4 battery myths (and why they’re not true)

4 4 minutes read

We all depend on batteries. From our phones to our flashlights, all of us need these tiny energy storage devices to get things done every day. Few of us know how they work. And battery technology keeps changing.

It’s not surprising, then, that so many of us believe battery myths. From storing batteries in the freezer to overthinking how much they are or aren’t charged, here are a few untrue things you might believe about batteries along with the truth.

Myth: Put Batteries in the Freezer or Fridge

A relatively common belief is that storing your household batteries in the fridge or freezer can extend their lifespans. The idea here is that chilling or freezing batteries can slow the chemical processes that cause them to lose charge over time, even when not in use. I can’t find any scientific research that backs this claim, though, and every major battery manufacturer advises that batteries be stored at room temperature. Duracell states on their website that storing batteries in the fridge or freeze “will not…increase storage life”.

And it turns out there are actual downsides to putting your batteries in the fridge or freezer, mostly condensation. Energizer explains that putting batteries in the fridge “can in fact harm batteries if condensation results in corroded contacts or label or seal damage due to extreme temperature storage.”

Now, this isn’t to say that temperature doesn’t matter. Storing batteries in a consistently hot place—for example, in your attic or in the basement next to your furnace—will result in reduced lifespans. Your standard battery is designed to be stored in a dry place at room temperature, between 68 and 78 degrees Fahrenheit.

Myth: Don’t Charge Your Phone Overnight

You’ve probably heard that it’s not a good idea to constantly charge your phone to 100 percent, and as such, a bad idea to charge it overnight. And the thing about this myth is that it’s actually true—or, at least, it was. The reason it’s mostly a myth now is because device manufacturers have taken it upon themselves to do the work for you.

Let’s back up. Modern laptop and phone batteries are lithium-ion, and like all rechargeable batteries it can only withstand so many recharging cycles. You can increase the lifespan of your battery by keeping your charge between 40 and 80 percent as much as possible. That’s according to Battery University, a website with all kinds of information about batteries provided by Cadex, a consultancy that helps large companies like Amazon and Motorola get more out of their batteries. It is particularly bad to store a fully charged or fully depleted battery.

a smartphone charging on a pillow — Go to bed: Your phone will be OK. Image: Getty Images Alavinphoto

This is where battery optimization comes in. This is a software feature that charges your phone up to 80 percent and doesn’t fully charge until you’re likely to unplug your phone. Such software typically keeps track of your daily routine and charges so that the battery will typically be around 80 percent right up until you need to use the battery. On the iPhone this feature is called optimized battery charging and on Android devices it’s called adaptive battery. If you have this feature enabled, you can charge your phone overnight without worrying—the software is doing everything it can to keep your battery healthy.

Myth: Closing Apps Saves Battery Life

Many people, when the battery is dying on their phone, will manually “close” as many applications as possible. The idea is that those applications are taking up resources and closing them will allow the battery to last longer. The problem: this isn’t how phone operating systems work. Both Android and iOS suspend applications you’re not currently using, as reported by multiple outlets from Quartz to HowToGeek.

That’s not to say there’s nothing you can do to get a little bit more juice out of a dying battery. On most phones the screen is the thing that uses the most energy, so turning down the brightness can do a lot. You can also leave the screen completely off as much as possible. Finally, both iOS and Android offer a battery saver mode, which can be found in the settings. Enabling this will stop applications from updating in the background, meaning things like emails won’t be downloaded automatically and your battery will last longer.

Myth: You Need to Fully Discharge Batteries Before Charging

Some people think it’s a good idea to fully discharge batteries before charging them fully, an idea that has its roots in history. Nickel-cadmium batteries were common in the 20th century, and at some point during their lifespan, the story of the memory effect became household knowledge. The rough idea was that if you charged such batteries before fully depleting them, they’d have less charge over time. This wasn’t exactly true.

According to an article in the Journal of Applied Electrochemistry, the origins of this idea was extremely specific to the aviation and aerospace industry, where batteries were routinely depleted to exactly 25 percent and then fully charged. The effect occurred after repeating this hundreds of times, which isn’t something that happens in standard household use. And even in the original scenario, engineers were able to negate the effect with a few software tweaks. Put simply: Memory is a real thing but it doesn’t apply to the AA batteries in your remote control.

And, in any case, most modern rechargeable batteries don’t use nickel-cadmium. The memory effect has never been found in lithium-ion batteries, so even if the effect was real in the household context, it doesn’t apply to modern devices.