Battery Pack

The key to developing a high-performance unmanned aerial vehicle: 
Custom made Li-ion battery packs!

Medium-altitude, long-endurance UAS/UAV/RPAS have been proven to be useful and cost effective, in both civilian and military applications. Equipped with powerful and durable batteries, they can handle all the challenges. 

cmec raw battery packs
CMEC raw battery packs

Creative Commons License This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.


 

Precise Handcrafting | In-house Assembly 

Each part is separately created, then all the sub-assembly are joined together to create a battery pack.

Wiring-harnesses in-house assembled - CMEC

CMEC raw materials

Adding matching cells and to engineer the battery packs. To minimize the variability inside a battery pack and to ensure maximize quality, all the cells need to have the same weight (margins of 0.001 grams), identical voltage rated, same rank and initial charging date, from the same manufacturing batch.

CMEC battery cells control techniques
Panasonic Sanyo NCR18650GA | Left: cell weight | Right: factory SoC state

For a more compact design, translated into more energy density per unit volume and to improve mechanical and thermal performance, the battery cells are joined in “honeycomb form”. On last battery pack update in November 2017, a thin aluminum conductive band, which flow to the outer, was inserted between cell rows Kapton coated. This cooling technology relies on the thermodynamics of conduction and it is used to complete the heat transfer process generated during high-discharge rates of battery cells. Using a hot-melt adhesive based on thermally-conductive polyamide (PA) copolymer with great bond strength, the “brick” are finally fully sealed. The upper part of cell are over-insulated with a ring-shaped dielectric material, then the cell’s terminals are joined by (99.97%) pure nickel-strips layers through (RSW) resistance spot welding, according to the serial/parallel configuration covet.

cmec-manufacturing-uavbattery

The wiring-harnesses for PCB/BMS, high quality polarized gold-plated connectors, and custom shielded discharge cables are applied, spending the more attention to detail and safety elements.

The entire cell block/brick is surrounded by a multi-layers shield with mechanical strength and dielectric insulated, outside-reinforced with a extra-thin Aluminium/Kapton® laminated film used also in the spacecraft industry. All covering & protection materials provide a high sealing, and contribute to the robustness of the battery pack.

CMEC UAV Battery

To reduce manufacturing costs, the pack is wrapped with a hard (Black & Blue) PVC film. With this kind of covering the aesthetic appearance isn’t charming, but looks very compact and solid. However, we work hard to develop a tough and lightweight battery housing, from composite materials.

6S6P 22.2V 60A NCR18650GA battery pack

drone battery

 


 

Design Safety Features: Cell Level

NCR cylindrical lithium-ion battery cells used in assembling of the CMEC battery packs hold an internal positive temperature coefficient (PTC) current limiting device. The initial function of this PTC is to limit short circuit current on an individual cell level. It is prime to note that this device is thoroughly passive and functions without any inputs from the rest of the battery pack systems.
A second level of protection is provided by the Current Interrupt Device (CID). Each battery cell used in the CMEC battery packs has an internal CID. This serve to protect the cell from excessive internal pressure.

About Panasonic: Producing a top-quality Li-ion cells require high-level production processes, high-precision machining processes and carefully selected material specifications. Parts of a high-class quality management system, based on Kaizen basic principles.

Panasonic NCR18650
Photos courtesy of Panasonic

 


 

Upcoming in 2018 | Ultimate manufacturability 

CMIUTA Electric Company will use 3D printing technology to manufacture a honeycomb-type battery cell holder from composite materials, for ultimate cooling efficiency, safeties and reliability. 8 hours it is average print time to mold a complete battery cell holder, including the covering parts. We still in the testing phase. Learn more >>>

Composite fiber cell holder - 3D Rendering by CMEC
Composite fiber cell holder – 3D Rendering by Cristian Miuta

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