Lead–acid batteries for E-bicycles and E-scooters

Abstract There is already a huge market for electric low-power light traction vehicles, mainly electric two wheelers (E2W) in the forms of E-bicycles and E-scooters. Such vehicles satisfy the demand for low-cost personal and load transportation with a concomitant reduction of environmental pollution in comparison with the two-stroke powered alternatives. Worldwide E2W annual sales in 2015 reached about 38 million units, of which China accounted for 33 million. The range of E2Ws is limited and is determined mainly by the battery. Nickel–cadmium, nickel–metal hydride, lead–acid and lithium-ion batteries have all been tested, but the vast majority of E2W batteries are either lead–acid or lithium-ion. The lead–acid batteries (LABs) are primarily of the absorptive glass-mat (AGM) design, although some gel types are used. The lithium-ion batteries (LIBs) are lithium iron phosphate (LFP); nickel, cobalt and aluminium (NCA) or lithium manganese oxide (LMO) types. LIBs have a much higher specific energy and thus provide higher range, but they have markedly higher costs. The LIB advantage of larger range and/or lower weight has led to a nearly 100% penetration of the E2W market by LIB in developed countries (Europe, Japan and the US). In China, however, the market is dominated by about 90% by LABs. A future shift from LABs to LIBs seems improbable for the mass market, given the cost premium relative to the performance advantages of LIBs.