cells, known as Li-Pro, enabling trucks to be used in most applications, including demanding heavy duty and shift operations. Li-Pro offers outstanding performance and reliability over a very long time, providing cost savings and fast return on investment, ROI.
Cat forklift trucks offer specially developed Li-ion batteries to provide maximum safety and integration, while maintaining the proven high quality and reliability of Cat lift trucks. The battery cells are controlled by a surveillance and monitoring system called Battery Management System, or BMS, which controls everything that is going on. The BMS measures the health, temperature, charging, discharging activities of cells and logs all data.
The BMS communicates with the truck via CAN (Controller Area Network) and sends information about the battery status, such as discharge level, which is visible on the standard truck display. In case of any problems, error codes will be displayed and in a worst-case scenario, the battery will automatically shut down the truck in a safe way. Even the charger is communicating with the BMS via CAN, achieving the best and fastest charging possible, depending on the battery status. Cat® Lift Trucks offer a wide range of fully integrated, tested, and approved lithium batteries to provide maximum safety, performance and reliability.
EASE OF USE
A major advantage of lithium-ion batteries is that they are designed specifically with ease of use in mind, not least ease of charging. They can simply be plugged in whenever possible, even if it is only for a few minutes. Opportunity charging provides the ability to plug the charger directly into a Li-ion battery so it can be charged at any time of the day. With the correct specification of Li-ion forklift battery and charger combination to the application, charging during normal breaks in a shift are enough to manage constant 24/7 operation. The lithium batteries on the Cat forklifts can be fully charged in an hour (1C charging) and in addition, due to the CAN integration with the charger, any available Li-ion charger can be used, as long as the voltage is the same or higher than the battery voltage. The charger will automatically adapt to the battery and provide correct voltage and current. Very smart.
Li-Pro forklift batteries offered by Cat Lift Trucks have a very long life-span. Since Li-ion batteries are a modern technology, they are not sensitive to charging as they like being charged. These high performance Li-Pro batteries have a life span of about 5000 capacity cycles. This is a different way of measuring compared to the about 1500 charging cycles for traditional lead-acid batteries. In most applications you will need three to four lead-acid batteries providing the same lifetime as one Li-ion battery. Additionally, unlike Li-ion, the service life of traditional batteries can be impacted on by their use and maintenance – miss filling with water, not being properly cleaned and charging or equalizing a lead-acid battery will reduce its life-span drastically. If this becomes a big problem, then Li-ion batteries are the solution.
Because of the very high quality and performance of the Li-Pro batteries in the Cat forklifts, they come with a very generous and extensive 5-year warranty, making sure the battery delivers what is promised.
BATTERY RUN TIME
Another advantage of lithium-ion batteries is that they offer a constant high-power supply which does not decline as the battery discharges. The truck will run with the same performance regardless of what the State of Charge (SOC) level is. During everyday materials handling activities, electric forklifts powered by lithium-ion batteries will typically need charging for about one hour per shift to run in constant operation. Charging can be done at any point in time and when convenient. The intelligent built-in BMS will warn the driver when the charge level is low. Lead-acid batteries normally need 7-10 hours charging with no interruption depending on the charger and for shift operation a battery change system is the only possible solution, which requires investment, space and is laboursome with frequent battery changes. When adding up this cost over time, Li-ion batteries from Cat Lift Trucks are a very good investment.
Practically maintenance-free, this is another big advantage of lithium-ion batteries, reducing labour costs and improving productivity. It’s not just the charging routines that make a difference, there are also a number of other tasks to be considered with lead-acid batteries like watering (topping up the battery’s fluid levels with distilled water to avoid damage to the battery, keeping them clean to limit current leakage between cells, rinsing poles from oxidation etc.)
This weekly and rather unpleasant work is required to keep the battery healthy. Lead-acid batteries are very labour intensive and if not properly maintained, lifetime is drastically reduced. This is not the case with Li-ion forklift batteries, which do not require any daily maintenance, other than checking the cables and connectors and wiping the dust. There are no fluids to add. The advanced built-in BMS in lithium-ion batteries automatically performs cell balancing when they are charged to 100%. This is not noticeable in normal applications as full balancing is done whenever there is enough time for it to be completed.
Saving both time and money, lithium-ion batteries are much more energy efficient. They pack tremendous energy into a small space and deliver sustained performance over long run-times. Lead-acid batteries are bulky, although they are great at supplying current for electric forklift trucks carrying out their duties. Lead-acid energy costs are higher, as they need regular overcharging in the gassing phase to stay healthy. With no gassing process, very low thermal losses and intelligent charging technology, the amount of draw from the grid is up to 30% less with lithium-ion batteries, while storing the same amount of useful energy in the battery. This energy efficiency is not only saving money, but also our environment.
Lead-acid batteries produce explosive H2 gas when being charged, which needs to be evacuated. This means they need a specific charging room with air evacuation also including safety features such as eye wash, gloves, eye protection and of course a fire extinguisher. Charging lead acid batteries is rather costly, evacuating already heated air and the cost of square meters, which could be used for other purposes, may influence which battery type you choose.
COSTS AND TOTAL COST OF OWNERSHIP (TCO)
Currently, lead-acid batteries need to be considered as a commodity as their life time is usually much shorter than the trucks. For Li-Pro Li-ion batteries it´s a different story. Their total cost of ownership is lower due to their much longer life span and other factors such as: less money spent on energy for charging; less labour (workers do not need to swap out or change batteries); less time and labour spent on maintenance (such as watering lead acid batteries) and overall, less energy wasted because, as we already mentioned, Li-ion batteries consume up to 30 % less energy from the grid. Return of Investment, ROI, is usually very fast, typically 2-4 years depending on application. Clean batteries and an improved working environment come as a bonus.
GRID SUPPLY AND LOAD MANAGEMENT
Because lithium-ion batteries usually require large chargers to accommodate fast charging, power supply may be challenging. For this reason, a Load Management system is available. When charging multiple trucks at the same time, current draw might exceed available power from the grid. To avoid that, Load Management automatically controls the chargers, providing most energy to the battery with lowest state of charge. This will not only enable continuous forklift operation, but also it keeps grid costs to a minimum.
SAFETY AND WORKER SATISFACTION
Li-ion forklift batteries require less handling and so could be a safer option as they are very stable. The cells are completely sealed so there is no corrosion, sulfation, acid spills or contamination to worry about – which is much better for the environment as well. The battery is smart, meaning it´s constantly controlled by the BMS to secure safe operation and will shut the truck down if any problems occur.
Therefore, it is easy to see that there are many advantages of using lithium-ion batteries in electric forklift trucks. However, when considering Li-ion batteries, it is also worth noting the few disadvantages. High performance Li-Pro batteries are a bigger initial investment than traditional batteries, however, with a proper ROI calculation at hand, the Total Cost of Operation (TCO) is, in most cases, proven to be lower.
The main challenges we are faced with is providing enough power supply to feed Li-ion batteries because the chargers are bigger. To reduce driving distances and time consumption, chargers are preferably positioned close to where operators take their breaks.
Finally, the majority of lead-acid batteries are recycled and have value when they reach end of life. lithium-ion batteries are more difficult and costly to recycle, However, the long lifetime of lithium-ion batteries and the possibility to use them in stationary applications when they are no longer suitable for forklift applications means environmental impact is low.
All lithium-ion batteries supplied with Cat forklifts and warehouse equipment are conveniently reused and recycled after forklift applications at no extra cost.
Ultimately, deciding on the right type of battery to use in your electric forklift trucks is up to you and will depend upon many factors such as your set up and the materials handling tasks you need your forklifts to perform.
For more information on battery types and what’s available, visit our information on electric forklift trucks or our blog section which has other articles on this topic.