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What’s Under the Hood in Electric Equipment Reduces Total Cost of Ownership

by: Lars Arnold, Product Manager — Sustainable Power, Volvo Construction Equipment
Battery racks in the Volvo ECR25 Electric Excavator
Battery racks in the Volvo ECR25 Electric Excavator
Left side of the Volvo ECR25 Electric Excavator
Left side of the Volvo ECR25 Electric Excavator
Volvo ECR25 Electric onboard charger
Volvo ECR25 Electric onboard charger
Rear side of the Volvo ECR25 Electric Excavator
Rear side of the Volvo ECR25 Electric Excavator
Much has been said about the value of electric equipment in terms of its lack of emissions, lower noise and vibrations, and the ability it provides to work in spaces and applications you previously could not. Still, its higher purchase price leaves some questioning whether it’s worth the switch.

If you’re looking for more evidence that electric construction equipment will benefit your bottom line in the long run, look no further than under the hood. To put it simply, these machines require almost no maintenance.

No Idling
One major advantage of electric equipment is that it shuts off when not in use, so it’s not racking up idle hours like a diesel machine that needs to keep fuel and fluids moving. When you need to get working again, it starts right back up. The immediate torque provided by electric power versus the slight delay that comes with diesel is one of the things early users have noticed most. As a bonus, no idle time also helps reduce the total cost of ownership and improves resale value.
Fewer Supplies
Because there is no engine or fuel system, filters and DEF are not needed with electric machines. Essentially, the only supplies required are hydraulic oil and grease, which is much different than a conventional machine that requires fluid, filter, and component checks as often as every day, with additional cyclical preventive fluid and filter maintenance.

There is no difference in the maintenance of non-electrical components like hydraulic pumps and hoses. However, before performing maintenance on the non-electrical components, a risk assessment process is required, just like it is for the electrical components. Even though the work may not directly involve the electrical or battery power systems, there could still be inherent risk. Which is why…

Some Training Required
Electric components like the lithium-ion battery, DC to DC power converter, inverter (AC to DC to charge the traction batteries), battery management unit, and charging plug just need visual and functional inspections. Any components not working would be replaced, not repaired.

When diagnostics reveal a need for component removal or other maintenance, a risk assessment is performed by a qualified technician and the traction voltage system is disconnected and decommissioned. This should only be performed by people who have completed a thorough certified training program.

Because we’re talking about machines using electricity, most of the training will be about safety. Some of the concepts that are important to learn include how an AC three-phase motor functions, Ohm’s law (the relationship between voltage, current, and resistance in a circuit), Fleming’s left- and right-hand motor and generator rules, and the effect that current flow has on a magnetic field. Other topics unique to electric machines are inverter function, onboard charging system operation, and how a lithium-ion battery works (see “A Closer Look at Lithium-Ion Batteries” below).

Your local Finn Corporation dealer
Romco Equipment Co

This may sound like a big shift in what technicians need to know, but it’s part of our ever-evolving industry. It’s just like when telematics and in-cab displays entered the picture — technicians had to learn how to service those as well. When you consider the complexity of internal combustion engines, the differences between diesel and gasoline engines, differences between two- and four-stroke engines, and the fact that engines have an average of 2,000 moving parts, perhaps electric machines don’t seem so complicated.

Valuable Alternative
Overall, the lifetime of battery-electric components should be equal to or better than that of the diesel engine on a conventional machine. My company conservatively estimates that users will see a 35 percent savings in maintenance costs and time over the life of the machines we offer. And warranties for electric components can provide extra peace of mind.

Although the shift to electric requires some training, the maintenance needed for these machines is much simpler and less frequent. With electrification expected to continue growing, it’s a worthwhile investment for many reasons.

A Closer Look at Lithium-Ion Batteries
The lithium-ion (or li-ion) traction battery inside an electric machine is obviously a significant component of its operation. While there isn’t much to maintain, it helps to understand how it works for safe handling and use.

These rechargeable batteries are named for the lithium ions that move between two electrodes during the charging and discharging cycles to store and release energy.

Battery Anatomy
First things first: Electricity cannot be captured and stored. It must be converted to another energy form (e.g., chemical energy) which can then be stored.

In an internal combustion engine, the bond energies within gasoline or diesel molecules are broken and converted to heat, which transforms into the mechanical energy needed to drive the piston. Similarly, batteries store electricity from the power grid in the form of chemical potential and then discharge energy to provide electricity.

Lithium-ion batteries contain four main components:

  • Anodes (the negative end) store and release lithium ions from the cathode during charging; conversely, they release lithium ions during discharge. They’re typically made of graphite.
  • Cathodes (the positive end) serve as the origin of lithium ions, playing a crucial role in determining the battery’s capacity and nominal voltage. They’re typically made of active material, e.g., NMC (nickel, manganese, and cobalt), NCA (nickel, cobalt, and aluminum), or LFP (lithium, iron, and phosphate).
  • The separator divides the anode and cathode and prevents direct contact between them.
  • The electrolyte provides lithium-ion conductivity. It’s a chemical solution that transports lithium ions and prevents the electrons from going straight from the anode to the cathode within the battery.

A battery must be connected to an external circuit to absorb and release energy. Electrons move through the external circuit while lithium ions move through the electrolyte.

How Li-Ion Batteries Work
Let’s take the current, widespread adoption of lithium-ion chemistries, NMC, as an example:

  • During charging, electrons accumulate at the anode (electricity is converted into chemical potential).
  • This results in an electrical difference between the anode and the cathode. Think of this as an unstable build-up of the electrons.
  • The oppositely charged lithium ions move inside the battery from the cathode through the electrolyte to balance the charge.
  • While the battery is discharging, the anode releases lithium ions to the cathode, generating a flow of electrons from one side to the other. It converts the stored chemical potential energy to electricity in the circuit and discharges the battery.

This may still seem a bit complicated, but that’s mainly because it’s new to our industry. The batteries and motors themselves are not new, though — they’ve been proven in several other industries. With time and experience, it will all start to make more sense and the realization of simpler maintenance will come into view.

Your local Wirtgen America dealer
Nueces Power Equipment
Kirby Smith Machinery