CNHL (China Hobby Line) Long Range Series 10000mAh 21.6V 6S 21700 Li-ion

The CNHL Long Range 10000mAh 6S2P is a lithium-ion pack from CNHL (China Hobby Line) for mid-size multicopters built for range and endurance. It consists of twelve BAK cylindrical cells in the 21700 format: six series stages with two cells in parallel each, 10,000 mAh in total.

A nominal 21.6 V and 10 Ah give 216 Wh; at 852 g that is about 254 Wh/kg at pack level, calculated on the finished pack. Li-ion cells of this kind are built for energy: there is no uniform C figure, and the permitted continuous current of the pack is the cell value multiplied by the number of parallel strings, here two. The connector is an XT60; the pack is also offered with an XT90.

216 Wh is above the 160 Wh limit of the IATA passenger leaflet (February 2019 edition): the pack travels only as dangerous-goods cargo, not as a spare in hand baggage. Every shipment requires UN 38.3 testing; the current edition and the airline's rules should be checked before travel. The 852 g count towards the take-off mass on which the EU classes C0 to C4 are drawn.

In selection the capacity matters less than whether the hover current of the aircraft stays below the cell continuous current times two. Cylindrical cells in metal cans do not show ageing by swelling, but by falling capacity, heat under load and group voltages that drift apart at the seven-pin balance lead. In the cold the current capability of Li-ion drops markedly. The connectors between the cells are delicate, so the pack should not be knocked or squeezed.