Batteries that Stop Bullets

A Raytheon team has developed vehicle armor that doubles as a battery – a breakthrough that could power electronics, reduce engine run times and lessen the military's demand for costly, dangerous fuel convoys. The armor, described in a U.S. patent, works by layering bullet-resistant electrical conductors such as high-hardened steel with sturdy insulators such as ceramics. The result: Power goes through it. Bullets do not.

"My department manager, when he saw it, said, ‘Wow. Batteries that stop bullets,’” said Gary Wahlquist, one of the engineers named in the patent. The batteries store the energy that vehicles generate while in motion. When the vehicles are stopped, the crew can switch to battery power, rather than having to run the engine just to power their on-board electronics.

But how does it stand up as armor? Pretty well, Wahlquist said. During a ballistics test, a prototype stopped a 7.62 mm sniper-rifle round. If a round penetrates the battery, only the damaged cell will stop working; the others will continue supplying power.

The team's research is among many ways Raytheon is working to improve the storage, control and management of power, including a microgrid for the U.S. Marine Corps Air Station Miramar, and energy storage systems that can stash away power from renewable sources. The battery armor patent comes as the U.S. Department of Defense invests billions in energy-saving initiatives, spurred in part by deadly attacks on fuel convoys in battle.

More than 3,000 Army personnel and contractors were wounded or killed in attacks on fuel and water resupply convoys between the fiscal years 2003 and 2007, according to a summary of the defense department’s energy strategy. That same report said ground convoys were attacked at least 1,100 times in 2010.

Wahlquist and his colleagues started work on the invention several years ago, after hearing a speech about the hazards posed by the military’s need for electricity. Radios, high-tech sensors and other equipment require soldiers to lug around an estimated 10 pounds of batteries in addition to armor and a rucksack. The electronics also force military vehicles to keep engines running and carry fuel-guzzling generators.

While the patent application mentions ground troops – it even includes an “Iron Man”-esque drawing of a soldier decked out in the specialized armor – the team says its focus is on protecting and powering vehicles. The team’s goal is to allow armored vehicles more time in a state known as “silent watch,” where the engine is off but on-board optics and the gun turret remain powered. Just like a car, using electronics with the engine off drains the battery, often forcing soldiers to start the engine in the middle of the night – and give away their position to nearby enemy fighters.

“If you’re in a desert environment at night, and you have a Bradley or an Abrams tank with the engine on, you can hear them from long distances away,” said Chuck Betack, a retired U.S. Army colonel and Iraq War veteran who now works in Raytheon’s Integrated Defense Systems business. “It just seems to magnify the sound. You become a target.”

Betack, who advised the team throughout research and development, praised the engineers for their idea and their determination to see it through. “They did work on their own to get this thing to be functional,” Betack said. “It goes to show you how dedicated they are to helping find solutions that make a difference.”