BEI Maximus UL 20A Battery | 14S1P 54.04V 21.1Ah High-Energy Density UAV Pack

The BEI Maximus UL 20A 14S1P Battery Pack is an ultra-high-energy battery system designed for UAVs, aerospace platforms, robotics, and other weight-critical applications where maximizing stored energy while minimizing battery mass is essential.

Built using BEI’s Maximus UL 20A lithium-metal cells, the pack combines a 519 Wh/kg cell-level gravimetric energy density with high discharge capability and excellent low-temperature performance. The 14S1P configuration provides up to 21.1 Ah typical capacity and 1,141 Wh of energy, making it particularly well suited for long-endurance aircraft and high-energy aerospace applications.

Cell Datasheet

BEI specifies operation down to −35°C, with the cells capable of up to 8C continuous discharge at −20°C. This combination of energy density, power capability, and low-temperature operation makes the Maximus UL platform particularly attractive for aircraft where battery mass directly affects endurance, payload capacity, and overall system performance.

 

Technical Specifications

Configuration: 14S1P
Nominal Voltage: 54.04 V
Maximum Charge Voltage: 60.2 V
Discharge Cutoff Voltage: 42.0 V

Capacity

Typical: 21.1 Ah @ 0.1C
Minimum: 20.0 Ah @ 0.1C
Rated: 19.6 Ah @ 1C

Energy

Typical: 1,141 Wh @ 0.1C
Minimum: 1,081 Wh @ 0.1C
Rated: 1,053 Wh @ 1C

Charge Current

Standard: 4 A (0.2C)
Maximum: 20 A (1C)

Discharge Current

Standard: 20 A (1C)
Maximum Continuous: 100 A (5C)
Maximum Continuous @ −20°C: 160 A (8C)
Maximum Discharge ≤300 sec: 200 A (10C)
Maximum Pulse ≤10 sec: TBD by BEI

Internal Resistance

Cell ACIR: ≤1.6 mΩ @ 1 kHz, 30% SOC
Cell DCIR: ≤4.0 mΩ @ 30% SOC

Pack-level resistance varies with interconnects, wiring, connectors, and final configuration.

Environmental Specifications

Charge Temperature: +10°C to +45°C
Discharge Temperature: −35°C to +71°C
Storage Temperature: 0°C to +45°C
Maximum Cell Body Temperature: 90°C

Mechanical Specifications

Cell Weight: 157 g each
Cell-Level Mass (14 cells): ~2.20 kg
Finished Pack Weight: Dependent on final construction, wiring, connector, protection, and enclosure requirements

Cell Performance

Cell-Level Gravimetric Energy Density: 519 Wh/kg @ 0.1C
Cell-Level Volumetric Energy Density: 1,282 Wh/L @ 0.1C

Cycle Life:
70 cycles — 0.2C charge / 1C discharge, 100% DOD to 80% SOH
30 cycles — 1C charge / 2C discharge, 100% DOD to 80% SOH

Cell Certification: UN 38.3

BEI Maximus UL 20A Datasheet.pdf

Availability

Lead Time: Approximately 3 weeks

BEI Maximus UL 20A cells are currently intended for testing and evaluation applications, with availability subject to supply. Custom pack configurations, connectors, wiring, BMS integration, mechanical packaging, and system-level engineering are available through Zero Point Energy Labs.

BEI Maximus UL 20A Datasheet.pdf

For full technical documentation, integration support, or custom battery configurations, please contact our team.