Americans purchase nearly 3 billion batteries (dry-cells) every year. On average, each person in the US disposes of 8 batteries every year. The rate of battery use is sometimes even higher in military operations. During Operation Iraqi Freedom, the Marines used more than 3000 single-use batteries per day. A rechargeable battery can replace hundreds of single-use batteries over its life. Also, all batteries contain metals such as mercury, lead, cadmium, nickel and lithium, which may contaminate the environment if disposed of improperly. Hence reducing consumption is imperative to ease the strain on natural resources.
Apart from the issue of increasing efficiency, and reducing cost and wastage, rechargeable batteries are a key enabling technology for solving energy problems of the future. One key feature of renewable energy sources like solar, wind, tidal, etc. is that they are not continually available. A report by the California ISO Board says, "Wind generation energy production is extremely variable, and in California, it often produces its highest energy output when the demand for power is at a low point". An energy storage facility coupled with these power generation sources would make these solutions more economically viable. Such energy storages, comprising batteries, fuel cell or super-capacitors, would in turn need reliable health monitoring systems to ensure viable levels of system availability, reliability and sustainability and to protect the assets from degradation due to non-optimal usage.
Finally, battery health management will also play a critical role in electric vehicles that will be dependant on an accurate gauge for remaining charge and for trade-offs in long-term durability and short-term usage needs. A recent report by the Consumer Electronics Association, "Electric Vehicles: The Future of Driving", indicates that although these vehicles are increasing in popularity, running out of battery power on the road is the top concern for consumers.
The many benefits of electric propulsion are being applied to UAVs as well. An electric UAV has no exhaust noise and can temporarily minimize prop noise to tactical advantage. The control bandwidth available to the motor can be used to improve roll axis stability for sensing and targeting. Electric propulsion systems usually have lesser moving parts than conventional internal combustion engine (ICE) based systems, and hence are more reliable. Since for such aircrafts, the battery is the most critical element in the propulsion path, it is imperative to have some kind of battery health management system (BHMS) onboard.
Mars Global Surveyor
"The loss of the spacecraft was the result of a series of events linked to a computer error made five months before the likely battery failure," said board Chairperson Dolly Perkins, deputy director-technical of NASA Goddard Space Flight Center, Greenbelt, MD.
On Nov. 2, after the spacecraft was ordered to perform a routine adjustment of its solar panels, the spacecraft reported a series of alarms, but indicated that it had stabilized. That was its final transmission. Subsequently, the spacecraft reoriented to an angle that exposed one of two batteries carried on the spacecraft to direct sunlight. This caused the battery to overheat and ultimately led to the depletion of both batteries. Incorrect antenna pointing prevented the orbiter from telling controllers its status, and its programmed safety response did not include making sure the spacecraft orientation was thermally safe.
(Courtesy: NASA NEWS RELEASE 2007-040 )
BEECH A200 (Reg # N258AG)