Overview

In the battery power market today there is a myriad of available battery types to choose from. It’s a critical decision which not only impacts how well the product will operate but also how safely it can operate. Factors such as how much power is required, the time required to charge, operating temperatures, operating environment, packaging dimensions, and weight are all examples of key parameters that must be considered.

The Material Handling / Motive Power battery market requires some of the highest power products in the world so safety is a key parameter and necessity.

Safety by Design

The Green Cubes Technology engineering team has extensive experience in working with various battery technologies. This wealth of experience and knowledge of the various available battery technologies was used in selecting the optimal chemistry for the material handling market. By selecting Lithium Iron Phosphate (LFP) for the Lithium SafeFlex MH batteries the team utilized a lithium chemistry that is first and foremost known for its inherent safety.

Chemical structure

While higher energy lithium chemistries are available, LFP was selected due to its stable chemical make-up. The Phosphate & Oxygen bond is both thermally and chemically stable due to the single-dimensional lattice structure. Its 1 D lattice structure limits how lithium ions are transferred. This transference limitation enables improved stability and cycle life. A demonstration of how much more stable the LFP chemistry is compared to the longer established high energy Lithium Cobalt Oxide (LCO), i.e. the lithium battery used in consumer electronics, is to compare the thermal runaway temperatures, which are the high temperatures at which the chemistries begin to become unstable and volatile. LCO has a much lower thermal runaway temperature of 150°C (302°F) compared to LFP’s thermal runaway temperature of 270°C (518°F). This large difference shows LFP to be the much safer of the two lithium chemistries.

In addition to chemistry selection, the physical construction is an important parameter to consider in the design selection process. All lithium batteries contain a critical component called the separator, which is placed in between the anode and cathode layers in the electrode. The separator limits the chemical reaction of the electrode and helps to prevent thermal runaways by closing its porous structure at high temperatures. The Green Cubes team has selected cells which incorporate ceramic separators. The ceramic material is resilient at high temperatures and helps prevent the breakdown of the separator that occurs during a thermal runaway event.

Safety by Product Experience

Over the past 20 years, Green Cubes Technology has designed and produced millions of lithium battery systems along with other chemistries such as NiMH, NiCd, and lead acid. Green Cubes has lifesaving batteries integrated in Lexus vehicles, mines, hospitals, and a multitude of other industrial and rough environment applications. Our Lithium SafeFlex batteries have specifically been utilized in onroad trucks in the US, electric vehicles across India, and in the material handling industry over the past 4 years. With over 30 years experience in Power, Green Cubes is an engineering driven company with its top focus on safety.

ABOUT GREEN CUBES TECHNOLOGY

Green Cubes Technology develops and manufactures a complete portfolio of lithium power systems that enable its OEM and enterprise customers to transition from Lead Acid and Internal Combustion Engine (ICE) power to Lithium-ion battery power. Green Cubes utilizes proven hardware and software platforms to build the most reliable lithium battery systems in its industries. With over 300 employees across six countries, Green Cubes has been producing innovative, high-performance and high-quality products since 1986. For more information, email info@greencubestech.com or visit greencubestech.com.

Overview

SAFEFlex is a drop-in replacement lithium-ion battery for lead acid battery power for electric material handling equipment. Temperature-controlled supply chain is more important than ever during with today’s volatile supply chain. On-line ordering of pre-prepared food, beverage clubs, and medicine distribution are all increasing the need for cold-chain technology. Lithium-ion batteries charge faster, and opportunistically, and have longer run-time than traditional lead acid batteries, optimizing equipment utilization Batteries don’t need to be swapped, watered, or equalized at room temperature, so maintenance is simplified. Cold-temperature cycle life is vastly improved for a lower total cost of ownership. This is a brief overview of how to implement and take advantage of this new technology.

The Cold Chain

Many products require constant refrigeration. Medicines, foods and beverages require cold transportation as well as storage and there is an increased strain on the cold storage industry as it adapts to increased fluctuations in response to on-line consumer habits, such as the new popularity of pre-prepared meal kits. For cold storage the insulated vehicle cargo area needs to be kept at a sub-zero temperature and the material handling equipment needs to operated within a refrigerated or freezer space.

The Challenges of Lead Acid Batteries:

Electric material handling equipment is favored for
indoor environments, but traditional lead-acid batteries pose significant challenges, e specially at extremely cold temperatures. The extreme cold temperatures can cause the battery electrolyte to freeze which lowers the usable capacity of the battery, as seen in the accompanying graph, which uses information commonly provided by lead-acid battery manufacturers. In addition, there is permanent damage to the battery and greatly shortening the battery’s cycle life.

…In order to operate the material handling equipment at such a low temperature, the fleet is connected to an electrical grid at night, resulting in significant under utilization.

In addition to normal maintenance, watering and cleaning the acid residue typical of flooded lead acid batteries, traditionally, in order to operate the material handling equipment at such a low temperature, the fleet is connected to an electrical grid at night, resulting in significant under utilization. Charge time for lead acid batteries is long and time is required to equilibrate the equipment between temperature extremes. If care is not taken, condensation can occur on the equipment creating icy and dangerous conditions for workers.

Implementing Li-ion Technology:

Unlike lead acid cells, Li-ion battery packs offer a complete solution with integrated smart communication, charging, and heaters to keep the battery at an optimum temperature. Green Cubes Technologies’ Lithium SafeFlex is a drop in replacement for lead-acid batteries with excellent cold temperature performance, high cycle life and safe operation.

When the battery temperature is lowered, the intelligent control system enables the heaters to prevent the battery temperature from reaching a temperature too low to charge and prevent cell damage.

When compared to traditional lead-acid batteries, lithium batteries charge faster, last longer, and deliver more usable energy with each discharge. Batteries don’t need to be swapped, watered, or equalized at room temperature, streamlining operations

The charge system (or cables) can be brought into the cold storage area, so that the temperature equilibration is not required and there is no more risk of dangerous condensation. Full charge time is only one hour and charging can be performed opportunistically. The same equipment is used for multiple shifts with no down-time, so the number of vehicles required is lowered and operating costs are lessened.

The zero maintenance SAFEFlex makes it possible to forklifts and other material handling equipment without interruption.

SAFEFlex batteries increase the velocity of distribution businesses with existing fleets of MH equipment including Walkie Pallet Jacks, End Riders, Narrow Aisle Forklifts, 3-4 Wheel Counterbalance Trucks, large Turrets, and other equipment. When compared to traditional lead-acid batteries, lithium batteries charge faster, last longer, and deliver more usable energy with each discharge. Batteries don’t need to be swapped, watered, or equalized at room temperature, streamlining operations and increasing efficiency at cold storage facilities.

SAFEFlex enables 100% uptime and utilization of your material handling equipment in cold storage and sub-zero environments.

	Lead Acid	Li-Ion (LFP)	Advantage of Li-Ion Batteries
Cycle Life	Low (~500-1000 cycles)	High (3000+ cycles)	Install battery for life of truck (no more swaps)
Charging Time	Slow (8 hours+)	Fast (60-90 minutes max)	Opportunity charge on-the-fly
Charge Efficiency	Low (~75%)	High (98%)	Lower electrical power costs
Energy/Volume Ratio	80 Wh/L	300-350 Wh/L	Smaller batteries
Energy/Weight Ratio	30-50 Wh/Kg	90-120 Wh/Kg	Lighter batteries & trucks reduce wear on power train
Partial Charging	Reduces battery life	No effect on battery life	Reduce down-time for battery charging
Consistent Voltage Output	Moderate	High	Extendes motor life, lowers motor maintenance
Depth of Discharge	Moderate	High	More run time per battery
Cold Temperature Performance	Low	High	More run time and less condensation in truck

Advantages of SAFEFlex for Cold Storage Usage:

• There is no cold-temperature capacity loss with integrated battery heaters.
• One-hour fast charging is enabled within the cold storage area (to -40 degrees).
• Forklifts will never leave the freezer, and palletjacks can be charged in refrigerated trailers, so risks from condensation are minimized.
• A permanently installed battery can support 24/7 continuous operation with an opportunity charging regime.
• Maintenance is minimal, unlike lead acid batteries.
• Cycle-life enables a useful product life of up to ten years
• A distribution partner with the knowledge to implement and maintain the battery systems makes execution easy and seamless.

ABOUT GREEN CUBES TECHNOLOGY

Green Cubes Technology develops and manufactures a complete portfolio of lithium power systems that enable its OEM and enterprise customers to transition from Lead Acid and Internal Combustion Engine (ICE) power to Lithium-ion battery power. Green Cubes utilizes proven hardware and software platforms to build the most reliable lithium battery systems in its industries. With over 300 employees across six countries, Green Cubes has been producing innovative, high-performance and high-quality products since 1986. For more information, email info@greencubestech.com or visit greencubestech.com.

Overview

Workplace injuries are all-too common in the warehouses and battery maintenance for material handling equipment is a typical culprit. The ongoing maintenance required to keep flooded lead acid batteries running presents a danger to the workers tasked with charging, watering and changing batteries. Batteries power equipment on construction sites, in tractors, trucks and automobiles, and most of them contain hazardous substances like lead and sulfuric acid. Unless workers who maintain, recharge, and operate batteries know the risks and how to mitigate them, they can suffer severe workplace injuries. New Lithium-ion batteries eliminate most of these issues because they are self-contained and maintenance free. Iron phosphate, a subset of Li-ion is the safest chemistry available, and its long cycle life means that it will last the lifetime of the truck.

Learn about:

• Hazards and precautions for lead acid batteries
• The safety features of Li-ion batteries
• The advantages of iron-phosphate Li-ion batteries

Lead acid batteries: Hazards, Precautions and Maintenance

The charging of lead-acid batteries is hazardous, but many workers may not remember this since the activity is so routine.
The three most common risks are from hydrogen gas formed when the battery is being charged, the sulfuric acid in the battery fluid- with exposure from spills and leaks, and physical injuries from the batteries’ weight. Repetitive use injuries, such as sprains and strains are common, but unfortunately the highly corrosive electrolytes in batteries can cause respiratory irritation, eye damage, skin irritation, and it can even erode tooth enamel. The sheer size of material handling batteries means that crush injuries also occur during battery changes. The corrosive electrolyte material is shown in the first image below of a damaged lead acid battery.
This is an overview of the risky maintenance for lead-acid batteries:

• The fluid level is extremely important and a safe level requires regular watering. Overwatering and underwatering can both damage the battery. If too much water was added before charging, the electrolyte levels will expand and cause the battery to overflow and damage the battery.
• Conventional batteries contain a liquid “electrolyte” which is a mixture of sulfuric acid and water. The plates in a lead battery contain an active material that should be continuously bathed in electrolytes while oxygen and hydrogen gas are released during charging.
• When batteries are being recharged, they generate hydrogen gas that is explosive in certain concentrations in air, so the ventilation system must provide enough fresh air to prevent an explosion.
• The electrical voltage created by batteries can ignite flammable materials and cause severe burns. Workers have been injured and killed when loose or sparking battery connections ignited gasoline and solvent fumes during vehicle maintenance.
• Wear personal protection equipment such as protective eyewear and gloves when working on batteries. To avoid splashing acid, personal protective equipment such as chemical splash goggles and a face shield must be worn.
• First aid facilities, eye wash stations, and emergency showers are necessary to reduce the severity of accidental contacts.

Safety Features of Li-ion batteries

Li-ion batteries are becoming more and more common because of their long cycle life and short charge times, but they also greatly reduce the risk to the workforce when they are implemented in a warehouse environment. Li-ion batteries are made up of cells, just like lead acid batteries. Large format Li-ion cells, used to manufacture batteries used for motive applications, are shown in the picture. The cells have an anode and a cathode with a separator and electrolyte in between. Unlike flooded lead acid cells, the li-ion cells are sealed and have many safety factors designed in them. The cathode material is the main determining factor in the cell’s performance. In the battery power market today there is a myriad of available battery cathode chemistries to choose from. It is a critical decision which not only impacts how well the product will operate but also how safely it can operate. Factors such as how much power is required, the time required to charge, operating temperatures, operating environment, packaging dimensions, and weight are all examples of key parameters that must be considered.

Li-ion batteries are becoming more and more common because of their long cycle life and short charge times, but they also greatly reduce the risk to the workforce when they are implemented in a warehouse environment.

While higher energy li-ion chemistries are available, Lithium iron phosphate (LFP) is safest with the longest cycle life due to its stable chemical make-up. A demonstration of how much more stable the LFP chemistry is compared to the high energy Lithium Cobalt Oxide (LCO), used in consumer electronics, is to compare the thermal runaway temperatures- the high temperatures at which the chemistries begin to become unstable and volatile. LCO has a much lower thermal runaway temperature of 150°C (302°F) compared to LFP’s thermal runaway temperature of 270°C (518°F). This large difference shows LFP to be the much safer of the two lithium chemistries.

High energy density is important for battery systems which need to be smaller and lightweight. A more modern cathode chemistry than LCO is Nickel Manganese Cobalt (NMC). NMC is the result of an attempt to balance safety and performance. A version of NMC is the chemistry is utilized in automotive EV battery systems today. EV batteries utilize higher voltages and with the higher energy available, additional safety measures and control must be implemented. The cells heat up quicker, so proper charging is critical.

With larger industrial, motive power battery systems, space is available for the larger batteries, and weight is actually needed for the counterbalance systems. Fast charging is critical and LFP accommodating lead acid charging helps with systems safety. Cycle life and safety is prioritized. The lower voltage of LFP is good match for Lead Acid replacement. This and the tolerance of Lead Acid charging systems make LFP the safest backward compatible option for material handling batteries.

The physical construction of the cell also affects its safety. All lithium batteries contain a critical component called the separator, which is placed in between the anode and cathode layers in the electrode. The separator limits the chemical reaction of the electrode and helps to prevent thermal runaways by closing its porous structure at high temperatures. The safest Li-ion cells incorporate ceramic separators. The ceramic material is resilient at high temperatures and helps prevent the breakdown of the separator that occurs during a thermal runaway event.

The electronics of the Li-ion battery also provide protection against safety events, with incorporated fuses and protection against over-charge, over-discharge and high and low temperature charging. These battery “smarts,” combined with the long cycle life and short charge time seamlessly integrate with the material handling equipment. The fact that the battery is virtually maintenance free over the life-time of the truck, eliminates the possibility for user error and greatly reduces the risks in the workplace.

With larger industrial, motive power battery systems, space is available for the larger batteries, and weight is actually needed for the counterbalance systems. Fast charging is critical and LFP accommodating lead acid charging helps with systems safety

LFP VS. NMC

Parameter	Lithium Iron Phosphate (LFP)	Nickel Manganese Cobalt (NMC)	Comparison
Voltage	3.2 V	3.7 V	NMC Batteries are lighter and more compact
Weight Energy Density	90-120 Wh/Kg	150-250 Wh/Kg
Volume Energy Density	300-350 Wh/L	500-700 Wh/L
Max Discharge Rate	30C	2C	LFP Batteries provide more power over a shorter period, and can be charged faster
Max Charge Rate	10C	0.5C
Typical Cycle Life (@80%)	3000+ Cycles	500-1000 Cycles	LFP Batteries will deliver more cycles over a longer calendar life
Calendar Life (@80%)	8-10 Years	**4-5 Years
Thermal Runaway Onset*	~195 °C	~170 °C	NMC Batteries have lower thermal runaway thresholds and will burn hotter
Thermal Runaway Increase*	210 °C	500 °C
* Royal Society of Chemistry, 2014 ** With derated charge voltage

YOUR NEXT STEP

Our engineers can help you identify areas of your operation where Lithium SAFEFlex can make the most impact, based on how you use your fleet:

1. We’ll evaluate your facility to see where changing from Lead Acid to Li-ion will most impact your organization. Our analysis will cover number of vehicles, number of shifts, charging information, and major improvements you’d like to see.
2. We’ll provide a quote to demonstrate that there will be a cost savings associated with the change to Li-ion and it’s safety benefits, then we’ll provide a trial system with monitoring software to validate the savings.

ABOUT GREEN CUBES TECHNOLOGY

Green Cubes Technology develops and manufactures a complete portfolio of lithium power systems that enable its OEM and enterprise customers to transition from Lead Acid and Internal Combustion Engine (ICE) power to Lithium-ion battery power. Green Cubes utilizes proven hardware and software platforms to build the most reliable lithium battery systems in its industries. With over 300 employees across six countries, Green Cubes has been producing innovative, high-performance and high-quality products since 1986. For more information, email info@greencubestech.com or visit greencubestech.com.