Here’s why you can’t charge a battery in 15 minutes

One of my favorite older articles says, “The problem with everything — yes everything — is the battery.” It was true then, it was true a decade ago, and it’s true now. If battery tech had improved at the same rate and in the same way as computer tech, we’d all have batteries the size of a pinhead that lasted for a month. But we don’t have that, and that’s the problem.

Look at any of the incredibly detailed teardowns over at iFixit and you’ll realize that most mobile devices are about 50% battery. Not only that, you don’t need me to tell you that it takes way too long to charge something. The fastest chargers for electric cars still take about 20 minutes to get you to 90% charge. The fastest cell phone chargers take about the same amount of time (of course there’s less energy involved.) Considering how much we use electricity and batteries, you’d think that there would be a better, faster way.

Charging sucks. 

Literally. It sucks power from the wall and stores it. That’s how your battery becomes useful. That’s all well and good but none of us likes to stand there and wait while our batteries charge, especially if trapped in an airport for unexpected hours. It is during that prison term that we wish for batteries that could charge in seconds, leaving us free to live our lives untethered from the wall.

At Solid Signal, we’re often asked about rapid battery chargers. There are a lot of articles out there about them. What they didn’t explain was why you can’t charge a battery in 15 minutes.

Here’s the problem

As batteries charge, they also heat up. Heat is the sworn enemy of batteries. It causes them to swell and crystallize and in general stop working. Enough heat, and a battery will explode. (Which, by the way, is not a good thing.) It probably is possible to charge a battery in 15 minutes but if you did, the battery would probably would be permanently damaged. That’s why modern cell phones have circuits that prevent you from rapid-charging your battery like that. If you did something like hooked up a 12 volt, 20 amp source to your battery (which you would have to build yourself) it still wouldn’t charge in 15 minutes. It might fry the phone but even that isn’t likely.

What about chargers for electric cars that can deliver all that power so quickly?

As I said, modern electric car chargers are capable of giving you a 90% charge in 20 minutes. At least, some of them can. Typical home chargers still take all night. But if you pull into one of those rapid chargers, you’re getting a massive amount of power very quickly. Why can’t cell phones do that?

Electric cars have sophisticated cooling systems and stiff, rigid battery compartments. These two things, along with the sensors that make them all work, mean that you can shove a lot of power into them without worrying that they’ll turn into bombs. If you put that stuff in a cell phone it would literally be the size of one of those 1980s brick phones. I don’t think anyone wants to go back to that.

What about new tech?

A decade ago I told you about a new technology that could make batteries obsolete. This new technology lets you charge up quickly, because it doesn’t use chemicals like today’s batteries. It’s more resistant to heat and doesn’t break down. The problem is that nothing ever came of it. In the last decade there have been a steady stream of stories about better batteries. The truth is that most of them amount to nothing.

Still, I keep holding out hope. I think we’re at the point where there really needs to be some transformative change in batteries, and I have to say, the sooner the better.

About the Author

Stuart Sweet
Stuart Sweet is the editor-in-chief of The Solid Signal Blog and a "master plumber" at Signal Group, LLC. He is the author of over 10,000 articles and longform tutorials including many posted here. Reach him by clicking on "Contact the Editor" at the bottom of this page.