Hybrid and electric vehicles are being eyed by the military, which has often found it difficult to supply fuel when many vehicles are on the move. But a number of challenges must be overcome before warfighters see electrified vehicles in the field.
The U.S. military has developed demonstrator vehicles and many transportation companies have produced vehicles that augment internal-combustion engines (ICEs) with electric or hydraulic power. But broader adoption appears to be a fair ways out in the future. When the topic of hybrid and electric vehicles came up during the SAE Commercial Vehicle Engineering Congress in Rosemont, IL, in September, panelists cited a number of issues that must be resolved before electrified powertrains see use in most military environments.
Military and commercial representatives gathered in a Blue Ribbon Panel titled “Commercial Vehicle Integration for Military & Homeland Defense Applications” said there’s definitely interest, since delivering fuel is an expensive and sometimes hazardous aspect of military operations. Panelists from the commercial side noted that as interest in electrification increases, they are forging partnerships to help develop electric subsystems.
“We’re refocusing our effort on power management, partnering with companies that give us complementary technologies,” said Lennart Jonsson, CTO for Eaton Corp. “Our university partnerships also continue to expand.”
Designing components and subsystems for military vehicles always requires more ruggedness, but other parameters are also far more demanding. Most vehicles now carry many different antennas for communications and they have a wealth of other electronic equipment that drives up the overall power consumption, boosting the demand for battery power.
“For military missions, vehicles require a lot of onboard power, from 40 to 90 kW to run all the accessories,” said Robert F. Combs, Director of Military Applications at Allison Transmission.
Providing that much power while also moving a vehicle along its route takes a lot of battery power. Most vehicle and battery suppliers feel that major improvements in battery technologies need to occur before plug-in electric vehicles can begin to compete at the same level as ICEs.
“Lithium-ion batteries aren’t yet completely ready for things like plug-in hybrids where you really utilize the battery’s full capabilities,” Jonsson said. “Developments in the commercial space can really help build up a knowledge base before we go into more demanding military markets.”
A key obstacle for hybrids and electric vehicles is their complexity. Most military technicians are unfamiliar with the many components added for electric powertrains, so significant amounts of training must occur before they can move into the mainstream for military vehicles.
Deploying hybrids in war zones also underscores the need to stockpile spare parts in addition to increasing training. That’s especially true as the U.S. exit strategy for Afghanistan proceeds and locals take over vehicle maintenance.
“We do our own maintenance, so adding a new technology can be very, very expensive in areas like Afghanistan,” said Lieutenant Colonel Graham Compton, the U.S. Army’s Product Director for Non-Standard Vehicles. “The literacy rate for Afghanis is around 20%; something as simple as filling out a requisition form won’t work there.
While very few other environments will have that limitation, product developers are always striving to simplify maintenance. In most military theaters, reducing downtime and the amount of training needed for each vehicle are important factors. That’s driving a trend toward plug-in componentry.
“Certainly a large degree of training needs to take place with hybrids,” said Gary Schmiedel, Executive Vice President of Technology at Oshkosh Corp. “It’s well within our capability to build products based on removing and replacing modules.”
At the same time, design teams are working to add features that help users and technicians understand what’s broken and how to fix it. They’re also working on prognostics, which will predict when failures may occur so preventive action can reduce overall downtime.
“Diagnostics and prognostics are becoming increasingly important,” Jonsson said. “Modularity is also very important.”
While electrified powertrains inch into military markets, developers are already looking at other alternative fuels. Some vendors feel that the shift to electric vehicles will help clear the pathway for a transition to hydrogen-based fuels.
“Fuel cells remain elusive,” Schmiedel said. “As we start embracing electrification, we can set the infrastructure for moving to fuel cells when the time is right.”