In a 2011 SAE paper, a team from TARDEC noted that replacing lead-acid batteries military vehicle batteries with a Li-ion system would offer a number of benefits. These include doubling the reserve time of the stock battery and delivering a significantly greater number of charging and discharging cycles while also providing weight savings. Additionally, they noted, there is no acid inside a lithium ion battery to cause corrosion, which eliminates potential damage to a vehicle from chemical spills and poisonous gases. However, they also noted:

...the characteristics, including the charge and discharge control of lithium ion battery chemistries, are different from those of flooded and sealed lead acid batteries. The traditional continuous battery charging approach may potentially result in overcharge and thus raise safety concerns for lithium ion battery replacement. In addition, lithium ion batteries experience reduced battery service life when exposed to very low and deep discharge levels...Although lithium ion battery replacement may have value for vehicle applications that have strict weight and volume requirements, and a need for increased power, their higher cost, low temperature performance, and sophisticated controls may create challenges when they are used in place of traditional vehicle SLI lead acid batteries.

—Ding et al.

A123 Systems believes it has worked through those issues. Based on A123’s proprietary Nanophosphate lithium iron phosphate technology, the Military 6T Battery leverages the systems engineering and manufacturing design utilized to produce A123’s 12V Engine Start Battery (earlier post), which is currently offered to commercial automakers. The Military 6T Battery is offered in both a 12V and 24V model to accommodate specific vehicle requirements. Standard features and benefits of each of A123’s 6T battery models include:

• Longer Cycle and Calendar Life. A123’s Military 6T Battery systems are designed to perform significantly more depth of discharge cycles compared to other battery technologies. A123’s lithium iron phosphate military batteries also deliver superior calendar life, lasting significantly longer than the most advanced lead acid batteries. This reduces battery replacement costs, enables vehicles to operate for longer periods of time and reduces life-cycle cost.

• Greater Charge Acceptance Rate. A123’s lithium ion technology is capable of rapid charging, and it also delivers more power when the engine is off to facilitate longer-duration silent watch capabilities.

• Reduced Weight. A123’s Military 6T Battery is about 50% lighter than lead acid battery systems, offering significant weight savings for transport to the battlefield. This improves fuel economy and packing efficiency of the transport vehicle which allows for fewer trips into hostile areas.

• Intelligent Battery Management System. In addition to lithium iron phosphate cells, A123’s Military 6T Batteries are equipped with battery management electronics that help balance and safeguard the cells, in addition to providing built-in system level safety features for under/over voltage cutoff, overcharge and over-temperature protection. The battery management system also communicates diagnostics, state-of-charge information and current and voltage measurements during silent watch, maximizing the performance of the Military 6T Battery when operating communications, surveillance and other equipment while the vehicle’s engine is not running.

Alexander said that A123 has done ballistics testing as part of its safety testing.

There are three major phases of launching a military product, Alexander said: proof of concept and testing; vehicle qualification; and manufacturing. A123 is in the first phase, and prepared to enter the second.

Manufacturing sets us above the rest. We are already doing commercial batteries, we already have the factories in place. Our path to production is pretty smooth.

There is no doubt that we are not going to be the cost parity of lead-acid, but we are at least three times the life and only 3-4 times the cost, and costs come down. We are also half the weight. Weight is very important. Third, look at the functionality of what they want the battery to do. To improve the silent watch mission, turn off the vehicle, run the equipment for the appropriate period of time. You can do silent watch, and recharge the battery rapidly. Our value proposition is better life, improved functionality and longer rate.

At the end of the day, the military will get a highly reliable, highly manufactured product at good cost. They will not get a customized product with a cost premium—that’s where they’ve gotten into some trouble. They’ve developed specs around their needs, and paid a premium for the products. If we take a manufactured approach, looking at how we ruggedize our products for their needs, it’s a much easier proposition than looking at a clean sheet of paper and looking for a new chemistry.

—Les Alexander

There are nearly 800,000 6T batteries currently deployed in US military vehicles, Alexander said, and in 2010 alone, the military purchased about 300,000 6T batteries—virtually all of which were lead-acid.

The A123 6T has demonstrated the ability to start a High-Mobility Multipurpose Wheeled Vehicle (HMMWV), and the company has begun delivering 6T systems to a number of defense contractors so they can evaluate its performance as a first step toward potential high-volume production.

I think the 6T will help the commercial side. What the military provides is a platform to challenge the upper limits of the chemistry. You get a wider range of operating temperatures, a wider range of duty cycles to advance the commercial products.

—Les Alexander

A123 is showcasing its Military 6T Battery and other government and military solutions during the Association of the United States Army (AUSA) Winter Symposium. The 6T-12 and 6T-24 versions of A123’s advanced lithium iron phosphate military battery solution are available now, and pricing is available upon request.

Resources

• Ding, Y., Zanardelli, S., Skalny, D., and Toomey, L. (2011) Technical Challenges for Vehicle 14V/28V Lithium Ion Battery Replacement. (SAE Technical Paper 2011-01-1375) doi: 10.4271/2011-01-1375

• Technical Challenges for Vehicle 14V/28V Lithium Ion Battery Replacement (presentation)