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Category: Commentary (Page 1 of 27)

Commentary on most any topic.

Lithium Battery Hazard

Lithium batteries are more dangerous and more delicate than I or my friends thought. It’s good to be aware of the dangers and treat them properly to minimize the danger.

For years now we’ve seen occasional reports of electric vehicles, cellphones, and notebook computers catching fire and sometimes burning spectacularly. It’s not common but it happens. One might say, “Oh, but that’s EV’s. That’s a special case.” It’s not. For the first several years, Tesla’s EV batteries were built out of 18650 lithium cells, 4,000 of them. These are the same cells found in power tool battery packs from Black & Decker, Porter Cable, DeWalt, and the rest. These are the same cells found in some notebook computers, flashlights, and many vaping devices.

There are several lithium battery chemistries. What I’m talking about here is the most common: NMC or Nickel Manganese Cobalt Oxide.

One of my 18650 Lithium NMC Cells

18650 refers to the physical size of the cell, 18 mm in diameter by 65 mm long. Other sizes exist but the 18650 is the most common shape.

An Incident Occurs

Like everyone else, I’ve been using lots of these batteries without issues. What caught my attention was an incident that happened a couple of weeks ago to a friend and co-worker. He got up in the morning to make coffee and noticed an odd smell. It smelled like overheated plastic, or failing electronics, or a pot left to burn dry on the stove. He walked back and forth in the house and determined the smell must be coming from his bedroom. Nothing was immediately apparent so he searched and found the cause. Under the bed was a plastic tote where he kept the batteries for his cordless garden tools. Since it’s been winter, those batteries had been there untouched for almost six months. Now, one of them was warm and plastic housing showed evidence of melted plastic and a hole where the plastic had boiled. He took the tote outdoors and called me. I went and took a look, took some photos, and noted the strong smell. Despite opening windows and ventilating the house, the smell lingered in the house for several days.

Later, he mentioned that the way the battery attaches to the tool is awkward and that he had dropped that battery on concrete from a height of about 1 meter. This cracked the plastic case. He thought nothing of it, glued the case together, and the battery continued to work normally. This news sent me digging on the Internet for information. I found quite a lot and learned some important things I didn’t know.

Dry Cells (Alkalines) Compared to Lithiums

Cylindrical lithium batteries like the 18650 are much more delicate than dry cell batteries. Dry cell batteries like alkalines are filled with a few simple bulky materials. Close manufacturing tolerances are not required and they are physically robust. Dry cell batteries can be dropped, dented, and partially crushed and won’t short-circuit. They usually continue to work. Even if a short somehow occurs, they fail gracefully. The maximum power they can deliver is limited and will not result in pyrotechnic jets of white hot flame or violent explosion.

Below is a table comparing old style dry cells introduced in 1898 , alkaline dry cells, and modern NMC lithiums. It shows the total energy content in MJ/kg (megajoules per kilogram), the total energy you can expect to get out of a cell in Wh/kg (watt-hours per kilogram), and the “specific power” the cell can deliver in W/kg (watts per kilogram). More on specific power below.

LeClanche Dry Cell (1898)0.133610-27
Alkaline Dry Cell (1949)0.13-0.6885-19050
18650 NMC (2008)0.742053000-5100

From the above you can see that the differences aren’t that big except in one important way: watts per kilogram or specific power. Engineers use many terms like “specific power” that have agreed-upon meanings. In this case, specific power is the maximum amount of power a battery can produce for a short period of time. Short time meaning seconds or tens of seconds. Related terms would be instantaneous or pulse power (a fraction of a second) and continuous power (a long period of time or indefinitely).

As you can see, a lithium cell can deliver a hundred times as much specific power as an alkaline battery of the same weight. This jaw-dropping power to weight ratio is extreme, on the order of the engine in a top fuel dragster. Or, the engine in a Toyota Corolla producing 3,000 horsepower for a few seconds. It’s extreme. Over a period of a few seconds an 18650 can deliver enough power to heat itself smoking hot if it didn’t destroy itself in the process, which it would. This is the technology that enables the stunning performance of modern EVs.

At this point it should be obvious that short-circuiting an 18650 is a really bad idea. Just don’t. But what if an 18650 could somehow short-circuit itself? That would be really bad and is what we’ll talk about next.

Here’s the Problem

The construction of a lithium 18650 consists of paper-thin strips of film and foil rolled up like a jelly roll with a hundred paper-thin layers. Electronic engineers will recognize this type of construction from the way tubular paper, mylar, and electrolytic capacitors are made. This means that the positive and negative electrodes are very close together throughout the entire cell making it sensitive to dents, compression, bending, twisting, or any deformation from any direction. An unfortunate impact or dent can cause the cell to short-circuit, now or far in the future.

Diagram of a lithium cell. Note that in a real cell the anode and cathode are thin foil and the separator is also paper-thin.

Making things worse is the formation of so-called “dendrites” in lithium batteries. For years, dendrites have been a mysterious problem that’s plagued lithium batteries. It refers to an effect where repeated charge/discharge of a lithium battery causes the growth of microscopic hairs or threads of lithium. These can short or partially short a cell, resulting in reduced battery life and sometimes catastrophic failure. Recent research has answered most of the questions about dendrites. An understanding of them will hopefully lead to better designs.

This recent research discovered that microscopic fissures in the insulating layer of the cell result in pathways for dendrite formation. Cracks, fissures, or perforations as tiny as 20 nanometers are a problem. (For reference, human hair ranges from 50,000 to 120,000 nanometers in diameter. So we’re talking flaws that are 3,000 to 6,000 times smaller than the diameter of a human hair.) Impacts, dents, or other deformations can result in such fissures which encourage the growth of dendrites.

In other words, if you drop or strike a lithium battery you may have started the clock on a ticking time-bomb. That’s what happened to my friend. He dropped the battery, damaging one or more of the cells, and a year later, after six months of storage, unused, under his bed, the battery short-circuited. Research into impact damage of 18650 cells shows that dents of 3mm and even smaller are a problem. Impacts, especially end-on impacts might show no visible damage, yet the damage is done internally and a time-bomb might start ticking.

Nearly all studies done over the past ten years examined the immediate effects of damage with the main focus on EVs. What happens in an automobile accident? Only recently have studies been done on the delayed effects of impacts and indentations.

One additional fact I discovered is that dendrite growth accelerates rapidly at temperatures above 65C or 149F. This temperature is easily reached and exceeded on the dashboard of a car in the summer sun. Keep your lithium batteries cool and out of direct sunlight.


I hope this information is useful. After learning these things I purchased a steel .50 caliber ammunition box where I now store my lithium battery packs. My box is made of thick steel and I hope this is enough to contain a catastrophic battery failure. It’s certainly better than the canvas kit bag I used to keep my batteries in.

These insights are disturbing. More and more flashlights have lithium batteries. I have three flashlights specifically designed to use an 18650 cell. Many vaping gadgets are powered by 18650s. Any handheld device might be dropped on a hard surface without the user thinking twice about it. And if they are aware of the problem, what then? Discard the battery and replace it or try your luck?



Masks After May 11th, 2023?

At the beginning of the Covid pandemic I remember the utterly surreal experience of walking into a bank wearing a mask. It was surreal because no one reacted, I was not immediately confronted by an armed guard, and no one called the police.

Why did it feel surreal to me? Some states and cities in the United States have had laws prohibiting the wearing of face coverings in public. It’s illegal. Some of these laws have been on the books for 150 years. In the U.S.A. I’ve always just assumed that face coverings, masks, burqhas, etc. are illegal unless I learn otherwise. Wearing a mask in a bank is just asking for trouble.

In New York, it’s been illegal since 1845 for a gathering of two or more people in public to wear face coverings. What about the Ku Klux Klan? The KKK arranges for a court to temporarily lift the ban for their demonstrations and then re-instate the ban. Halloween masks are, apparently, ignored. Face coverings have been illegal since 1949 in Alabama. California had stringent anti-mask laws going way back. These laws were struck down by the court after the State of California was sued by Iranian-Americans in 1979. DC prohibits masks in public after 10 PM. There are many other examples.

What’s going to happen when the Covid-19 Emergency Declaration ends on May 11th? We’re still losing 500 people a day to Covid.

Major Price Increase for Natural Gas

Most everyone who uses natural gas in the U.S.A. is probably noticing or about to notice a shocking increase in cost. The story is that reserves are low and gas producers haven’t been able to drill because of Wall Street profit-taking, so supplies are short.

Well, I don’t believe it and here’s a why. For the past 20 years, winter temperatures in the Northeastern U.S. have been steadily rising due to climate change. I’ve seen the data and recorded some of my own. I’m an engineer and it’s been my habit for decades to keep daily records on gas and electricity consumption.

Where we used to have 12 to 18 inches of snow on the ground at times during winters here in West Virginia, now there’s just a light dusting or none at all. The trend became very obvious about six years ago with almost no snow on the ground for the past six years. The near constant grinding of snowplows is replaced with silence. In 2018 I bought a nice new snowthrower. It’s never been used even once. It’s been sitting in the basement for the past four years.

For the past several years, natural gas consumption in my home has been half what it’s been in the past. From the middle of January to the middle of February, our daily gas consumption for heating was usually 1,000 to 1,400 cubic feet per day. Today it’s 600 or less.

There shouldn’t be a shortage when consumption is half what it used to be. I think the natural gas providers are not happy with their reduced sales due to climate change and have raised prices to maintain profits.

Canned Food is Fine

When I was a kid in the 1950s and 60s, my mother had the opinion that canned food was of low-quality and best avoided. I was young and took her word for it. I maintained this opinion myself into adulthood and sometimes shared it with others. But occasionally I wondered because my own observations and experience didn’t agree. In the late 1990s I became sufficiently curious and learned about it. But first some history.

A Real Short History of Modern Canning

The Dutch Navy were the first to seal foods like salmon in metal cans in 1772. For some reason, this process remained unknown outside of the Netherlands.

The rest of the story begins with French military logistics. In 1795, Napoleon offered a large reward to anyone who could develop a way to preserve foods so that armies could have better provisions when deployed, especially in summer temperatures. As you may know, logistics is what wins wars and availability of food was a major limiting factor in what armies could do.

Fifteen years later, Nicolas Appert won Napoleon’s prize after observing that food cooked inside a sealed jar did not spoil. The reason for this was unknown for another 50 years until Pasteur identified the role of microbes in the spoilage of food. The army worked on developing this process but advancement was slow and the wars were over before useful quantities could be produced.

Development of the canning process continued in Europe and the U.S.A. A process was developed for canning foods in hand-made wrought-iron cans, which worked. But the process was labor intensive and expensive. In 1824, Parry took canned beef along on his voyage to the Arctic. In 1829, James Ross took canned food to the Arctic as did John Franklin in 1845. Some of these provisions were found in 1857. One can was opened in 1939 and found to be edible and nutritious but was not tested for lead contamination from the lead solder used to make those cans.

By the mid-1800s, the wealthy began to see canned foods as a status symbol and novelty. By the 1860s, rising urban populations increased demand for canned food. Many inventions and machines were developed to fabricate cans rapidly. Improved processing methods reduced cooking time from six hours to 30 minutes.

Skipping ahead, a big step was the invention of the double-seam can in 1888. These provided a reliable perfect seal and were called Sanitary Cans. This is the type of can we use today. By World War 1, mass production of canned goods was perfected and large quantities of food, coffee, cigarettes, medications, and ammunition were packaged for the soldiers in cans by the British, French, and the U.S.A. At the end of the war, the companies equipped to make such foods like Nestle and Underwood turned to selling to the general public. Canned foods proliferated. It was now possible for European made foods to be sold in the U.S. and vice versa. Canned tomatoes and canned peaches were available year-round, regardless of the season. It was a whole new world.

Expiration Dates and Safety

I’m old so while I now expect expiration dates on foods, it still seems like a new thing for me. I remember when milk started to bear a date, then eggs, then meat. Before that you could write your own date with a grease pencil if you wanted to. And these were manufacturing or packaging dates, not expiration, best by, or use by dates. Food manufacturers soon realized that by putting “use by” dates on everything they could force supermarkets and consumers to donate or discard food that was past the date and sell a lot more product. Very quickly, manufacturers were all-in on putting dates. Customers began to expect dates.

Today, everything has a date. Even bottled water has a date and many consumers think dates are required by law. They are not. The only things in the U.S.A. required to have a date are pharmaceuticals and baby formula.

When use-by dates began to appear on cans, I just laughed. Cans are hermetically sealed and then heated to sterilization temperature or higher, as high as 130C. Most items are cooked in the sealed can itself. There’s no chance for microbial contamination unless the can leaks.

Modern double seam cans like we’ve used for the past 100 years almost never leak. When they do it’s usually visible. If a can isn’t damaged or bulging and passes the appearance and smell tests, it’s safe to eat.

In the 1970s, a trove of cans of freeze-dried food from 1865 was discovered and tested1. There was no trace of microbial contamination and the food was safe to eat. In the 2000s a trove of cans of various foods from the Depression Era (1930s) was discovered which were sent to a food lab for analysis. All of it was safe to eat. The worst case of degradation was the canned corn, which had lost 30 percent of its nutrient value, but was safe to eat.

Do canned foods last 20 years? USDA says “Most shelf-stable foods are safe indefinitely.”

Back to My Mother

In short, my mom’s opinion about canned food was false. But why did she have this opinion? Thinking back on the stories she told me as I was growing up provided the answer. My mom grew up in a big city in Northern Germany in the 1910s and 20s. By the 1920s, a lot of the food on the table was canned because that’s all that was available. Her mother was an early health-food proponent and went to great lengths to seek out fresh fruits and vegetables, gather wild berries and mushrooms. This made an impression on my mother.

When my mom came to the United States in the 1930s, she was astonished at the abundant fresh foods available in markets everywhere, even in big cities. And like most immigrants, she had the idea that everything was better in the U.S.A., which led to her deprecation of canned foods as inferior.


The truth is it’s not a matter of inferior or superior, it’s a matter of cooked versus fresh. If you want raw or lightly steamed broccoli, that’s not going to happen with a can. On the other hand, the can of broccoli will be there waiting for you years into the future without power-consuming refrigeration or freezers. Canned foods tend to be cheaper not because they’re lower quality but because it’s usually prepared near the farm, doesn’t need refrigerated transport, and doesn’t have to be rushed to the market before it spoils. There’s also less waste that has to be refrigerated and rushed to the market. How much of a broccoli head’s mass amd volume do you actually use? A third? The rest goes in the trash but you paid for all of it to come to you fresh.

If you consider the can itself, it’s made of steel, which is cheap, abundant, and non-polluting in a landfill. Unlike plastics, steel is easily recycled but hardly anyone does because steel is so cheap. If you look at the big picture, canned foods make a lot of sense.

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