How 6 pounds of power makes a big difference
Already burdened with plenty of equipment, dismounted soldiers might get to trim some of the weight of heavy batteries
Although more capable equipment and communications will provide a substantial tactical edge for the dismounted soldier, the inescapable fact is that all of this equipment must be powered. And the more you want to do with that equipment, and the more images and data you want to deliver through it, the greater the need for power.
The goal is not to have that situation add to the heavy load soldiers already carry. The decade-old Land Warrior kit that is being replaced by Nett Warrior required more than 13 watts per hour to power it, which meant that every soldier must carry three 2.2 pound batteries each day. The total weight of the entire Land Warrior ensemble is 18 pounds.
The goal for Nett Warrior is to reduce battery needs to just two a day, and to have the total weight come in at no more than 12 pounds. The use of technology such as smart phones will help with that, but squeezing more out of battery technology will be crucial to meeting the kind of power-to-weight trade off goals the new gear requires.
It’s a constant grind for power technology companies in trying to meet the criteria for this, said Jeffrey VanZwol, vice president of marketing for Micro Power Electronics, Inc., which provides custom battery systems for military OEMs and other markets.
“There is always the push with every customer for handheld devices to use more power in a smaller footprint, and that is even more exaggerated in the case of the dismounted soldier because he is already carrying so many devices with batteries integrated with them, as well as replacement batteries,” he said.
The standard military battery in the past provided a continuous supply of 2.6Ah (amp hours), he pointed out, but the typical military OEM now uses higher capacity batteries that run at 3Ah, and battery cells that can run at 4Ah are already on the drawing board.
There are several ways to get around the power-to-weight conundrum. One is to lighten the packaging of the battery. The typical military battery uses a metal can enclosure, but new battery packs using much lighter lithium polymer materials are now being pushed into the field after achieving a mil standard rating during the past year.
In this battery, the cell itself is made out of a coffee-bag type of material, VanZwol said, which is flexible so you can get the shape of the cells to be custom fitted to the battery package. That means you can maximize the amount of active material in the battery, which in turn makes for more battery runtime.
Another option is to use a different material with better performance characteristics for the battery cells. The predominant chemistry in both notebook and cell phone batteries now is lithium cobalt dioxide, more commonly referred to as lithium ion. A newer technology that’s being introduced in military batteries uses lithium iron phosphate, which is based on the same chemistry as lithium ion, but which has a somewhat greater discharge current and longer life.
But its greatest advantage for the dismounted soldier is a much faster recharge rate. A lithium ion battery typically takes two to three hours to fully recharge, whereas you can drop a lithium iron phosphate battery into a charger and have it recharged in as little as 15 to 30 minutes, VanZwol said.
However, finding a way to recharge batteries is a constant headache for soldiers in battle, and it’s another area that’s seeing potentially big advances.
“Short of coming up with a nano cold fusion reactor that’s cheap enough to put onto every soldier, finding a better way to recharge batteries is crucial” to enable the vision of the connected dismounted soldier, said Joe Taylor, vice president of ground combat systems at Northrop Grumman. “You can’t carry enough batteries into combat for multiple day operations without the ability to recharge them.”
One answer could be the kind of development Northrop Grumman is partnering with BAE Systems on to turn the future Ground Combat Vehicle (GCV), which will carry the dismounted soldier into battle, into what Taylor described as a “power export capable node” on the battlefield.
Under their proposal, the vehicle will use a hybrid electric drive propulsion system that will have huge reserves of power left over after its primary use that can then be stored in large batteries which would be an integral part of the GCV design. Dismounted soldiers would then simply drop their smart phones and radio batteries into recharge jacks built into the GCV.
Another possibility is to use battlefield robots such as Northrop’s Carry-All Mechanized Equipment Landrover, which is also in development. That’s slated as a an overall squad support robot, but one of its responsibilities could be to act as a charging device for batteries. Other companies have similar robot platforms in development.
These kinds of solutions could be available relatively soon, Taylor said. The GCV is a seven-year program from initial development to production, though that’s still fast compared to previous technology development cycles. The squad support robot could be on the battlefield much sooner, depending on requirements and budgets, Taylor said.