Introduction: The BlackBOX-Super Fast Phone Charger (68% in 31 Minutes)

About: Hi, I'm Tamas. I like to build all kinds of electronic gadgets, hope you'll like my ideas. I'm not so active on the site these days, so sorry for the late replies. (Oh, and sorry for my broken English in these…

Hi DIYers! Did ever hapenned with you that you hurried somewhere and your phone was discharged? I think your answer is YES. I heard about phones and charges that can be recharged in 30 seconds, this is awesome, but they have a special battery. My goal/target was to develop a device that is compatible with Lithium-Ion batteries, that usually phones have. And I succeeded to make a device that charges the battery of my phone very fast. Charges the battery up to about 55% then charges slowly up to 100%. A regular phone charger charger the phone equable, this means that reaches 55% in about 45 minutes. My charger reaches 55% about 17 minutes. This is a very big difference, but until 100% I need to wait about an hour.

Please read everything before working!

So the result:

  1. REGULAR Charger: 55% in about 45 minutes, 100% in 1.5 hour
  2. BlackBOX Charger: 55% in about 17 minutes, 100% in 1.3 hour

This is a pretty good result. But it's depending on your phone. The device works only with phones that have a replaceble battery. Most of Android phones have.

When use the BlackBOX?

In the case of an emergency, if you need to give some power to your phone fast.

BUT DON'T USE OFTEN this device, bacause I can't build in a charging circuit, so you can damage your battery. I'll explain in the next step that why I can't build in. That's why I charge the battery only for 30 inutes. In my case this is 68%.

Step 1: How It Works?

So the voltage is increased, I mean that I used a voltage booster/doubler circuit for the 5 volt USB output. This way I'll get a 9 volt outlet. The current isn't enough high to damage the battery so when I connect a discharged battery to it (the battery's voltage is 3.2 volts) the voltage increases quickly to 3.5 volts, because the charging voltage is high, but the current is smaller so the battery won't be damaged. This charging method can't be used frequently because may cause problems. Now start bulding!

Step 2: Tools and Materials


  • soldering iron
  • basic crafting tools
  • electrical tape
  • glue
  • rotary tool or drill


  1. of course a phone
  2. you can use a premade voltage booster circuit or you can build an own like me using a 555 timer, in this case you'll need the following parts:
  3. a USB cable
  4. a 2A 5v AC/DC adapter
  5. 2 germanium diodes
  6. 100k resistor
  7. 100 nF capacitor
  8. 1 nF capacitor
  9. some wires
  10. 555 timer IC
  11. 8 pin IC socket
  12. a plastic box
  13. 10uF cpacitor
  14. 1uF capacitor
  15. and a piece of PCB

Step 3: Soldering

Prepare the soldering iron and following th circuit shematics solder the parts together. Try to minimize the size of the circuit board.

Step 4: Wiring Up

Connect the wires to the 3 way terminal block and go test it with an old phone battery!

Step 5: Circuit Test

The results are amazing!

Plug your adapter in then check the output voltage. 9.04 volts for me, perfect. Connect the battery to the outlet and wait 2 minutes. The voltage 3.35 volts to 3.56 volts. So works without problems.

Step 6: The Box

I used two legs from an electronic component, soldered the output wires to it, and glued in the box with a super glue. Put the battery in the box, mark the positive and negative endings with a pen and glue there the wires. This is very easy.

Step 7: Try to Charge It

When I connected the battery to the charger was fully discharged, and after 31 minutes of charging the voltage increased to 3.88 volts. Awesome!

Step 8: Make a Better Appearance!

Fix the parts with ductape the and wrap the box into electrical tape. Looks much more better.

Step 9: The Last Tests...

Remove the battery from your phone, then put it in the BlackBOX, plug the USB in the adapter, and wait 30 minutes, don't charge the battery for than 50 minutes, because we haven't a Li-Ion charger circuit.

Step 10: The End

If your battery has been charged, you're done. Hope you enjoyed this instructable, and don't forget to vote on me. Thanks for watching!

Epilog Contest VII

Participated in the
Epilog Contest VII

Phone Contest

Participated in the
Phone Contest

Survival Contest

Participated in the
Survival Contest