In a new generation of warfare, today’s military vehicles will be tasked to, in effect, function as mobile power plants. That is forcing electronics designers to reevaluate the power architecture, and how a vehicle’s emerging sensors and communication systems are powered on-board. Specifically, they’re taking a look at – and questioning the effectiveness of – legacy Pb-acid (lead-acid) 6T batteries.
Previously, military vehicles only required enough power to support radios and electronic systems that could be operated for short time periods without starting the engine. However, today’s vehicles feature sensors, jammers, communication, and control systems. More complex vehicles require higher power and more energy than Pb-acid chemistry can provide. The ability to generate significant amounts of electrical power is critical for the full technology spectrum of modern industrial, tactical, combat, and hybrid vehicles.
The NATO 6T battery format, the most common battery used in military vehicles around the world, is often comprised of 28VDC batteries with two 12VDC lead-acid batteries strung in series for ground vehicles. The batteries were originally used for just starting, lighting and ignition (SLI) loads, but as the complexity of vehicle integrated systems increased, the vehicle batteries were also used to provide higher power loads and cycled at up to 80 percent depth of discharge.
The increased strain on lead-acid 6T batteries causespremature failure by excessive discharge, improper charging, and extreme internal temperatures. In turn, military operators must frequently stock and replace the batteries, resulting in limited trust by troops during deep-cycle applications. Another shortfall is that State of Charge (SOC)/State of Health (SOH) is difficult to detect, which could cause unexpected power loss, leading to engine start failures, inability to complete missions, and increased danger for soldiers.
The good news is that advances in lithium-ion battery technology have created new opportunities for the development of innovative power solutions capable of pushing outdated legacy technology and chemistry aside, allowing engineers to explore new possibilities with their on-board designs.
Li-ion technology offers many benefits over lead-acid, such as longer life, lighter weight, higher energy density, and lower total cost of ownership. Substantially longer battery life significantly enhances the capabilities of today’s military vehicles, supporting extended silent watch operations (engine off mode), and a multitude of technologies on the vehicle that run on battery power. What may be most encouraging related to adapting existing vehicles to Li-ion, is a drop-in replacement component that many Li-ion batteries feature.
One Li-ion battery provides the power equivalent of two lead-acid batteries at a quarter of the weight and half the volume with greater power and energy density.
In addition to the enhanced performance benefits, Li-ion power systems have proven successful in reducing the total cost of ownership for military vehicles. Li-ion battery packs reduce logistical burdens to stow, transport and distribute replacement batteries. This translates to over $200 million of potential savings in total cost of ownership for a fleet of 20,000 vehicles over a 20-year life. With a market size of 700,000 lead-acid batteries acquired per year by the military, the widespread adoption of Li-ion technology can return tremendous cost savings to the end user.
At the same time, size and scale of the U.S. military marketplace and the prospect of an across-the-board transition to a new battery class has represented a challenge. Until now, production costs have limited the availability and wholesale integration of the superior Li-ion systems. But that is changing.
The cost-efficient mass production of Li-ion batteries
will mark a sea-change in the performance, reliability and safety of modern military ground vehicles. Along with advanced performance, logistical costs will be significantly reduced. Engineers are welcoming the arrival of this new battery technology, as are the military and service personnel it is designed to protect.
