Tag Archives: science fair

Alkaline batteries have second lives

Most people assume that alkaline batteries are one-time only, throwaway items. Some have used rechargeable cells, but these are Ni-metal hydride, or Ni-Cads, expensive variants that have lower power densities than normal alkaline batteries, and almost impossible to find in stores. It would be nice to be able to recharge ordinary alkaline batteries, e.g. when a smoke alarm goes off in the middle of the night and you find you’re out, but people assume this is impossible. People assume incorrectly.

Modern alkaline batteries are highly efficient: more efficient than even a few years ago, and that always suggests reversibility. Unlike the acid batteries you learned about in highschool chemistry class (basic chemistry due to Volta) the chemistry of modern alkaline batteries is based on Edison’s alkaline car batteries. They have been tweaked to an extent that even the non-rechargeable versions can be recharged. I’ve found I can reliably recharge an ordinary alkaline cell, 9V, at least once using the crude means of a standard 12 V car battery charger by watching the amperage closely. It only took 10 minutes. I suspect I can get nine lives out of these batteries, but have not tried.

To do this experiment, I took a 9 V alkaline that had recently died, and finding I had no replacement, I attached it to a 6 Amp, 12 V, car battery charger that I had on hand. I would have preferred to use a 2 A charger and ideally a charger designed to output 9-10 V, but a 12 V charger is what I had available, and it worked. I only let it charge for 10 minutes because, at that amperage, I calculated that I’d recharged to the full 1 Amp-hr capacity. Since the new alkaline batteries only claimed 1 amp hr, I figured that more charge would likely do bad things, even perhaps cause the thing to blow up.  After 5 minutes, I found that the voltage had returned to normal and the battery worked fine with no bad effects, but went for the full 10 minutes. Perhaps stopping at 5 would have been safer.

I changed for 10 minutes (1/6 hour) because the battery claimed a capacity of 1 Amp-hour when new. My thought was 1 amp-hour = 1 Amp for 1 hour, = 6 Amps for 1/6 hour = ten minutes. That’s engineering math for you, the reason engineers earn so much. I figured that watching the recharge for ten minutes was less work and quicker than running to the store (20 minutes). I used this battery in my firm alarm, and have tested it twice since then to see that it works. After a few days in my fire alarm, I took it out and checked that the voltage was still 9 V, just like when the battery was new. Confirming experiments like this are a good idea. Another confirmation occurred when I overcooked some eggs and the alarm went off from the smoke.

If you want to experiment, you can try a 9V as I did, or try putting a 1.5 volt AA or AAA battery in a charger designed for rechargeables. Another thought is to see what happens when you overcharge. Keep safe: do this in a wood box outside at a distance, but I’d like to know how close I got to having an exploding energizer. Also, it would be worthwhile to try several charge/ discharge cycles to see how the energy content degrades. I expect you can get ~9 recharges with a “non-rechargeable” alkaline battery because the label says: “9 lives,” but even getting a second life from each battery is a significant savings. Try using a charger that’s made for rechargeables. One last experiment: If you’ve got a cell phone charger that works on a car battery, and you get the polarity right, you’ll find you can use a 9V alkaline to recharge your iPhone or Android. How do I know? I judged a science fair not long ago, and a 4th grader did this for her science fair project.

Robert Buxbaum, April 19, 2018. For more, semi-dangerous electrochemistry and biology experiments.

Penicillin, cheese allergy, and stomach cancer

penecillin molecule

The penicillin molecule is a product of the penicillin mold

Many people believe they are allergic to penicillin — it’s the most common perceived drug allergy — but several studies have shown that most folks who think they are allergic are not. Perhaps they once were, but when people who thought they were allergic were tested, virtually none showed allergic reaction. In a test of 146 presumably allergic patients at McMaster University, only two had their penicillin allergy confirmed; 98.6% of the patients tested negative. A similar study at the Mayo Clinic tested 384 pre-surgical patients with a history of penicillin allergy; 94% tested negative, and were given clearance to receive penicillin antibiotics before, during, and after surgery. Read a summary here.


Orange showing three different strains of the penicillin mold; some of these are toxic.

This is very good news. Penicillin is a low-cost, low side-effect antibiotic, effective against many diseases including salmonella, botulism, gonorrhea, and scarlet fever. The penicillin molecule is a common product of nature, produced by a variety of molds, e.g. on the orange at right, and used in cheese making, below. It is thus something most people have been exposed to, whether they realize it or not.

Penicillin allergy is still a deadly danger for the few who really are allergic, and it’s worthwhile to find out if that means you. The good news: that penicillin is found in common cheeses suggests, to me, a simple test for penicillin allergy. Anyone who suspects penicillin allergy and does not have a general dairy allergy can try eating brie, blue, camembert, or Stilton cheese: any of cheeses made with the penicillin mold. If you don’t break out in a rash or suffer stomach cramps, you’re very likely not allergic to penicillin.

There is some difference between cheeses. Some, like brie and camembert, have a white fuzzy mold coat; this is Penicillium camemberti. it exudes penicillin — not in enough to cure gonorrhea, but enough to give taste and avoid spoilage — and to test for allergy. Danish blue and Roquefort, shown below, have a different look and more flavor. They’re made with blue-green, Penicillium roqueforti. Along with penicillin, this mold produces a small amount of neurotoxin, roquefortine C. It’s not enough to harm most people, but it could cause some who are not allergic to penicillin to be allergic to blue cheese. Don’t eat a moldy orange, by the way; some forms of the mold produce a lot of neurotoxin.

For people who are not allergic, a thought I had is that one could, perhaps treat heartburn or ulcers with cheese; perhaps even cancer? H-Pylori, the bacteria associated with heartburn, is effectively treated by amoxicillin, a penicillin variant. If a penicillin variant kills the bacteria, as seems plausible that penicillin cheese might too. Then too, amoxicillin, is found to reduce the risk of gastric cancer. If so, penicillin or penicillin cheese might prove to be a cancer protective. To my knowledge, this has never been studied, but it seems worth considering. The other, standard treatment for heartburn, pantoprazole / Protonix, is known to cause osteoporosis, and increase the risk of cancer.

A culture of Penicillium roqueforti. Most people are not allergic to it.

The blue in blue cheese is Penicillium roqueforti. Most people are not allergic.

Penicillin was discovered by Alexander Fleming, who noticed that a single spore of the mold killed the bacteria near it on a Petrie dish. He tried to produce significant quantities of the drug from the mold with limited success, but was able to halt disease in patients, and was able to interest others who had more skill in large-scale fungus growing. Kids looking for a good science fair project, might consider penicillin growing, penicillin allergy, treatment of stomach ailments using cheese, or anything else related to the drug. Three Swedish journals declared that penicillin was the most important discovery of the last 1000 years. It would be cool if the dilute form, the one available in your supermarket, could be shown to treat heartburn and/or cancer. Another drug you could study is Lysozyme, a chemical found in tears, in saliva, and in human milk, but not in cow milk. Alexander Fleming found that tears killed bacteria, as did penicillin. Lysozyme, the active ingredient of tears, is currently used to treat animals, but not humans.

Robert Buxbaum, November 9, 2017. Since starting work on this essay I’ve been eating blue cheese. It tastes good and seems to cure heartburn. As a personal note: my first science fair project (4th grade) involved growing molds on moistened bread. For an incubator, I used the underside of our home radiator. The location kept my mom from finding the experiment and throwing it out.