The Dirty Little Secret about Electric Vehicles

Electric Vehicles have gotten a lot of media attention over the last few years. The United States, with the rest of the developed world, have made a push to reduce emissions and improve air quality in our cities. We use things like O2 sensors and Air Fuel Ratio sensors, along with catalytic converters, in order to reduce the impact that gasoline engines have on the environment. Recently, companies have been exploring ways to abandon gasoline consumption all together and produce “zero emissions” vehicles in the form of electric vehicles, like the Nissan Leaf. Although people have thoughtfully explored the impact of producing the electricity needed to charge the battery, all of the green-enthusiasts are conveniently looking away from the real issue: the lithium ion battery itself.

Nissan Leaf

 Lithium is a soft, silver-white alkali metal with the symbol Li on the periodic table. It does not occur freely in nature; it only appears in compounds that are usually ionic. Lithium salts are extracted from the water of mineral springs, brine pools, and brine deposits. The metal is then produced via electrolysis from a mixture of fused lithium chloride and potassium chloride.

The brine is usually pumped to large pools to let the sun evaporate the salts to a high enough concentration. Then this potent solution is pumped onto trucks and driven to processing facilities. Currently, 61% of the world’s lithium production occurs in Chile. Worldwide reserves of lithium are estimated at about 13 million tonnes. Using the battery efficiency figure of 400 g of lithium per kWh, this gives a total maximum lithium battery capacity of 52 billion kWh which, assuming it’s used exclusively for car batteries, is enough for 2 billion cars with the same size battery as a Nissan Leaf.

Lithium brine pools

 Problem is, only 25% of the world’s lithium goes into the manufacture of batteries (and that includes batteries for laptops and cell phones).  Lithium is used for processing silica to make glass, as a major component in high temperature grease, in air purification systems, in nuclear weapons, and even in pharmaceutical drugs to treat bi-polar disorder. The world’s supply of lithium would be exhausted relatively quickly if we tried to run most of the world’s vehicles on lithium-ion batteries.

In response to this claim, many bring up the fact that Lithium batteries can be recycled, and thus diminishing the problem of depleting this rare metal. The problem with this is that lithium is rather volatile at room temperature, so the entire battery has to be cooled down to -345°F before it can be dismantled and recycled. Cooling batteries down to such extreme temperatures uses a tremendous amount of energy, reducing the favorable environmental impact lithium ion batteries are supposed to have.

In reality, with a rapidly expanding population and ballooning consumption of energy worldwide, there is no magic solution to solve our emissions problems and save the world. Continuing current habits of every individual driving and using inefficient means of transportation, along with the host of other issues with consumer culture, leaves little doubt that our current style of living is unsustainable. Save for the unlikely invention of cold fusion, we are going to have to re-evaluate the way in which we travel.

What is MPGe?

Greater environmental protection measures have led to a push for more fuel efficient vehicles. Along with the development of catalytic converters, air fuel ratio sensors, and O2 sensors for standard gasoline engines, automakers have looked for alternative ways to fuel our transportation needs. Most popular today are gasoline-electric hybrids, but more recently, fully electric vehicles have been in the spotlight as the most green and efficient option available today.

 One challenge for the EPA was how to relate the fuel efficiency of fully electric vehicles to consumers. We are all used to the standard MPG – or miles per gallon – rating to compare the fuel efficiency of gasoline powered vehicles, so the solution has been to provide a MPGe, or miles ger gallon equivalent, rating for all electric and hybrid vehicles.

The MPGe metric was introduced in November 2010 by the EPA to label the fuel efficiency of the new Nissan Leaf and Chevrolet Volt electric cars. The ratings are based on the EPA’s formula, in which 33.7 kilowatt hours of electricity is equivalent to one gallon of gasoline. This is based on the energy content of gasoline: burning one US gallon of gasoline is 115,000 BTU. The formula for calculating MPGe is shown below.

Two things must be taken into consideration for MPGe of electric vehicles: one  is the energy consumed to generate the electricity necessary charge the battery; and the other is the transmission efficiency of that electricity from its source into the battery. This makes the calculations much more difficult, but it is essential for getting an accurate depiction of the fuel efficiency of electric vehicles.

2012 Ford Focus Electric

 Even with all those factors taken into consideration, new all electric vehicles have impressive fuel efficiency. The 2012 Ford Focus Electric gets 105 MPGe and has a range of 76 miles. Certainly not capable of road trips, but it will get most people to work and back, and perhaps a trip to the grocery store, with some charge to spare. This satisfies what most people do with their cars on a daily basis, and can save a good amount of money in the long run on gas.

Does MPGe make sense to you?

What is a Mass Air Flow Sensor?

A Mass Air Flow Sensor (MAF) is a device that measures the volume and density of the air entering the engine.  It is the first sensor to read the amount of air entering the motor. The MAF is made up of an air temperature sensor, an electronic control unit, and a hot wire.  The main job of this sensor is to convert the amount of air coming into the vehicle into a voltage signal.  Along with the assistance of oxygen sensors, the MAF provides the Engine Control Unit (ECU) with vital information. This data lets the ECU know how much fuel to inject, the timing of ignition, and when to shift a transmission.

There are two main types of mass air flow sensors in automotive engines, the vane meter and the hot wire. The vane meter is an older style.  It measures the amount of air with a spring loaded flap attached to a resistor.  The vane meter is not used as often as the hot wire because it restricts airflow, the moving parts wear easier, and finding a space to mount it is difficult. On the other hand, the hot wire style has minimal airflow resistance, it’s smaller, it has no moving parts that wear, and it responds very quickly to changes in air flow.  So, basically the hot wire is a skinnier, smarter version of the vane meter.

If your Mass Air Flow Sensor is malfunctioning your car may idle erratically, run lean, try to stall, and the throttle could decrease at highway speeds.  If you have a digital scanner you can make sure that your MAF is to blame by hooking the scanner up to the housing circuit and checking for codes. In some cases the sensor is just dirty and needs to be cleaned, but more commonly the part is broken.  MAFs are rarely repairable and a new one will run you a couple hundred dollars.

What is a Crank Position Sensor

Modern engines run by using a number of specialized sensors such as Air Fuel Ratio Sensor or O2 Sensor units. While the air flow in an engine is extremely important there are other factors that need to be measured such as the position of all the parts of the motor at any given time.

The way this info is calculated is through sensors such as the crank angle sensor and the cam angle sensor. These units measure where the rotation angle of the crank and the cam shafts respectively. The cams and the crank must be kept in specific positions to each other since if they are not the valves will be smashed by the pistons.

The ECM controls the engine and if it detects that the cams and the crank are not in the specific location it will retard the timing or kill the engine all together. The ECM will do this to protect the motor from damage, if the timing gets too far off it can potentially damage the engine internally.

Timing also dictates how much horsepower the engine makes and how the fuel is burned. If these sensors fail the combustion of the engine can get all out of whack which is potentially dangerous. Besides the fact that the pistons can impact the valves there is the factor of detonation. This occurs when the fuel mixture is wrong and the explosion in the cylinder is not in the correct location and it takes place faster than it should. There are some instances where the combustion of the fuel takes place to quickly and in a specific location on the cylinder wall which will cause damage to the block itself. This detonation can even cause holes in the block or melting of the pistons. For all modern cars it is a good idea to check all these sensors when the car is in for service. They do play a pretty major factor in the life of a vehicles motor. 

How to Determine Issues with an Oxygen Sensor

Many car issues are easy to determine but others are more elusive. Issues with an O2 sensor or Air Fuel Ratio Sensor can be extremely difficult to determine. Many a time the ECU will determine that the car is having an issue but when it comes to o2 sensors that issue may not be where the ECU says it is. More like the issue is being detected where the O2 sensor is.

When there is an issue internally with an engine the sensors are the first place that will show the signs of the problem. The reason for this is simple, all of the gasses leaving the engine pass these sensors and if there is excess fuel or burnt off oil it will be deposited on the oxygen sensor causing failure.   A failure of the o2 sensor will require replacement of the unit but it will also require the other issues to be fixed before the sensor is installed. If the other issues are not taken care of the o2 sensor is going to fail again and most parts suppliers will not warranty a part with foreign debris build up on the unit. Many times the issue that are causing the failure of the sensor and much larger than the electrical system many involve the fuel system or oil being burned off in the motor. A good example, when a turbo is failing it may send a large amount of oil though the engine and the left over burnt oil has to go somewhere after the ignition in the cylinder. The oil travels through the down pipe where it hits the sensor and not only gives a bad reading but also cakes on destroying the unit as well. These are just a few of the issues that can cause debris build up on the sensor and it is recommended by almost everyone in the car industry to take you to be inspected by a mechanic before buying parts like an O2 sensor.