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




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!

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    Gomi no Sensei
    Gomi no Sensei

    7 years ago

    This is without a doubt one of the most DANGEROUS instructables I've ever seen !

    My workmate tried the same circuit and forgot to unplug it because of a phone call. It exploded and made a 2ft fireball at his desk, if he'd been sitting there he could've been killed.

    Any unregulated lithium ion battery charger that has no timer or turn off feature is DANGEROUS..
    Search YouTube for "lithium ion battery exploding"


    7 years ago on Introduction

    This thing just can't work, and here is why.

    The 555 can only provide 200mA at the output, so as soon as you plug the battery the load becomes too high and effectively the whole circuit stops working as a doubler and all you get is the voltage drop of two diodes (BTW, you said to use germanium diodes, but you clearly used 1N4007 silicon diodes) from Vcc to the battery. It is really an inefficient and dangerous way of charging a lithium battery (if you want to make a wuick charger get a couple of TP4056 modules and wire them up in parallel, it's not the best way but it will work way better than your circuit).

    Using a boost converter only makes sense if the battery voltage is higher than the supply, but it's not the case with lithium batteries and 5V supply.

    Fast charging technology uses a 9V supply that can provide up to 18W at 2A (which is better than 3.6A at 5V because too much current in the wires and in the connector would cause troubles) but then the phone has an integrated buck converter to bring the voltage back to the minimum voltage needed to charge the battery, at a higher current (up to 4A).


    7 years ago

    Charge speed highly depends on current... A 9v voltage is dangerous and will not help charging faster. Beside... Lithium based batteries have a particularity : the battery voltage is not directly proportionnal to the percentage of capacity. It can vary by 30% with the cell state of health, temperature, and the way they are charged ('memory') ... I doubt that the battery is really charged. Did the voltage fall quickly ?


    7 years ago

    There charged slowly due to damage to the plates caused by fast charging. Also I'm pretty sure you would be over heating the battery doing this.

    Highly recommended NOT to try this. Dangerous to the point of battery bursting into flames.

    Deadly shadow
    Deadly shadow

    Reply 7 years ago

    I completely agree...this is not true way for fast battery use 5V 2A maximum for charging - do not charge yours phone with 9V...Battery can explode from heat..


    Reply 7 years ago

    Please try it with the same circuit with an old battery in a safe area, and you'll see that the battery doesn't heats up.


    Reply 7 years ago

    I tried it out a few times and the battery won't be damaged because the current of this 555 timer voltage doubler is small, and increases only when the 9 volts drop to 3.5 volts. But, first time try it with an old battery. Don't use often for more and don't leave in for more than 30 minutes. If you follow these rules can't happen nothing bad.