About Cells
Lead-acid: Traditionally, most EVs have used lead-acid batteries due to their mature technology, high availability, and low cost (exception: some early EVs, such as the Detroit Electric, used nickel-iron.) Like all batteries, these have an environmental impact through their construction, use, disposal or recycling. On the upside, vehicle battery recycling rates top 95% in the United States. Deep-cycle lead batteries are expensive and have a shorter life than the vehicle itself, typically needing replacement every 3 years. Lead-acid batteries in EV applications end up being a significant (25%-50%) portion of the final vehicle mass. Like all batteries, they have significantly lower energy density than petroleum fuels—in this case, 30-40Wh/kg. While the difference isn't as extreme as it first appears due to the lighter drive-train in an EV, even the best batteries tend to lead to higher masses when applied to vehicles with a normal range. The efficiency (70-75%) and storage capacity of the current generation of common deep cycle lead acid batteries decreases with lower temperatures, and diverting power to run a heating coil reduces efficiency and range by up to 40%[citation needed]. Recent advances in battery efficiency, capacity, materials, safety, toxicity and durability are likely to allow these superior characteristics to be applied in car-sized EVs. Charging and operation of batteries typically results in the emission of hydrogen, oxygen and sulfur, which are naturally occurring and normally harmless if properly vented. Early City car owners discovered that, if not vented properly, unpleasant sulfur smells would leak into the cabin immediately after charging. Lead-acid batteries have been re-engineered by Firefly Energy, increasing longevity, slightly increasing energy density, and significantly increasing power density. Firefly is expected market lightweight vehicle batteries, either directly or through manufacturing partners in 2008. Lead-acid batteries powered...
