Emergency USB Charger V1.0


Introduction: Emergency USB Charger V1.0

About: I have some interest in electronic. you can find me at https://www.facebook.com/theTechWorks

It is a device that will charge your phone & other other devices that plugs into a USB to charge.

Make it and enjoy.

It can charge your phone up to five time in one full charged battery.

You can charge 4*3 Volt battery with your Nokia mobile charger. It will take time to charge.

Ones it is charged it is ready to charge your phone 5(approx) times. :)

Step 1: Requireed Items

You will require:

  1. LM or MC 7805 +5VDC Voltage Regulator
  2. Heat Sink(Optional)
  3. Type-A Female USB Port
  4. 100uf Electrolytic Capacitor 10-50V
  5. 0.1-0.5uf Capacitor 6-50V (any type would do)
  6. 100-160 ohm Resistor
  7. 12(4*3)V Battery(Series Connection)
  8. 2.2V 20mA LED color of your choice
  9. Bread board
  10. Pref Board
  11. 3 Pin Switch...etc which are present in picture

Step 2: The Circuit Diagram (Simple)

The following picture shows the sketch diagram of Circuit which we want to make.

Step 3: Attaching the Components

First attach all the components on Bread Board and check the output(O/p) is 5V by Multi-Meter or we have 5V O/p Checker. Then Place it on PVC Board and solder it with the help of soldering components Like the picture.

Step 4: Adjustment

Do some holes in the box for switch, Charging Point and USB Hub. Do some adjustment in your box and make it fixed with the help of Hot Glue Gun.

Step 5: Done! ;)

Now that you've finished building your own USB charger, all you have left to do is to put batteries in box and use it.

Remember when you add batteries in series then it will give you sum all voltage and if you connect all batteries in parallel then it will give you sum of all Amp. .

Ones it is charged it is ready to charge your phone.... ;)

Step 6: Demo!

Check It out...... It's Working Properly....

Step 7: Ugrade

In this step you will see a how to upgrade you USB Charger..

Since when you insert your charger and switch is not on then charger LED and capacitors are taking voltage from your battery.

So we put a Zener Diode or an Ideal Diode to save your battery. Here I used Zener Diode of 12 V.

Now question Comes What is an Ideal Diode and Zener Diode??

An Ideal Diode is a diode which allows current to flow in the forward direction but not permits it to flow in the reverse direction.

A Zener diode is a diode which allows current to flow in the forward direction in the same manner as an ideal diode, but also permits it to flow in the reverse direction when the voltage is above a certain value known as the breakdown voltage, "Zener knee voltage", "Zener voltage", "avalanche point", or "peak inverse voltage".

Do connection as like in picture first........



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    31 Discussions

    Please Vote me... With your help it may be possible that i win the contest....PLZ

    Great idea! Thank you for creating and sharing this instructable.

    2 replies

    Wow I love the idea of this, it's so useful in the modern day and age. Seems like my devices are always dying... Awesome job showing each step!

    2 replies

    3 years ago

    The 90% value is = 0.9
    The 80% value is = 0.8
    This value were derive from "how the battery generates its preserve power.The formula can be found on
    Yoobao FAQ site
    (powerbank manufacturer in China).Hope that clarifies your querries.

    15, 8:14 AM.jpg
    2 replies

    Thanks a lot man i will remember the calculation...

    What do you think if i add 3 more batteries of series connection in parallel to other three then the O/p comes 12V and 7000mAp. can we do this to charge any phone more times.

    Glad it helped you understand what i mean...Yes you can do that as long as your DIY board can handle it,as far as i know LM7805 regulators generate heat.(advice add holes on your plastic case for ventilation).You can add 3 batteries in series parallel to that 3 pre installed before.But the downside here,it would be a bit bulky.I suggest you use three 18650 Li-ion batteries with higher mah(ex 3800 mah) wired in series and do it as you planned to double it.

    Anyways,you did upgraded your DIY & that's good.Now it's more appealing than before...Cheers!


    3 years ago

    As a fellow DIY maker i just make inputs here,not to degrade your project or anyone.,I create & build & shared it here,& im open to any comments made on my ibles.,you should be open to any discussion specially if we are discussing your DIY.As im saying i make QUERRIES!Peace!

    2 replies

    your are right as a fellow DIY maker you may just make inputs here, I appreciate that you are giving attentions on my project. I'm ready to answer all of your queries.

    let's remove the topic of how many times it can charge your phone. i took my word because i can't prove you anything with pictures and video. I'm unable to understand charging formula but I think you are telling me from so much confidently that's why i removed the charging limit's from project 3 day's ago. But i want to learn all the details about the formula... the calculation part


    3 years ago

    Pls..,Read my comments carefully before you respond.

    •Why 90%? Assuming the power bank is well maintained in good working condition and can conserve up to 90% power)
    •(Why 80%? An estimate of 20% power is consumed during the charging/ discharging process)

    Because you ask for it!

    15, 5:22 PM.jpg
    1 reply

    As i said i can't understand the calculation part. Please provide me the full calculation portion .90% of V or amp and 80% of V or amp



    3 years ago

    If your still not convince,just ask me,& i will give u the site that gave the formula how powerbank works..,peace!

    1 reply

    my friend please provide me the site where you get the formula because i'm unable to under stand what are the values of 90% and 80%


    3 years ago

    My friend,no offense,thats not my formula,as i said,i got it from a powerbank maker site from China,& indeed work.Second thing,you havent answer my question,HOW DID YOU WIRE YOUR BATTERIES?,,3rd thing is i said 1 time ,because that
    .77 left wasnt good enough to charge your phone in full..4th Never drain a lion battery,believe me,or it wont charge at all.Now tell me,if you wired it in series,to gain 12vdc.,then how come your battery becomes 3.5Ah when it shows that its only 1.5 Ah!
    & DIY PROJECT should be discussed because you shared it here,& i make queries.,Right?

    1 reply

    in answer of your second question, i put batteries in series and it is gives output 13.65V and 3.5Amp

    Now you are agreeing that to never drain a lion battery that's way i said when .77 left it may charge your phone fully.

    As i said in last comment it is showing 3.5 Amp. because it is a chiana battery