My portable charger is probably the most useful piece of technology I carry with me, other than my phone. I am terrible about remembering to charge my phone until I’m stuck on a delayed subway at 7PM on my commute home, desperately trying to squeeze out the last few seconds of battery life.
So, I’m generally of the opinion that there’s no such thing as having too many backup chargers. (I tend to carry three with me, which I will acknowledge may possibly be overkill.) But buying a battery pack from Amazon or Best Buy is easy.
I wanted to try to make my own — and I managed it without even electrocuting myself once. The DIY battery pack here is essentially a USB phone charger that runs off 9V batteries, all dressed up in a fancy aluminum case (i.e., a mint tin).
Now, it's worth noting that you're not going to get a whole lot of power out of this for charging a phone — most 9V batteries have around 550mAh of charge, or barely enough to charge up half of a modern smartphone. The whole thing is also still far flimsier (and prone to error if you mess up the wiring) than a regular power pack, which, in addition to being safer and more reliable, is also rechargeable.
But still, if you're stuck in a 7-Eleven during the apocalypse, or if you have a stash of 9V batteries that you're looking to use, the homemade charger could work as an emergency alternative.
- A USB car charger, which will serve as the core of your DIY battery pack. Pretty much any model will work for this project — mine came from a gas station for a couple of bucks.
- A 9-volt battery clip, which looks like one of those black pads with the two snaps to connect a battery with wires coming out. You can either purchase one (they’re pretty cheap) or salvage one from somewhere. It’s what you use to hook up the 9V battery that actually powers the charger.
- Obviously, you’ll also want a 9V battery or two, too.
- A soldering iron, which you’ll need that to attach the wires to the charger. If you’re not someone who can safely use a soldering iron, this is a good time to find an adult or a friend who can.
- An Altoids mint tin — eat the mints first — and you’ve got a convenient place to store everything
- You’ll also need some tools (pliers, hammer, a nail) to punch a hole in the side of the tin, and some electrical tape to hold everything down.
Putting it together
Once you’ve gotten everything you need, putting the charger together is pretty simple. You’ll first want to take apart the plastic housing of your car charger using a pair of pliers, and extract the internal hardware. You’re looking for the USB port that’s attached to a circuit board.
Next, heat up your soldering iron, and carefully and securely solder the lead wires to the charger. The red wire (positive) goes to the spring (which, unlike my version, you’ll probably want to trim down a bit) and the black wire (negative) goes to either of the two side panels. It’s very important that you don’t mix those up.
After you’ve gotten everything soldered together, you’ve technically got a working DIY charger. But, you probably don’t want to be carrying around exposed power wiring like that in your pocket, so you’ll want a case.
Taking a hammer and a nail, carefully punch some holes in the side of your mint tin, widening with a pair of needle-nose pliers until you’ve got a space for the USB port to poke through. Then, tape everything down with electrical tape, plug in a battery and a cable, and you’re good to go!
(Or maybe when you’re at the gas station to buy a USB car charger, just buy a rechargeable one instead. It’s probably easier.)