Lux sets sights on replacing nicad batteries with lithium

 - September 22, 2008, 11:37 AM

Lithium batteries, as used in cellphones, laptops and other electronic equipment, have been in the news recently, as airlines have severely limited their carriage on aircraft due to the hazard of fire. So it might not seem an opportune time to begin marketing a lithium battery designed to replace nicad and lead-acid aircraft batteries.

Despite lithium batteries’ ability to make headlines, Gulfstream has chosen Lux Aviation Engineering to provide four separate lithium batteries for various essential applications on the new G650.

The Tucson, Ariz. company’s ElectroBatt line is designed to replace lead acid and nicad batteries on aircraft. It includes engine start and emergency backup applications.

CEO Dick Lukso said, “We’ve been working with the concept of lithium batteries in aircraft for about four years,” he said. “We feel lithium batteries are the future, but if it were an easy technology they would already be in aircraft.”

He noted that with a conventional lead- acid or nicad battery “what you see is what you get. The electrochemistry is the battery. With lithium, the actual electrochemistry of the cells represents about half of the content and cost of the battery.” His lithium battery includes an integrated charger and safety circuitry.
“Lithium has some serious safety concerns, including a potential fire hazard, if not properly protected. We’ve spent nearly $2 million on protection circuitry so we can closely monitor the battery,” said Lukso.

He said the electronic aspect of the battery is so crucial to the system that it took an electronics company to design and develop it. The company has a crucial combination of experience and expertise, according to Lukso. “We’ve built lead- acid batteries and chargers, and were involved with writing the RTCA DO-311 test guidelines for lithium rechargeable batteries for aircraft.

“This has a diagnostic system unlike any previous battery technology. We can determine, and display to the pilot, an accurate state of charge within about two percent,” he said. “The battery can interface with an eicas, link to the aircraft central maintenance computer and becomes part of the go/no-go system,” he added.

The system looks in real time at a number of parameters such as over-voltage, over-current and over-temperature.

It monitors the parameters for the battery as a whole but also for each individual
cell and the electronic system itself. “The system also uses parallel charging/control of each of the lithium cells for the utmost in safety,” he said.

“In the highly unlikely event all that fails, we also have an organic sniffer device that monitors the electrolytes,” he said. “The sniffer ultimately gets it down to one chance in 10 billion that a catastrophic failure will result in a fire.”

With a system in place that makes a lithium battery safe for use in an aircraft, the benefits become compelling.

“This battery will reduce maintenance to nothing,” Lukso explained. “If someone leaves a light on and runs down a regular battery, you’re out of luck. It has to be removed and serviced. With this battery in that situation, depending upon the OEM’s specifications, it will automatically shut down somewhere between 18 and 21 volts. Therefore, the battery does not have to be removed from the aircraft and undergo maintenance. You can just hook up a GPU and recharge it. By the time we cut the battery off there are only seconds of useable power remaining; however, it is sufficient to maintain the health of the battery and allow it to recharge.”

The company anticipates that the new battery will have a five-year life expectancy versus the approximately two-year expectancy for most lead-acid batteries.

According to the company, the battery has about half the weight of existing lead-acid and nicad batteries and can be approximately 40 percent of the size of the equivalent current technologies. Lux Aviation is developing a 63-amp/hour battery that weighs 45 pounds and is designed to replace a 40-50 amp nicad or lead-acid battery that would weigh about 90 pounds. A 30-pound, 40-amp/hour version is also in the works.

The company is aiming to have a production battery available by year-end. The 32-amp/hour version is expected to cost approximately $7,500 for a retrofit. The new battery includes a charger and–in addition to replacing the original battery– replaces other LRUs, resulting in a significant overall weight reduction.

“When installed as original equipment it provides even better weight savings,” he said. “On the G650 it will be approximately 200 pounds [lighter than] equivalent lead- acid or nicad batteries, the weight equivalent of one passenger or 30 gallons of fuel.”