Today marks the start of Daylight Saving Time, and it’s time for the Czar to obey his annual tradition: reminding Dr. J. that it’s Daylight Saving Time, not Daylight Savings & Loan time.

With that out of the way, the Czar wanted to remind you—and the media, really—that today is also the start of the semi-annual bad advice: the reminder to change your smoke detector batteries.

Back in the 1970s, when smoke detectors were getting commonplace in homes, some local fire department came up with a great idea that—in the lingo of the 1970s—“went viral.” When you change your clocks, change your smoke detector batteries! After all, if you went more than six months on the same battery, you were risking quite a bit.

Of course, that was based on disco-age battery technology: today’s 9-volt batteries can last a long time, but that isn’t what has the Czar concerned.

In the 1970s, Daylight Saving Time went from April to October—about six months, exactly. Perfect for changing batteries.

However, since 1986, this hasn’t been the case: Daylight Saving Time is now longer; and since 2005, the duration was extended yet again: early March to early November. This means, math heads, that you are changing your smoke detector batteries in four months, but then not again for eight months.

This means—if smoke detector batteries aren’t good after about six months—your smoke detectors are at risk in September and October, and you’re chucking out still useful batteries in March.

The Czar’s advice: change your batteries in July and January, say New Year’s Day and Independence Day, and ignore the drones on the local news channel. The Czar changes all the household batteries on those days: the garage keypad, the emergency weather radio, all alarm clocks, the thermostat, the television remotes…everything. Indeed, we keep a list on hand of all the batteries that need changing and what cell types are required for each device. Saves a lot of time, which is why the Czar is clearly superior to most people you will meet.

But back to smoke detectors: cheap 9-volt batteries—usually identifiable by bright neon colors and helpful manufacturer names like スーパーハローキティバッテリー—have a capacity of 100 milliamp hours. Alkaline and especially Lithium (something ‘Puter should really be on) batteries can last multiple times longer, but let us look at a worst-case scenario.

A modern home photoelectric smoke detector operates in standby mode—sipping a tiny 200 milliwatts at most. This means that a cheap 9-volt battery can last up to five or six years before it went low. Longer, indeed, if you buy nicer batteries like lithium cells.

The Czar will likely continue to change his batteries every July and January, but really, he could change them much less frequently. The point is that if the fire departments across America were serious about 6-month battery changes, they’d disassociate the clock-change = battery-change gimmick.

And no, fire departments across America are not serious about changing your batteries every 6 months: they’re serious about people who forget to change their batteries at all. Based on the Czar’s numbers above, you can see how much effort it really takes to have a dead smoke detector in the home; but being that stupid does take a lot of effort. Alas, millions of Americans are up to the task.