Lithium-Polymer Battery Backs Light-Weight System

March 31, 2010
Power systems for the Medium Armored Vehicle (MAV) must be robust, yet light in weight, often conflicting requirements in a battery pack. One supplier of MAV power systems, Falcon Electric, has developed a light-weight rechargeable ...

Power systems for the Medium Armored Vehicle (MAV) must be robust, yet light in weight, often conflicting requirements in a battery pack. One supplier of MAV power systems, Falcon Electric, has developed a light-weight rechargeable uninterruptible-power-supply (UPS) battery system based on lithium-ion-polymer technology, which is less than one-half the weight of comparably powered lead-acid battery solutions. The firm's ED-LIB series UPS power source delivers 3 to 5 kVA in a rugged, 4U rack-mount enclosure and is backed by a lithium-polymer battery that provides at least 2800 W backup power for 15 minutes in a 2U enclosure.

The ED-LIB series is actually a power system, with UPS frequency/phase converter in one 4U housing and lightweight battery pack (see figure) in a 2U enclosure. The battery pack, which includes lithium-ion cells, Advanced Battery Management System (ABMS), and charging circuitry, weighs only 55 lbs. The ABMS monitors each of the lithium-polymer cells and provides full cell equalization and overload protection. The 2U module's internal model EDBR50000-3/1/LI-SEC battery charger accepts three-phase inputs from 47 to 450 Hz and 115/200 VAC or single-phase power at 47 to 450 Hz and 115 or 120 VAC. For a linear load of 3500 W, the battery has a rated run time of 15 min.

The frequency/phase converter is also packed with power/voltage conditioning circuitry, in a housing measuring only 6.97 x 16.87 x 21.19 in. and weighing about 74 lbs. Specifically designed to work with the compact lithium-polymer battery pack, it converts incoming three-phase power from a utility or generator to direct current (DC) power which is regulated and processed by a pulse-widthmodulated (PWM) MOSFET inverter, which regenerates regulated, singlephase 120-VAC power at 50, 60, or 400 Hz. A power factor correction (PFC) of better than 0.9 pF is applied to input power. The ED-LIB System permits the connection of single-phase equipment to a three-phase source while maintaining balanced power draw from all three sources. This minimizes phase imbalances and harmonics and results in clean power for sensitive devices, including computers.

In an application such as the MAV, lead-acid batteries were not an option because of their weight. The MAV is designed to be air transportable in a C-130 aircraft, with a deployment weight not exceeding about 19 tons, which translates to a maximum transport distance in a C-130 of about 1000 miles. The ED-LIB series frequency/phase converter and lithiumpolymer battery power systems represented an ideal solution for the MAV, as well as for use with aircraft. Vehicle, aircraft, and ground-based generators tend to exhibit power instability, with sags, surges, and transients. The ED-LIB series sources can handle three-phase inputs of 120 and 208 VAC over a frequency range of 47 to 450 Hz and provide outputs at 120 VAC with 3 percent voltage regulation and less than 3 percent sinewave harmonic distortion. The system delivers outputs to 3200 W power, with 40 A average current and 100 A short-term peak current.

The system includes light-emitting-diode (LED) indicators to provide information on load level and battery level, inverter on, and utility or generator power present. Audible alarms warn of overloads, inverter failure, and interruptions in utility or generator power. Forced air fans provide cooling, with audible noise held to 54 dBA at 1.5 m. The ED-LIB series UPS and battery system is designed to operate from -20 to +50C, with short-circuit and overload output protection applying across the full operating temperature range. Three models are currently available in the ED-LIB series, with nominal ratings of 3000, 4000, and 5000 VA.

Falcon Electric, Inc., 5106 Azusa Canyon Rd., Irwindale, CA 91706; (800) 842-6940, FAX: (626) 962-7720, Internet:

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