Could Mobile Batteries Enable Electric Construction Vehicles and Enhance Grid Resilience?

The researchers are also studying the mobile batteries as a source of backup power in the event of a grid outage. These batteries, which range from 250 kWh to 600 kWh, contain enough energy to keep a moderately sized office building powered for a couple of hours. If you had several mobile batteries, they could be daisy-chained together to keep critical infrastructure — like a hospital or fire station — powered up for longer stretches of time. This setup could potentially replace backup diesel generators, but needs to be studied to determine exactly how long one battery could power different buildings with different energy profiles, as well as to identify any power quality issues, such as the introduction of harmonics.

Another pro of portable batteries, in addition to not having to move large construction equipment? They can be recharged when there’s the least demand on the grid, or when renewable energy, such as solar power, is most readily available. 

Electric construction vehicles have been rolled out in various pilot projects — including during construction of the new San Diego International Airport Terminal 1. But these electric backhoes, excavators and bulldozers have so far relied on traditional charging stations, like those you might plug your electric car into at the office or at a supercharging station. Instead of having to transport these massive vehicles to a stationary charger, the UC San Diego team is studying the effectiveness of bringing a mobile battery to the construction site to meet the vehicles where they are. 

“Mobile battery research like UC San Diego’s EPIC project could advance significant progress toward California’s goal of achieving 100% of the state’s electricity from renewable and zero-carbon sources by 2045," said Jonah Steinbuck, Director of the Research and Development Division at the CEC. "We’re excited that the project strives to demonstrate how mobile battery innovation might more effectively integrate renewable energy sources into the existing power grid and better optimize our energy supply for greater affordability, accessibility, and resilience."

Yuanyuan Shi, assistant professor of Electrical and Computer Engineering at UC San Diego and principal investigator of this research project, is leading the effort to study these batteries’ viability as a power source for electric construction vehicles and to gather data on their power, charging and recharging capabilities. The research team is also developing an AI assistant to help construction sites optimize charging schedules for equipment and mobile batteries — reducing costs, emissions, and downtime. Batteries from several companies will be studied as part of a demonstration construction project at UC San Diego planned for later this year.

“Construction sites have unique charging needs that can’t always be met with fixed EV charging infrastructure. The goal of our project is to develop scalable solutions that make electrifying construction equipment practical,” said Shi. “With mobile batteries and advanced optimization and AI tools, we can align charging with renewable generation, reduce grid stress, and cut air and noise pollution — all while minimizing disruptions to construction schedules and accelerating the transition toward cleaner, more sustainable job sites.”

This effort to study these portable battery systems’ use in a battery-to-grid (B2G) energy storage use case scenario is possible thanks to the unique plug-and-play capabilities of UC San Diego’s Distributed Energy Resource Connect (DERConnect) testbed. At DERConnect, researchers and industry partners can bring their own hardware — like these mobile batteries — and simulate plugging it into an actual, functioning electric grid under various planned conditions. In this case, companies including Saniset and Smartville brought their mobile battery systems to the DERConnect testbed to have the researchers put them through various tests.

“The DER Connect testbed is really unique because you can bring in your own hardware and run tests that leverage both our power systems laboratory and our integration with the UC San Diego microgrid,” said Keaton Chia, project manager at DERConnect. “We’re working with startups, utilities, manufacturers, and companies like these that rent mobile batteries. In this case, we used real building meter data from campus and are able to emulate those load profiles with our load bank to test the performance of the batteries in real-world scenarios. By plugging them into the testbed, we can also capture high-fidelity data during the test and make use of other systems like our grid emulator, simulators, and our own stationary battery systems.”