As for most electric bikes and trikes today, VELOKS make use of Lithium cells in its batteries. Today, there are only a handful of Lithium cells producers, key ones are Panasonic, Samsung, LG, SONY and SANYO. Most other brands are based on OEM versions produced by these manufacturers.
Lithium cells comes in many shapes and sizes, but most common for electric bikes are the cylinder shaped 18650 cell and more rarely the cylinder shaped 21700 cell. The first two digits refer to the diameter (18 mm and 21 mm respective, while the 3 last digits refer to the height (65mm and 70 mm respectively).
Each of these types of cells has a nominal voltage of 3.7 volt, while the energy (expressed in Ah = amperage per hour) varies depending on chemistry and size. Similarly, the continuous maximal discharge current and maximal change current will vary deepening upon chemistry and size. Cell types that VELOKS uses or have used are:
|Type||Voltage||Capacity [Ah]||Discharge Current [A]||Charge Current [A]||Charge Cycles [80%]||Density [W/Kg]
|Samsung INR21700-50E ||3,7||5||10||2,5||500||272
Critical criteria for selecting these cell types were: capacity (>=2.9Ah), energy density (>= 240 W/Kg), price, quality manufacturer, availability, charge current (>= 0.5C), discharge current (>= 10A), and charge cycles (>=500).
VELOKS is producing its batteries in house from scratch, this allows us to make use of the best battery cells on the market, and make quick changes as the technology evolves.
When we started in 2015, we used Panasonic NCR18650PF, as these were and are very good cells for the price. Following that we switched to LG INR18650MH1, which are similar in price, but has more capacity. Since spring 2019, we have used the INR18650-35E and INR21700-50E cells from Samsung, as these now are priced reasonable, and have higher capacity. Lately we have added high current cells in order to support our new 4000w and 6000w MK3 models.