LED TORCH From Discarded Mobile BATTERY




About: Now I am a retired person, who enjoys life and making small things to pass the time keep myself busy.


Here I have used a discarded Li-Ion Battery which is no more working in a mobile handset.
This Battery may not work in a mobile set but it has got a lot of juce left in it to run a small poket size rechargeable TORCH with 5 LED's. It gives a very bright light and does not need a recharge for quite a long time.

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Step 1: STEP-1

List of Parts.

1.- One PVC flat Box of size 2 x 3 x 1/2 Inches.
2.- One Single pole single throw switch.
3.- Five Very bright White LED's of 5mm size.
4.- One Discarded 3.6v Li-Ion Battery. (Lithium Battery)

Step 2: STEP-2


In this step follow the Circuit diagram and assemble the parts.
The 5 LED's are fixed to the PVC Box.
The Switch is fixed to the Cover of the Box.

All the 5 LED's are connected in parellel with a switch to the Battery.
LED's are connected PARALLEL because the output voltage of the
battery is 3.6 volts and the White LED runs on 3.3vots.

The longer leg of the LED is the positive pole and the shorter leg is the Negitive pole.
The positive pole should be connected through the SPST Switch, to the (+) side of the Battery.
The Negitive pole can be directly connected to the (-) side of the Battery.

Put some foam pieces around the Battery to keep it steady inside the box from any movement.
Put on the COVER and all is done....
Happy Lighting.

Step 3: STEP-3


There is nothing special in this step but to see the Photograph and follow the the circuit.

To recharge the battery put it in your Mobile Handset and CHARGE.
Buy a Lithium Battery Charger which charges many types of lithium batteries.

Step 4: STEP-4

View of the Lithium-Ion Battery

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    43 Discussions


    9 years ago on Step 3

    Hi Dipankar. Perfect instructable just what i need for my spare mobile phone battery. :)

    Just a question, how did you connect the wire ends to the battery contacts? were they soldered?

    1 reply

    9 years ago on Step 2

    What is this sing: http://www.kpsec.freeuk.com/symbols/led.gif

    1 reply

    Reply 10 years ago on Introduction

    Here is a little shameless self-promotion, and direct response to your request.

    I was thinking along those same lines, as I was reading this 'ible.
    then I looked in my electronics junk, er, recycle pile, and inspiration hit.

    My solution will indeed recharge, even the larger cellphone batteries.... but it'll probably take a LONG time. My palm treo battery has roughly 9 times the mAh rating, and I don't think my converted "toys" do ANY kind of quick charging. I think they are full-time trickle chargers, with a "full battery shutoff" circuit.


    Reply 10 years ago on Introduction

    How to Charge a Li-Ion Battery Most dedicated Li-Ion-charge integrated circuits (ICs) are designed to charge the battery in this manner. The charging of a Li-Ion battery consists of three phases: pre-charge; fast-charge constant current (CC); and constant voltage (CV) termination. In the pre-charge phase, the battery is charged at a low-rate (typical of 1/10 the fast charge rate) when the battery cell voltage is below 3.0 V. This provides recovery of the passivating layer which might be dissolved after prolonged storage in deep discharge state. It also prevents overheating at 1C charge when partial copper decomposition appears on anode-shorted cells on over-discharge. When the battery cell voltage reaches 3.0 V, the charger enters to the CC phase. Fast-charge current should be limited to 1C rate (0.7°C rate) to prevent overheating and resulting accelerated degradation. However, cells designed for high power capability can allow higher charge rates. Rates should be selected so that the battery temperature does not exceed 50°C at the end of charge. The battery is charged at the fast-charge rate until the battery reaches a voltage regulation limit (typical of 4.2 V/cell, but 4.1 V for coke-based anodes Li-Ion battery). The charger starts to regulate the battery voltage and enters CV phase while the charge current exponentially drops to a defined termination level. However, the output voltage regulation accuracy is critical to maximizing battery capacity and improving its service life. Less battery voltage regulation accuracy means to undercharge the battery, which results in a large decrease in battery capacity. The battery loses about eight percent capacity if it is undercharged by one percent voltage. On the other hand, less battery voltage regulation accuracy also means the battery is overcharged, which reduces the battery service life-cycle. To safely charge the Li-Ion battery, it only allows initiating to charge the battery when the ambient temperature is between 0°C to 45°C. Charging the battery at lower temperatures promotes formation of metallic Lithium, which increases the battery impedance and causes cell degradation. On the other hand, charging the battery at higher temperatures causes accelerated degradation because of promoting Li-electrolyte reaction. This presents a market need for more accurate, efficient and safe battery charge for portable devices. By Jinrong Qian, Senior Member of Technical Staff, Texas Instruments


    10 years ago on Step 2

    i'm a newbie just trying to grasp basic electronic concepts ....

    .... so you say to connect the LEDs in parallel but mention nothing about using resistors, because this article --> http://www.kpsec.freeuk.com/components/led.htm <-- advises against connecting them in paralel, or at least use a resistor for each LED.

    Feedback needed. Thx.

    1 reply

    Reply 10 years ago on Step 2

    Hi zwarriorx, Resistors are only required when the voltage is above the working voltage of the LED's. All the 5 LED's are connected in parellel with a switch to the Battery. LED's are connected PARALLEL because the output voltage of the battery is 3.6 volts and the White LED runs on 3.3volts. So the led's are slightly overrun which will not matter but will give a bright light.


    10 years ago on Introduction

    does anybody kows the importance of IC in mobile phone battery? what is the diffirrence of double IC to single IC? please i need quik reply. thanks.

    1 reply

    Reply 10 years ago on Introduction

    Hi nikki1920, Sorry , could not follow your Question. There are no IC in a mobile phone battery.


    10 years ago on Introduction

    Does anyone know how to charge one of those batteries safely (without using the original cell phone)