It used to be that when you talked about car batteries, there was just one technology involved: Lead-Acid. Lead-acid batteries have been around for over 100 years but their days may be coming to an end. There are two reasons for this: first, lead-acid batteries contain a major environmental poison – lead! Even though there are recycling programs for lead-acid batteries, because so many are made every year it is inevitable that some of the lead gets into the environment. The second issue is that they simply don’t have enough power for electric car use. Fortunately, less hazardous and more powerful batteries are being made.
The Old Standard
Lead acid batteries are well known technology and are inexpensive to manufacture. Your standard lead-acid battery is a thick plastic box with a series of heavy lead plates inside. These plates are suspended in a mix of water and sulfuric acid. The way it all works is that when needed, current flows from the lead-oxide plates (called cathodes) to the pure lead plates (called anodes). Each individual set of anodes and cathodes can only generate 2.1 volts so a set of six is necessary to generate the voltage that cars and trucks need (12.6 volts.)
The biggest problem with lead-acid batteries, beside the environmental issues, is that they aren’t terribly good for “deep discharge” applications. They are perfect for the peak current needed to start internal combustion engines, but they aren’t good for continuous use. Unfortunately, that is exactly what electric cars need, batteries that can be used continuously until they are exhausted of power.
Another type of battery technology is called Nickel-Metal Hydride (Ni-MH). Do you remember the rechargeable Ni-Cd batteries of years ago? They were the state-of -the-art back then. The problem with Ni-Cd batteries was that they developed a “memory” after repeated charges and then wouldn’t deep charge anymore. Because of this problem, engineers developed a better type of rechargeable battery: the nickel-metal hydride (Ni-MH) battery. Ni-MH batteries have twice the energy density of Ni-Cd batteries and they don’t have memory effect. As a result, Ni-MH batteries have become a mainstay technology in rechargeable batteries today. Toyota and Honda employ NiMH battery technology in their hybrids.
In the continuous search for higher power density, Li-ion technology was developed. Li-ion batteries offer 11 times the power of Ni-MH. This is a major advancement for the electric car industry. One small disadvantage is that in electric car use, a full bank of Li-ion batteries requires its own cooling and heating system to maintain optimal operating temperatures. The question is: How do they perform? We asked friends of ours, Hiley VW of Arlington, a local VW dealer in Arlington, TX, and they told us that VWs first EV, the e-Golf utilizes a 134-hp 100-kWh electric motor powered by a 35.8-kWh lithium-ion battery. The EPA estimates 125 miles of range on a single charge; fuel economy is rated at a combined 119 MPGe. While these specifications are typical of the breed. The company allows that it is working on lithium-ion batteries of considerably higher energy density in an attempt to get the range over 200 miles.
Earthgarage – Greener Car. Fatter Wallet.