Over five years ago, I purchased an Apple Watch Series 4. Since I don’t always have my cell phone with me, I bought the model with cellular phone capability for $530. I’ve only used that Dick Tracy capability a few times, but it has been nice to have. I mostly use the watch to know the time and date (duh), but I do like seeing my next appointment, getting 2-Step Verification text codes on it, checking the weather, and setting an occasional timer. I find its exercise reminders annoying, but I know I should heed its advice when it nags about me sitting for too long. I also like how it taps my wrist to signal me to turn left or right when using Apple Maps to walk or drive to destinations when I’m at a conference in an unfamiliar city.

This week the device would no longer reliably hold its charge. 5½ years of charging cycles had taken their toll on its lithium-ion battery. The Li-ion batteries in my iPhones have typically started to fail after three years. I extended the life of one phone for a few years by slipping it into an Apple Smart Battery Case. I have grown used to replacing my phones every 2-3 years and my iPads every 3-4 years, and perhaps I’ll be on a 5-year cycle on my Apple Watches.

I could have sent the watch in to Apple for a battery swap, but it has no always-on mode like the current Apple Watch Series 9. I first encountered the low-power always-on mode on my iPhone 14 Pro, and I decided it would be nice to no longer have to wriggle my wrist or tap the watch when it failed to detect my interest in reading the display.

So I spent $500 on a new Series 9 unit, with 0% interest 12-month financing via Apple Pay. I again opted for cellular phone capability, but I saved some money by purchasing the smaller model. Both the 41 millimeter and 45 millimeter versions will fit my wrist, and my 44 millimeter Series 4 watch was occasionally a bit bulky for some long sleeves. Since my use of the watch touchscreen is mostly limited to tapping to set a timer, I don’t think I’ll mind the smaller tap targets. My watch was too old and scratched to get much on a trade-in, but Apple will recycle it for free.

Battery life is something we have had to deal with throughout our own lifespans. When I was a youngster, some of our flashlights and my toys had Eveready zinc-carbon dry cells. They had a black cat leaping through a 9, but I never found that zinc-carbon batteries had nine lives, including the “heavy duty” ones.

So once I could afford alkaline dry cells, I opted for those. We usually bought Duracells, which looked good, although I would also buy Energizer alkaline cells from Eveready, even though the bunny in their ads could be annoying.

The pedant in me is a bit annoyed that each of the dry cells shown here is labeled as a battery, when they are really single dry cells. Traditional lead-acid car batteries can legitimately claim that moniker, since they are an actual battery of six wet cells, while the only alkaline batteries we purchase that are truly batteries, and not merely cells, are the 9-volt ones. I used to show my physics students some dissected 9-volt batteries so they could see how they were batteries of six 1.5-volt dry cells in series.

In the old days, high school physics labs were equipped with Variac transformers at the front so that the teacher could adjust the voltage of a direct current output at each lab station. There were once rooms at both College High and Sooner High in Bartlesville so equipped, but none of the three labs I taught in at Bartlesville High School featured those antiquated units.

So back when I taught high school physics, I invested in a bunch of rechargeable D cells with chargers. I used those in introductory electrical circuits labs so that students could learn how to wire up series and parallel sources and discover their effects on current and voltage. Once students had mastered those concepts, they switched over to using variable-voltage direct current power supplies, and I was happy if we could venture far enough into electromagnetic induction for them to learn how transformers work.

Years ago, I tried using rechargeable cells at home, but found them too inconvenient, and their lower voltage sometimes had annoying side effects with flashlights that were dimmer than expected, etc. In recent years, I have bought Amazon Basics AA and AAA dry cells, which worked okay and were cheaper than the name brands. I purchased some plastic ammunition boxes to keep the cells in. That way, if one leaks, the rest might be spared.

The most expensive battery I have purchased was for my EGO electric lawn mower. The 56-volt 5.0 amp-hour Li-ion battery that came with the mower lacked enough capacity to mow the entire yard, so I spent over $700 on a 10 Ah one. That did the trick, and I’ve used the smaller, lighter 5 Ah battery for an EGO electric chainsaw I purchased as well as a string trimmer.

My current gasoline-powered car is a decade old, so in a few years I will probably be purchasing a truly enormous battery in a plug-in gas-electric hybrid automobile. They say that electric vehicle battery packs last five to ten years, so given my life expectancy I might squeeze in a few such purchases before I encounter a more personal lifespan limit.