How to choose the right lithium-ion forklift battery

A guide to safe, cost-effective and sustainable Li-ion lift truck power

The case for switching to lithium-ion (Li-ion) lift truck batteries is growing ever stronger. But what type of Li-ion battery will benefit your materials handling operation most? Mark Nicholson turns to Cat^® Lift Trucks for expert advice on the choices now available.

(Executive Summary)

Vladimir Bagioli from the organisation’s product management team is its leader on Li-ion battery power. “For forklift truck customers, the key issues to consider are the battery’s cost, lifespan, safety and environmental friendliness. There are several different Li-ion battery chemistries to choose from, each varying in relation to those factors.”

Today’s main choices of Li-ion battery chemistry are:

• Lithium iron phosphate (LFP)
• Nickel manganese cobalt oxide (NMC)
• Nickel cobalt aluminium oxide (NCA)
• Lithium titanate (LTO)

Weigh up the materials handling operational advantages

“We believe that lithium iron phosphate – LFP – offers the best balance of properties,” Vladimir advises. “Importantly, it has a higher thermal stability than its most popular competitor, NMC. This reduces the risk of thermal runaway.”

He continues: “LFP and NMC batteries both have long service lives – above 4,000 cycles. But the purchase cost for LFP is about 30% less than for NMC. LFP is also considered the most ecologically friendly Li-ion choice, as it has no need for cobalt and nickel. Those metals make batteries harder to recycle, and their quarrying can be damaging to the environment.”

NMC does score higher in terms of energy density. In other words, it stores more energy per unit weight or volume of battery. “This means that an NMC battery can be lighter and smaller. However, in the forklift world this isn’t usually a problem as we need heavy weights to counterbalance the loads lifted.”

For even greater energy density, nickel cobalt aluminium oxide – NCA – is an option. This is used mostly in the automotive industry, where weight reduction is a big priority. Lithium titanate – LTO – is particularly well suited to cold store applications. It has a lower energy density than the others but offers exceptional cycle life and safety. “In the immediate future, LTO’s much higher cost makes it a less likely choice,” Vladimir notes.

Don’t compromise on forklift battery safety

“Readers will undoubtedly have seen reports of electric scooter, bike or car batteries catching fire,” says Vladimir. “Despite the sensational stories, this is relatively rare and is easy to prevent.”

He warns customers, first of all, to avoid using cheap, poor-quality batteries. “High quality in the design and manufacture of Li-ion batteries enhances their safety.”

Next, he recommends lithium iron phosphate (LFP) batteries, for their higher thermal stability. “Thermal runaway is much less likely with these and it’s much less severe if it happens.”

In tests, LFP batteries remain stable until temperatures reach 230°C. By contrast, NMC batteries can begin thermal runaway from 160°C. NMC runaways emit more heat and reach temperatures of 800°C. LFP will only heat up to 620°C. In addition, LFP runaways take longer to develop. This gives workers and managers more time to act, after an initial fault warning. In addition, the ejections in an NMC fire are more hazardous as they include incandescent metal particles.

See the new generation of safe Li-ion lift truck batteries

For extra confidence, Cat Lift Trucks now brings customers a new generation of LFP Li-ion batteries. These have been produced by trusted partners in its global materials handling family. The R&D teams who develop Cat^® lift trucks have collaborated in the batteries’ design and testing. Their aim has been to meet forklift users’ specific needs and to maximise all the advantages of Li-ion technology.

“As an extra safety measure, each battery has an inbuilt fire extinguisher,” Vladimir adds. “This is designed to contain any lithium fire and bring down the temperature.”

The batteries are protected by a thick metal cover, which provides physical strength and prevents water and dust ingress to IP54 standard. These defences guard against external factors which can damage batteries and make them vulnerable to thermal runaway.

An advanced battery management system (BMS) also provides important safeguards. It monitors the Li-ion battery and protects against hazardous conditions including overload, short circuit, deep discharge and overcharge.

Vladimir concludes: “Along with safety assurance, our new Li-ion batteries promise a low total cost of operation, minimal battery-related downtime and a reduced carbon footprint. Their runtime is impressive even in cold conditions, as we’ve included an inbuilt heater to optimise charging temperature. And you can be certain of a long service life, as each comes with a five-year guarantee.”