Electric vehicles, are they ready for prime time?

By Joe Lafiandra

If you own or are thinking of buying an electrically powered vehicle (EV) there is lot you should know about the battery that powers the car. The bad news about EV batteries is they are prone to burst into flames if not treated “gently.” The auto manufacturers know this and are doing their best to prevent this from happening but, the very nature of the materials in the battery makes them a hazard in an automobile. By “gently,” I mean preventing the battery from getting either too hot or cold, making sure it isn’t charged too quickly, too much or too little, and making sure that accidents don’t cause hidden damage that will result in fires long after the accident event.

A recent article in the Wall Street Journal entitled “Electric-Car Battery Fires Complicate Wider Rollout” describes challenges that EV manufacturers have had with Lithium-ion batteries that power the car. As a result of unexplained battery fires, General Motors is recalling 69,000 Bolt cars worldwide. The article states that “Bolt owners shouldn’t park their cars in their garages before bringing their vehicles to dealerships to limit the batteries’ charging capacity to 90 percent until a permanent fix can be found …” Hyundai, Ford and BMW have also issued recalls for new battery powered cars in recent months.

 EV car fires are still very rare, statistics show that car fires are 20 to 50 times more prevalent in gas driven cars. This I explained by the fact that EVs represent approximately 1.5 percent of cars on the road in the U.S. but, it is sure to increase as the numbers of EVs increase. Almost all gas powered car fires are the result of a collision, they don’t just burst into flame sitting in the garage.

Don’t get me wrong, I love EVs. To plug my car in overnight and drive away in the morning without worrying about getting gas is a great idea. Unfortunately like all new ideas, the hard details of owning an EV will eventually intrude into your life. Battery manufacturers are doing their best to make batteries smaller, lighter and have greater mileage between charges. 

They are also trying new combinations of materials to meet these ends. The science of battery design is continuously in a state of improvement. Any mass market product like a car places many constraints such as cost, reparability and safety on car designers. There is a learning curve in manufacturing a new component such as a lithium-ion battery for automobiles. 

Car manufacturers have been building internal combustion powered vehicles for over 100 years and have ironed out most the problems over the years and now produce a reliable and safe car. The same can’t be said for EVs. We are at the beginning of the learning curve and new problems will pop up out of nowhere that have to be solved to make EVs a safe choice for everyday living. Forcing consumers to buy only EVs when California’s law comes into effect, doesn’t help, because many problems with EVs safety still have not yet been solved.

In this article I will only discuss the battery problems with electric cars. There are other problems with a full replacement of the internal combustion engine car with an EV. Considerations such as cost, battery life, driving range, resale value and reparability of an EV will be left for a future article. 

All modern EVs use a Lithium–ion battery. This battery is composed of cells that are made of various metals, plastics, graphite and a very flammable electrolyte. The materials are usually in the form of a long strip that is rolled up into a broom stick width and stuffed into a metal tube, sort of like longer “C” cell that we are all familiar with.  As noted previously, battery chemistry is in a state of flux with different manufacturers trying different combinations of materials to get a maximum energy density in a small size. The energy density of a battery determines the number of miles the car will travel before a recharge is needed.

So how many individual cells make up a battery in an EV? The answer is as many as 7,100 in a Tesla Model S. Its battery pack which weighs 1,200 lbs. is placed under the body of the car and represents approximately 22 percent of the cost of the car. The GM Bolt has a smaller number of batteries, 288 cells. These battery packs have to be cooled by air or liquids to prevent overheating. They also need to be heated in low temperature environments in order to prevent degradation. 

So what is causing battery fires? These fires are caused by what is known as “Thermal runaway.” If one of the 7,100 cells is overloaded either by an internal manufacturing defect, an internal short circuit caused by aging, excessive heat or cold or damaged in a collision, the cell overheats, bursts and catches on fire. The electrolyte is flammable and the fire soon spreads to the adjourning cells, which causes a chain reaction that engulfs the entire car. Temperatures over 1,000 degrees are typically produced in such fires. 

Firefighters are faced with unique problems with EVs. In some cases, putting out an EV fire requires jacking up the side of the car and flooding the underside with water. Contacting a live battery is a hazard. The battery cells are hooked up in such a manner to produce approximately 400 volts of Direct Current for the car’s motors. This is less than the 600 volts of the Metro third rail line but will kill you just as quickly. 

Collisions are especially insidious, there may be no apparent damage to the vehicle but the battery cells may be internally damaged and burst into flames hours or days later.

Operating the battery under temperature extremes, excessive charging or discharging cycles or just plain aging changes the internal battery chemistry which can lead to fires. In some cases, batteries develop what are called “dendrites.” These are miniature deposits of metal in the insides of a battery cell. It’s a microscopic version of stalagmites that develop on the floor of caves. These dendrites silently grow inside the battery until they pierce an insulator and short circuit the battery cell. Then the battery caches fires and undergoes thermal runaway. 

These are some of the problems of EV batteries. Many resources on the web are available that explain the state of the art of EV battery development. I suggest you review them if you are seriously considering owning an EV. There is no doubt in my mind that many of these problems mentioned can and will be solved but, as evidenced by the recent recalls of many different EV models, more extensive research and development is needed before a safe and reliable EV is sold to the general public.

Joe LaFiandra writes a regular column, “It seems to me” for the Blue Ridge Leader.