Battery
Lithium polymer packs refer to the way the pack is structured, using as a flat pack with multiple layers of the electrodes stacked with insulating film in between and covered in plastic foil. Cylindrical cells have a continuous foil of electrodes coiled and packed into a very thin steel casing.
18650 cells generally are rated at 3.6V and 2.2 Ah, so a pack with cells arranged 10 in series 3.6v x 10 = 36v and 5 of these in parallel would be 2.2 Ah x 5 = 11 Ah with some losses due to impedance in a series, the true capacity of a pack would be slightly lower. Each manufacturer of such cells have their own secrets to the chemical compositions and know-how, that’s where the differences lie.
The capacity of the battery is rated in Watts hours (Wh) which is the nominal voltage multiplied by the Amp hour (V x Ah).
(e.g. 36V x 10Ah = 360Wh). It is therefore essential to know both the V and Ah rating of a battery pack or the Wh directly.
Lithium batteries packs have a battery management system ( BMS ). It is an attached circuit board that performs the function of balancing the cells, short circuit protection, low voltage protection, over charging , limiting the maximum discharge current and temperature control.
Battery Safety
While Li+ cells from reputable brands have managed to make cells with a very high degree of stability, a high quality BMS is just as important to prevent short circuit and provide cell management. Our packs are fully tested to comply with safety standards written in UN38.3. Currently Li battery packs with the capacity exceeding 100 Wh is classified as Hazardous Material – Hazmat Class 9 , and would not be allowed on aircraft except on Cargo flights and have to be packed in carton approved with UN3841 ( Lithium battery with equipment ). UN 3841 is a simple procedure involving a drop test from a height of 1.2 meters with no resulting damages.