308
Alternative Fuels for Transportation
The electric passenger vehicles being tested today operate mostly on the
lead–acid system and will remain dominant in the near-term. The major
advantages of a lead–acid battery include low cost, mature technology, and
relative high power capability. The performance of present EVs is limited
mainly by the low-energy density of the lead–acid battery. The other drawbacks are slow recharging time, the need for careful maintenance, and poor
performance under cold climates where the temperature gets less than 10°C.
Modern technologies enable the use of lead–acid batteries without these
major drawbacks, but of course, with an increase in cost.
Lead–acid batteries constructed with tubular positive electrodes, give a
significant improvement in life. A lifetime can be obtained as much as 5
years under well controlled charge and discharge conditions. Gassing during charging produces hydrogen that requires venting to the atmosphere and
in most vehicle installations positive extraction is used to avoid the buildup
of a potentially explosive gas mixture.
Advanced lead–acid battery technologies offer improved retention of
positive plate material during high discharge operations. This includes an
increase in maximum energy density from 35 to 45 Wh/kg and a substantial
improvement in maximum power capacity from 150 to 250 W/kg.
In sealed bipolar technology, the electrical resistance of the lead grids and
the connectors between them is minimized by the use of a conducting plastic in the cell wall that permits low loss transmission of current while maintaining the seal between the cells.
The major breakthrough came with valve regulated lead acid (VRLA)
batteries that allow fast charging typically 50% in 5 minutes and 80% in 15
minutes. This is done using computers to control the charging rate while
monitoring the battery temperature and internal resistance. These batteries
have pressure relief valves, which will activate when the battery is recharged
with high voltage. The charging characteristics of a typical VRLA battery
charged to an interactive pulsed current/constant voltage algorithm are one
second bursts of high current with a ten millisecond pause between each
pulse to measure internal resistance.
10.3.2.4 Nickel-Based Batteries
Nickel is a lighter metal than lead and has very good electrochemical properties desirable for battery applications. The different types of nickel-based
battery technologies include nickel–iron, nickel–zinc, nickel–cadmium, and
nickel-metal hydride.
10.3.2.4.1 Nickel–Iron
This battery uses nickel as the positive electrode and iron as the negative.
Usually potassium hydroxide is used as an electrolyte. The self discharge of
these batteries are high and eventually this problem is reduced by adding
Alternative Fuels for Transportation
The electric passenger vehicles being tested today operate mostly on the
lead–acid system and will remain dominant in the near-term. The major
advantages of a lead–acid battery include low cost, mature technology, and
relative high power capability. The performance of present EVs is limited
mainly by the low-energy density of the lead–acid battery. The other drawbacks are slow recharging time, the need for careful maintenance, and poor
performance under cold climates where the temperature gets less than 10°C.
Modern technologies enable the use of lead–acid batteries without these
major drawbacks, but of course, with an increase in cost.
Lead–acid batteries constructed with tubular positive electrodes, give a
significant improvement in life. A lifetime can be obtained as much as 5
years under well controlled charge and discharge conditions. Gassing during charging produces hydrogen that requires venting to the atmosphere and
in most vehicle installations positive extraction is used to avoid the buildup
of a potentially explosive gas mixture.
Advanced lead–acid battery technologies offer improved retention of
positive plate material during high discharge operations. This includes an
increase in maximum energy density from 35 to 45 Wh/kg and a substantial
improvement in maximum power capacity from 150 to 250 W/kg.
In sealed bipolar technology, the electrical resistance of the lead grids and
the connectors between them is minimized by the use of a conducting plastic in the cell wall that permits low loss transmission of current while maintaining the seal between the cells.
The major breakthrough came with valve regulated lead acid (VRLA)
batteries that allow fast charging typically 50% in 5 minutes and 80% in 15
minutes. This is done using computers to control the charging rate while
monitoring the battery temperature and internal resistance. These batteries
have pressure relief valves, which will activate when the battery is recharged
with high voltage. The charging characteristics of a typical VRLA battery
charged to an interactive pulsed current/constant voltage algorithm are one
second bursts of high current with a ten millisecond pause between each
pulse to measure internal resistance.
10.3.2.4 Nickel-Based Batteries
Nickel is a lighter metal than lead and has very good electrochemical properties desirable for battery applications. The different types of nickel-based
battery technologies include nickel–iron, nickel–zinc, nickel–cadmium, and
nickel-metal hydride.
10.3.2.4.1 Nickel–Iron
This battery uses nickel as the positive electrode and iron as the negative.
Usually potassium hydroxide is used as an electrolyte. The self discharge of
these batteries are high and eventually this problem is reduced by adding