By Warren Miller, Marine Construction Magazine
It’s no secret that the construction industry is moving to electrically-powered equipment. The challenges of electric power, however, are much greater for heavy equipment than they are for smaller machinery. And the top priority is ensuring that sufficient power is available in the field—in the batteries or through nearby chargers—to complete an eight-hour shift in the field.
“The transition to electric drive is becoming more popular in the construction industry due to emission regulations, advancements in lithium battery technology and the opportunity for clean indoor operation,” according to Delta-Q, a company that manufactures a wide range of charging units.
One of the greatest challenges to widespread adoption of electrically powered equipment—as it is with the adoption of the electric automobiles—is charging. Recharge or swappability are key factors in choosing the power capability of electric equipment.
Marine Construction Magazine spoke with Mourad Chergui, an electrical engineer by training who is a senior product manager at Delta-Q, about their battery chargers. Mourad joined Delta-Q in 2016 and has over 25 years of experience in product management across engineering, marketing, business and administration in various industries. At Delta-Q, he spearheads new product strategies across power conversion, battery charging, vehicle electrification and regulatory standards.
The information in this article came from a telephone interview with Chergui and from transcripts of a webinar that Chergui and other Delta-Q staff presented in Las Vegas last March in conjunction with CONEXPO.
MCMag: What percentage of heavy-duty construction equipment is electric today?
Mourad Chergui: For heavy equipment, the percentage is very low, less than one percent. That’s because of the complexities and the size of the batteries. There is a lot of electrification happening right now in the compact size. But in heavy equipment, the expectation in is that electrification will reach 20 and maybe 30 percent by 2030.
MCMag: What are the breakdowns as to power levels of electrical equipment?
Chergui: There are some standard voltages when it comes to electrification, and they fall into five categories. What are known as “low voltages” are those below 60 volts. Typically, it’s a 48-volt nominal. Then there are what we call “intermediary voltages.” This includes 72-, 80-, and 96-volt nominal. Then “medium voltages” are for 300 to 450 volts. And then there is the “high voltage” category where the voltages extend from 500 to 850 volts. And then there are higher voltages that are typically above 1,000 volts. There is no standardization in the industry on any particular name.
The majority of electrification of machines is happening with low and intermediary voltages. And there are two categories. There is the standardized low voltage category below 60 volts, which inherently is called and considered to be touch-safe. This type of voltage allows simple designs and costeffective solutions. It is suitable for what we call subcompact vehicles, vehicles with nominal power up to 25 kilowatts. These vehicles also have the advantage of being able to be maintained and repaired in regular service shops.
Then there is another category still considered to be low voltage with voltages from 72 to 96-volt nominals. These voltages have been used for decades in various industrial and light mobility applications. These voltages ranges are ideal for compact to midsize vehicles with nominal power expanding from 20 to 75 kilowatts.
The advantage of these voltages is that it avoids the component costs and design complexities associated with higher voltages, namely 400 volts. And there is quite a variety of components sold by many OEMs in the industry for commercial, off-the-shelf components and systems. These low and intermediary voltages allow for achieving effective machine performance in the subcompact and compact equipment. They present a simple and shorter development design cycle. The components are widely available from several vendors. And in general, and that’s actually the biggest advantage, the total production cost of the machines is relatively lower. And depending on the application, it goes from 5- to 10-percent less expensive than similar vehicles built with a 400-volt power system.
MCMag: How does the amount of power impact the charger market?
Chergui: In the domain of heavy construction equipment, swappability is of limited use because batteries are completely on the vehicle. What they are opting for is either to have fast charge or bigger batteries. Swappable batteries more common in material handling market.
On a construction site, it’s difficult to do swappable batteries. The batteries are on vehicles permanently. The solution is fast recharging during working hours.
MCMag: Can most light construct equipment today be charged to work a full day?
Chergui: It’s certainly the intent of all manufacturers to allow for at least an eight-hour shift. What we’re hearing from manufacturers is that they also want to permit quick-charge on the job site during breaks.
MCMag: Are lead-acid batteries being phased out?
Chergui: In construction equipment, yes. Most equipment is using lithium ion. Lead-acid batteries are used on some material handling equipment, especially large container handlers, but most are going to lithium.
MCMag: Are chargers that can recharge multiple battery types by changing settings and algorithms common?
Chergui: Yes, that’s common in high-frequency chargers. It’s not just the ability to change the algorithm, but the ability to test those algorithms. Delta Q prides itself on that work. We have a very large battery test lot. It’s not enough to have something that’s theoretical or designed—you have to test it to ensure that performance is achieved.
MCMag: I guess it’s better to run tests at your test site than to have a failure in the field?
Chergui: It’s not just failure, it’s performance. We want to ensure that the battery gives its best performance to the application through the life of the battery.
MCMag: How do you choose the right voltage for different types of equipment?
Chergui: The considerations are first, the size of battery; it has to be able to fit on the equipment. That’s one of the important ones. Second is the performance required. Typically, the smaller the equipment, the less voltage needed, and vice versa. Another really critical factor is the size of the battery and how fast it will run charged, because there are physical limits to charging speed.
It’s safety and complexity balanced with size and speed. Those are two different dimensions that the OEMs struggle with to choose the appropriate voltage for the application.
MCMag: Are the safety training requirements for 800 volts different from what is needed for 400 volts regarding the assembly and service personnel?
Chergui: Yes. At 400 volt levels, there are standards which allow actually some of the systems to be exposed if there are certain protections implemented. In the 800 volt levels, there absolutely should be no contact with live parts. The hazards are very different. At 400 volts, if the current is interrupted within, let’s say, 20 milliseconds, and there is a device there, there will be no or few consequences. With 800 volts, any exposure could be potentially very harmful. So yes, the training and the equipment have to change moving from 400 to 800 volt levels.
MCMag: How do you think off-road equipment will be charged in the future at job sites that are away from any public charging infrastructure?
Chergui: I see using private charging stations that are designed for outdoor use and can be installed on a temporary basis at a construction site. I do see that as the best solution because at this point, it’s the way to provide the most reliable and rugged solution that we have. Mobile EV charging stations can be temporarily installed and then connected by an electrician on the site, and then removed when they finish on the job site. Then it can be taken and moved to another location. There are solutions that are available today that offer the robustness and the safety necessary for job sites.
MCMag: Will 800-volt equipment replace internal combustion engines?
Chergui: I don’t think that internal combustion engines will be eliminated in the short term. The reason is that there are other combustible technologies, such as bio-diesel and hydrogen. But even in the long-term, combustion engine use will be decreased but not be completely eliminated.
Reprinted from Marine Construction Magazine Issue V, 2023.
