How to turn AAA batteries into AAs

A truly A+ hack.
Close up to a stack of AA batteries

Don't interrupt movie night when your remote decides to die on you. Hilary Halliwell / Pexels

Of all the annoying things that can happen on a lazy Sunday afternoon watching TV, running out of AA batteries for your remote might easily be in the top 10. Luckily, there’s a hack for that: you can use AAA batteries instead. 

Just wad up some aluminum foil and place it between the battery and the spring so that it fits snugly. It’s a perfect solution if your gamepad dies or you cannot be bothered to go to the store to get some AAs. 

This trick has been around for a while and it’s currently making the rounds on TikTok again. But you can’t trust everything you see on your For You page, and some of those viral lifehacks are duds or even just straight-out dangerous. We wanted to know if this is one of them, so we turned to the experts.

Spoiler alert: It actually works

“This is definitely a valid trick,” says Arthur Shi, who leads the technical writing team at iFixIt, a company that sells repair kits and writes repair guides for just about every gadget you can think of. He even goes further and says AA and AAA batteries are actually not that different.

[Related: An AI called Dragonfly is helping design faster-charging batteries]

Alkaline batteries from AAAA size up to D cells have the same operating voltage, Shi explains. This means non-rechargeable batteries like these all offer 1.5 volts of power, so there’s no electrical reason you can’t use them interchangeably—they just won’t physically fit right into the battery slot in your device. That’s where the tinfoil comes in: it allows the battery to fit snugly in place while still conducting electricity.

“Aluminum foil isn’t the best conductor,” says Shi. “But for low-power devices such as those powered by AA batteries, it works just fine.”

If you don’t mind spending a little money, you can also opt for buying a dedicated product for the job. You can buy battery adapters that turn AAA batteries into AAs, or even D cells. Shi says these are better than aluminum foil as they facilitate more stable physical contact.

Maybe buying one of these adapters means you’ll never have to purchase any battery bigger than AAA for the rest of your life. Technically, you could, but that’s far from a perfect solution.

The downside

It would be too easy for tin foil or a battery adapter to completely solve the AA problem, so of course there’s a downside to it—the lifespan. Devices powered with a smaller battery just don’t run as long as they would when using a right-sized juice source, simply because smaller gizmos store a smaller amount of energy. 

[Related: The best rechargeable batteries for 2023]

But it’s not just a matter of size. Shi says that as a rule of thumb, cheap D-cell batteries, for example, have less power than a good AA, and the heavier the battery is, the more energy it will pack.

So consider tin foil as the perfect way to avoid a trip to the store on a lazy day. But don’t be surprised if a week later you find you’ve drained all the AAAs you had at home. It’ll buy you some time, but it’s not the end-all solution.