It sounds like something out of a science-fiction novel: e-bike batteries that can actually last as long as the e-bike does. But with to new cell technology, a battery life of more than 10 years may soon be possible. The new type of battery will also be capable of supplying much more power. Thanks to Tesla, all of this may well be achieved as soon as 2018.
Sony, Panasonic, LG, and Samsung produce approximately 80% of the world’s battery cells. Recent changes in these big four have directly led to Tesla’s backing of the revolutionized batteries for electric bicycles.
Battery cells are like the penlight batteries that used in just about all households. When many of these cylindrical cells are connected together, they make up an e-bike battery. A Battery Management System (BMS) does however have to be added to the cells to make the whole arrangement workable.
Previously, the big four cell makers supplied massive numbers of cylindrical cells to the IT industry. In recent years however, this industry has moved away from using cylindrical cells and toward using flat-form batteries in tablets, laptops and smartphones. Although a small percentage of the lost sales was recovered by batteries needed by Light Electric Vehicles and e-bikes, overall sales remained too small for Sony, Panasonic, LG, and Samsung to spend any money on the development of new cell technology.
Tesla changes the game
All of this changed dramatically when Tesla started placing huge orders for the “old” type cylindrical cells. Tesla’s newest Model 3 e-car in particular pushed the battery cell manufacturers to new highs. This e-car is very affordable, retailing at approximately $35,000 USD, but to achieve an extended range at smaller weight and dimensions, the new battery technology was required. At first, the battery cell manufacturers were able to add capacity to commonly used 18650 cells. Mo-Hua Yang, the GM of Taiwan-based battery manufacturer HiTech Energy, explained that two years ago such an 18650 cell battery had a 2.2Ah capacity. This has since been increased to 3.5Ah, but an even greater capacity is required for a new cell.
21700 cells in one battery
At the Eurobike show last September, new 21700 battery cell appeared on the horizon. It was not a featured attraction that caught everybody’s attention; the new batteries weren’t even on display. But it was mentioned in a press release from BMZ, Europe’s largest battery manufacturer. Sven Bauer, BMZ’s CEO, said in an interview with Bike Europe that this new cell will revolutionize electric bicycles. The 21700 cell battery will not only offer a much longer lifetime, but will have a much larger capacity for power and pedal-supported mileage.
BMZ is not the only battery manufacturer convinced of the extraordinary features the 21700 battery cell will bring to e-bikes. Taiwan-based HiTech Energy also believes the new cell will be the new standard in e-bike batteries.
The 21700 is a cell with a new format. Instead of an 18650 (18mm diameter, 65mm high) cell, the 21700 cell is 21mm diameter and 70mm high. This increase in size results in a larger output of up to 4.8Ah. With this capacity, the battery life is extended from the current approximate 500 charging cycles to up to 1,500 to 2,000 cycles. These increased charging cycles results in the longer lifetime as it’s recharging that ultimately kills batteries.
Yang noted that the same applies to e-bike batteries made with 21700 cells. He added that there’s also another much needed factor that comes into play. With rapidly increasing sales of electric mountain bikes, batteries that can offer more power and range are required. Yang concluded by saying that smaller batteries with 1,500 to 2,000 charging cycles and an output of 700Wh will be the new standard in 2018.