The Dirty Little Secret about Electric Vehicles

Electric Vehicles have gotten a lot of media attention overthe 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. Weuse things like O2 sensors and Air Fuel Ratio sensors, along with catalyticconverters, in order to reduce the impact that gasoline engines have on theenvironment. Recently, companies have been exploring ways to abandon gasolineconsumption all together and produce “zero emissions” vehicles in the form ofelectric vehicles, like the Nissan Leaf. Although people have thoughtfullyexplored 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 symbolLi on the periodic table. It does not occur freely in nature; it only appearsin compounds that are usually ionic. Lithium salts are extracted from the waterof mineral springs, brine pools, and brine deposits. The metal is then producedvia electrolysis from a mixture of fused lithium chloride and potassiumchloride.

The brine is usually pumped to large pools to let the sunevaporate the salts to a high enough concentration. Then this potent solutionis pumped onto trucks and driven to processing facilities. Currently, 61% ofthe world’s lithium production occurs in Chile. Worldwide reserves of lithiumare estimated at about 13 million tonnes. Using the battery efficiency figureof 400 g of lithium per kWh, this gives a total maximum lithium batterycapacity of 52 billion kWh which, assuming it’s used exclusively for carbatteries, is enough for 2 billion cars with the same size battery as a NissanLeaf.

Lithium brine pools

 Problem is, only 25% of the world’s lithium goes into themanufacture of batteries (and that includes batteries for laptops and cellphones).  Lithium is used for processingsilica to make glass, as a major component in high temperature grease, in airpurification systems, in nuclear weapons, and even in pharmaceutical drugs totreat bi-polar disorder. The world’s supply of lithium would be exhaustedrelatively quickly if we tried to run most of the world’s vehicles onlithium-ion batteries.

In response to this claim, many bring up the fact thatLithium batteries can be recycled, and thus diminishing the problem ofdepleting this rare metal. The problem with this is that lithium is rathervolatile at room temperature, so the entire battery has to be cooled down to-345°Fbefore it can be dismantled and recycled. Cooling batteries down to suchextreme temperatures uses a tremendous amount of energy, reducing the favorableenvironmental impact lithium ion batteries are supposed to have.

In reality, with a rapidly expanding population and ballooningconsumption of energy worldwide, there is no magic solution to solve ouremissions problems and save the world. Continuing current habits of everyindividual driving and using inefficient means of transportation, along withthe host of other issues with consumer culture, leaves little doubt that ourcurrent style of living is unsustainable. Save for the unlikely invention ofcold 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 pushfor more fuel efficient vehicles. Along with the development of catalyticconverters, air fuel ratio sensors,and O2 sensorsfor standard gasoline engines, automakers have looked for alternative ways to fuel our transportation needs. Most popular today are gasoline-electric hybrids, butmore recently, fully electric vehicles have been in the spotlight as the mostgreen and efficient option available today.

 One challenge for the EPA was how to relate the fuel efficiencyof 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 poweredvehicles, so the solution has been to provide a MPGe, or miles ger gallonequivalent, rating for all electric and hybrid vehicles.

The MPGe metric was introduced in November 2010 by the EPAto label the fuel efficiency of the new Nissan Leaf and Chevrolet Volt electriccars. The ratings are based on the EPA’s formula, in which 33.7 kilowatt hoursof electricity is equivalent to one gallon of gasoline. This is based on theenergy 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 necessarycharge the battery; and the other is the transmission efficiency of that electricity from itssource into the battery. This makes the calculations much more difficult, butit is essential for getting an accurate depiction of the fuel efficiency ofelectric vehicles.

2012 Ford Focus Electric

 Even with all those factors taken into consideration, newall electric vehicles have impressive fuel efficiency. The 2012 Ford FocusElectric gets 105 MPGe and has a range of 76 miles. Certainly not capable ofroad trips, but it will get most people to work and back, and perhaps a trip tothe grocery store, with some charge to spare. This satisfies what most peopledo with their cars on a daily basis, and can save a good amount of money in thelong 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 thevolume and density of the air entering the engine.  It is the first sensor to read the amount ofair entering the motor. The MAF is made up of an air temperature sensor, anelectronic control unit, and a hot wire.  The main job of this sensor is to convert theamount 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 datalets the ECU know how much fuel to inject, the timing of ignition, and when toshift a transmission.

There are two main types of mass air flow sensors in automotiveengines, the vane meter and the hot wire. The vane meter is an olderstyle.  It measures the amount of airwith a spring loaded flap attached to a resistor.  The vane meter is not used as often as thehot wire because it restricts airflow, the moving parts wear easier, andfinding a space to mount it is difficult. On the other hand, the hot wire stylehas 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 mayidle erratically, run lean, try to stall, and the throttle could decrease athighway speeds.  If you have a digitalscanner you can make sure that your MAF is to blame by hooking the scanner upto the housing circuit and checking for codes. In some cases the sensor is justdirty and needs to be cleaned, but more commonly the part is broken.  MAFs are rarely repairable and a new one willrun 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.