Battery Basics: Understanding the Battery Technology Powering Today’s Electric Construction Equipment

Vanguard lithium batteries

Battery-powered construction equipment will continue to be the hot topic of 2023. Almost every major off-highway equipment manufacturer is proudly showcasing an electric unit these days, and now almost every category of compact equipment offers an electric-powered variant — mini excavators, compact track loaders, telehandlers, wheel loaders, utility vehicles and aerial lift equipment of all types. On the earthmoving equipment side, each brand seems to specialize in a category. Bobcat offers its electric-powered T7X compact track loader. Toro has its e-Dingo 500 compact utility loader and e2500 electric ultra buggy. Volvo Construction Equipment offers two electric compact wheel loaders and three electric mini excavators. Big brands are making big moves in this sector.

“As John Deere works toward a future with low- and near-zero-carbon solutions, we are investing significant resources in advanced battery technologies for off-highway vehicles,” explains Preston Moore, solution planner and product manager for electrified drivetrain and propulsion batteries at John Deere Power Systems. “To better support our OEM customers in meeting their electrification goals, we’ve acquired majority ownership of Kreisel Electric, a battery technology provider based in Austria. Kreisel is a pioneer in the design, validation and manufacturing of battery modules and packs in the emerging space of off-road electrification.”

It’s not just the machine makers that see the potential and importance of battery technology. On the OEM side, traditional gas and diesel engine manufacturers are also announcing battery products to go into construction, landscape, ag and rental equipment. Both Caterpillar and its compact diesel expert Perkins recently showcased the development and field testing of 48-volt, 300-volt and 600-volt battery configurations that can be leveraged in compact equipment. Brands like Vanguard already offer a competitive range of commercial battery packs.

“The newest additions include the lithium-ion 1.5-kWh Swappable Battery Pack and the 3.5-kWh, 5-kWh and 7-kWh Diecast Commercial Batteries,” says Nick Moore, director of sales- electrification at Briggs and Stratton, which owns the Vanguard brand. “The 1.5-kWh Swappable Battery Pack will have an immediate impact on the off-highway industry when it hits the market in May 2023. Engineered to provide users with an efficient, versatile and reliable battery power option, the battery’s exchangeable design allows customers to swiftly swap freshly charged packs from application to application. The new 3.5-kWh, 5-kWh and 7-kWh batteries from Vanguard all feature a diecast aluminum casing design that adds rigidity and reduces vibration and shock response from the pack. These batteries will be available for order beginning in January 2023.”

Since everyone’s talking about electrified compact equipment these days, we thought it would be a good opportunity to take a serious look at the battery technology behind this market revolution — chemistry, options, charging, maintenance, monitoring and beyond. Let’s get plugged in.

The Pros of Battery-Powered Construction Equipment

Volvo EC55 excavator

For a variety of reasons (regulations, fuel prices, environmental concerns), Europe is one of the most progressive markets to embrace battery-powered construction equipment. Euro brands from JCB to Wirtgen are currently selling electric equipment in Europe and beyond. Volvo Construction Equipment is one of the market leaders. Volvo currently offers five electric compact machines — two compact wheel loaders and three compact excavators — and has announced it is committed to stopping new diesel engine development of mini excavator models globally from the EC15 to EC27 and compact wheel loaders from the L20 to L28.

“In fact, Volvo had the first commercially available fully electric excavators and wheel loaders on the market, and North American deliveries started in summer 2022,” says Lars Arnold, product manager-sustainable power at Volvo CE. “We’ve had sales across the U.S. and Canada, from coast to coast. There’s definitely strong interest in areas with emissions regulations like the West Coast, but as I said, we’ve been selling units throughout North America. We’ve also been selling them into a variety of segments including general construction, government fleets, landscaping, farming and more. The versatility of applications is one of the things that’s really stood out so far.”

The reasons to embrace battery-powered equipment are many — emissions sensitive applications (like indoor work), low-noise jobsites (say next to a hospital), easier operation (low vibration and noise), lower fuel and maintenance costs and sustainability goals. Rental seems to be a big channel for battery-powered equipment with big chains like United Rentals and Sunbelt partnering with machine makers to push electric compact equipment into the market (beyond MEWPs).

Toro eDingo 500

“Larger municipalities are driving the shift to electric, especially on the coasts and in areas where emissions regulations are in effect,” says Sam Dando, product marketing manager at Toro. “As far as industries, we’re seeing large rental companies be among the first to incorporate battery-powered equipment into their fleets. These rental operations are citing sustainability and total cost of ownership as driving factors. Rental equipment is only making money when it’s on a jobsite, so the lower maintenance needs of battery-powered equipment is a real advantage that translates to fewer hard costs and less downtime.”

Of course, there are a variety of electric technologies on the market. There are some tethered or cable-powered electric units like Cat’s 300.9D VPS dual-power compact excavator that can switch between a diesel engine or a cable-powered electric motor. There is other hybrid electric equipment on the market like Genie’s hybrid telescopic and articulating boom lifts, which can work in diesel and electric modes with the use of 48-volt battery packs, 24-hp diesel engines and intelligent control systems. This article will focus on battery electric vehicles that use one or more internal batteries to power motors and hydraulics that move a piece of compact equipment and its attachment.

Lithium-Ion Is the Battery of Choice

Even though manufacturers are marketing battery electric earthmoving equipment heavily in 2023, there still aren’t very many units on the market. When going to a rental house or dealer, they may have only one option in a few key categories. When it comes to battery electric earthmoving equipment, these e-machines are usually an electric variant of a diesel unit that sports the same specs. When it comes to power and performance, Volvo’s ECR25 electric excavator and L25 electric wheel loader specifications are nearly identical to their diesel counterparts. The major difference is the battery, so a renter or buyer should sit down with a professional to discuss how the battery system works on each individual model, as technologies will vary.

“Our electric machines operate on a 48-volt traction battery system where the different models have different battery capacities,” explains Najing Li, product manager-sustainable power at Volvo CE. “The L25 electric has six racks and a total of 40-kWh battery capacity. The L20 has five racks and 33-kWh battery capacity, with an optional sixth rack for a total of 40-kWh battery capacity. The ECR25 electric has three racks and a total of 20-kWh battery capacity. The short tail ECR18 comes with 16-kWh battery capacity, and the standard tail EC18 with 20-kWh battery capacity.”

Battery capacity is defined as the total amount of electricity generated due to electrochemical reactions in the battery and is typically expressed in ampere hours (Ah) in off-highway construction equipment. The energy a battery delivers during the discharge process will give you its indicative runtime. For Volvo’s L20 electric wheel loader, the standard 33-kWh battery capacity will give an operator four hours of indicative runtime, depending on the application. The optional 40-kWh battery capacity will give an operator six hours of indicative runtime, depending on the application. The design and chemistry of these batteries is also important to understand.

“Not all batteries are created equally, especially when it comes to the advanced chemistry and technology that make up today’s lithium-ion batteries,” says Nick Moore. “There are numerous variations in design and chemical composition when producing a lithium-ion battery pack. Vanguard, for example, engineers its battery packs to account for what could happen under non-perfect conditions, starting with cell module assembly and cell selection. We use cylindrical cells, which have a current interrupt device [CID] built into them. The CID reduces the risk of thermal events by isolating a cell that may be encountering an issue so that the problem doesn’t spread to other cells. Another level of safety built into Vanguard batteries is the physical spacing between the cells. By creating an engineered amount of space, we’re again helping to ensure a problem in one cell doesn’t propagate to the next cell.”

While lead-acid batteries are still common in many of today’s battery-powered mobile elevating work platforms (MEWPs), lithium-ion seems to be the industry standard for electric powered earthmoving equipment like excavators and wheel loaders. The lithium-ion technology used in today’s batteries is far superior to the lead-acid or nickel-cadmium technology on MEWPs, older electric hand tools and some electric vehicles. Lithium-ion batteries are a lot more forgiving and have no memory effect, which is the reduction in the longevity of a rechargeable battery’s charge due to incomplete discharges in previous uses.

“Lithium-ion batteries have a much larger usable range in terms of capacity than, for example, a lead-acid battery,” notes Nick Moore. “Typically, you can only use about half of the capacity in a lead-acid battery, whereas with lithium ion we’re able to get upwards of 93+ percent efficiency. The self-discharge rate, which is the discharge that occurs while the battery is in an open-circuit condition, also outpaces lead acid. Lithium-ion batteries also hold a charge longer and have a more robust cycle life. After 500 cycles, a lead-acid battery is down to about 80 percent capacity. It takes 2,000 cycles before a lithium-ion battery is at the same 80 percent capacity. What this means for our customers is they have to replace lead-acid batteries halfway through the usage case with another fresh set of lead-acid batteries, whereas lithium ion lasts the entire life of the product. Also, lithium-ion batteries have a second life in them, meaning that at the end of their life cycle there is still about 80 percent battery capacity left. Batteries can then be reused safely in other applications.”

Genie GSE scissor lift

There are also options within the lithium battery category, but the majority of the industry touts lithium-ion technology. As an example: Genie offers a lithium iron phosphate mixture on some of its scissors. The chemistry and design of the battery is important to understand — as important as understanding a Tier 4 Final diesel engine. For instance: Toro’s eDingo 500 compact utility loader and e2500 electric ultra buggy use the company’s proprietary HyperCell battery system.

“The Toro HyperCell Power System is a high-energy battery system modeled after the batteries automakers rely on,” says Dando. “It’s designed to match the lifetime of the equipment, including their gas or diesel power counterparts. Each HyperCell battery is de-energized by default and provides diagnostic information to streamline service. We also lean on third-party testing expertise and UL certification to validate our battery and overall machine design. The distributed battery management system [BMS] optimizes battery performance to enhance reliability, and because the BMS is integrated, HyperCell batteries communicate with each other to place a priority on efficiency and extended life. Our patent-pending battery design and distributed BMS are engineered to reduce the risk of accidental shock by de-energizing them by default. This also helps regulate the battery charge, discharge and temperature, which helps prolong the life of our battery.”

Temperatures and Battery Management

Kreisel module

Battery packs may include an internal battery management system or BMS, which might continuously check things like voltage and temperature to make sure the battery is working safely and efficiently and/or provide data on power utilization while allowing integration with Internet of Things (IoT) devices. Each battery will have its own temperature range it is able to operate in. It should be noted that this is typically the cell temperature, not the ambient temperature, so having a capable BMS monitoring the cell temperatures is important.

“Most cells can discharge to a lower temperature than they can charge, so it is usually a best practice to put a battery on the charger at the end of use prior to an overnight cold soak,” Nick Moore says. “Heating a compartment a battery is in is an option for continued cold use, as well as there are thermally managed batteries on the market. Our Vanguard battery packs do well on the hot side, and that is one of the benefits to our aluminum enclosures.”

As temperature is so important, enclosures can be as crucial as heating or cooling technologies. John Deere-owned Kreisel offers its patented immersion cooling system that enables a significant improvement in battery life. Some of the key improvements include: the lowest temperature spreads of less than 1°C on pack level, avoiding early single cell aging; superior lifetime under high loads in fast charging, high-performance and hybrid modes and applications; and precise temperature ranges that ensure constant best conditions for extreme cell operations.

“Battery cells have different internal resistances at different temperatures,” says Preston Moore. “Depending on the internal resistance, the current load is also unbalanced. Over a longer period, during which the cells are stressed differently, the aging effects are also unequal. Since the weakest element in the overall system, the oldest cell, always determines the performance and battery life, it is important to us to keep the cells at an optimum temperature and charge them with a feel-good temperature, as well as keeping them at an identical temperature level. We call this ‘the one-degree challenge.’”

Charging Options

Benning DC rapid charger

Properly charging a battery-powered machine will be important for its daily usage and longevity. First off, there will be charging options. There may be on-board or off-board charging, stationary and mobile fast-charging and even solar powered charging options available. Almost all battery-powered earthmoving equipment will have an on-board charging option, which is an AC charging system that uses an on-board charger mounted inside the machine. An on-board charging system might plug into a standard 120-volt wall outlet or a 240-volt, level 2 AC outlet system, which will determine how fast the battery will charge. A Volvo ECR25 electric excavator will take 12 hours to charge on a common household 120-volt outlet and six hours on a 240-volt setup.

“The ideal choice for Volvo electric equipment is a 240-volt, 32-amp Level 2 AC charging setup, but a household 120-volt outlet or off-board fast charger are good options too,” says Li. “There are a few other additional options and things we are working on. For example, we offer a Beam solar fast charger which is an off-grid, free-standing charger with a battery pack similar to the size of the one inside the L25 electric CWL. We’re working on a Benning DC rapid charger, which reduces the ECR25 electric charging time to one hour and the L25 electric to two hours, from empty to 100 percent full. We’re also working on the Powerbank container, which is a movable power bank, not yet commercially available, that we are currently testing in select markets for charging mid-size electric machines.”

Off-board chargers take it to the next level, offering the quickest charge times, noting quick charges can affect battery life. Off-board systems are converting AC to DC electric, supplying the required regulated DC power directly to the batteries from a charger outside the unit. An off-board charger usually looks like a big metal rectangular box. It could be portable, equipped with a lifting eye and may have enclosure and cover options.

“One great thing about the portable options is that they don’t typically require a permit or specific installation process,” says Li. “Plus, they don’t draw from the grid, so they avoid peak usage times/costs and avoid power fluctuations. And of course, they are also quiet and zero emissions.”

JCB is one of the most forward-thinking equipment makers when it comes to electric-powered construction machinery, and the company sells a portable off-board universal fast charger for 48- to 96-volt machines, promising to fully charge units within 2.5 hours. These off-board systems might require a three-phase power supply vs. a traditional residential singe phase power supply. There are also portable battery power packs.

“Every user has a very different scenario they are trying to accomplish,” says Nick Moore. “Depending on the size of the equipment, there are likely different charging options available which can greatly change the way a user interacts with the unit. There are differences in on-board vs off-board, how the user interacts with the cable to machine interface and what kind of power source is needed.”

As for when to charge, it will depend on your application. Machines are designed to perform on one charge all day, but harsher environments might require a quick charge over lunch or breaktime. It’s a best practice to charge batteries from mid-level to full, as opposed to draining the battery completely before recharging. Another tip is not to run the electric machine at full throttle all the time, which could also be applied to diesel-powered equipment. Overall, the unit will run a lot less than diesel units, which waste fuel and engine hours while idling. Battery-powered construction equipment should have an anti-idle/auto shutdown system, which turns it off after so many seconds without working. One final insight…

“The best for the battery life is AC Level 2 charging, which is slow charging, versus DC fast charging — but again, it’s all about a customer’s needs,” says Arnold. “It’s not killing the battery. It’s just that you can extend the lifespan of the battery with slower charging. We don’t yet know how long the batteries will last in electric construction equipment because the technology is new to the construction equipment industry, but it’s important to know that lithium-ion battery powered cars and the battery technology itself has been out for decades. With this, we estimate the battery will likely last somewhere around 10 years.”

Keith Gribbins is publisher of Compact Equipment.

120 vs. 240 Volt

outlet diagram
The image on the right has the higher kilowatt output and is not difficult to install. The image on the left is the type of outlet most people are familiar with and probably have.

By Najing Li, Product Manager-Sustainable Power at Volvo CE

electric equipment charging chart

All charging times are approximate from empty to full.

Volvo Construction Equipment recommends a 240-volt, 32-amp Level 2 AC-charging setup utilizing an SAE J1772 charging adapter or J plug — the same as for electric vehicles. The image to the right shows the NEMA 5-15 and NEMA 14-50 electrical outlets that are recommended for AC charging. These are the two outlets Volvo makes J plug adapters for.

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