How to Make Lithium Charger

199,010

194

60

Introduction: How to Make Lithium Charger

You will need this project when you have an extra mobile battery or you need to charge any lithium, Lithium ion or Lithium Polymer battery.

Maximum current is about 650 milliamps. The circuit is designed for batteries of 900mah or higher. Power source can be a 12v Gell cell (Power panel), or can be powered by a car's cigarette lighter.
I use an old 12v DC wall transformer (800ma or more.)

Step 1: The Schematic

The Circuit is simple , you will need the following

LM317 variable regulator
2N2222A or any Transistor handles 800mA
2 Capacitors 0.1 uf
1K POT
1ohm 1Watt resistor ( current limitor )

Adjust R4 to the required output voltage
R1 controls the output current

Step 2: The PCB

Here is the PCB of the project , i have used the "Toner Transfer" method, it's very powerful
and easy .
Using HP Glossy paper and Laser printer gives a good results

Step 3: Final Step

The complete project after soldering the components
i have used a small heat sink for the LM317 in case of charging a bigger batteries.

Be the First to Share

    Recommendations

    • Recycled Speed Challenge

      Recycled Speed Challenge
    • Make it Move Contest 2020

      Make it Move Contest 2020
    • Build a Tool Contest

      Build a Tool Contest

    60 Discussions

    0
    secretsather
    secretsather

    9 years ago on Introduction

    There's nothing wrong with this circuit. It is intended for 2 li ion cells. Just a few notes:
    1. Check the voltages of each cell to make sure they are above 3 volts. Do not use this charger if your cells are below 3 volts.
    2. If you are charging 2 cells, make sure the voltages match, otherwise charge each cell individually.
    3. If you are charging 1 cell, set the voltage (via the potentiometer) to 4.2 (or 4.1 to be super safe) volts before connecting the battery.
    4. Check the resistance of the one ohm resistor to make sure it actually is 1 ohm, or charging current may be increased. 1 ohm will yield approx. 600mA
    5. The battery will never fully charge. As the battery charges, it draws less current. So if your voltage is set correctly, you should have no problems with overcharge.

    0
    guruji1
    guruji1

    Reply 3 years ago

    Hi Secret so one can do a pot instead 1ohm resistance to increase or decrease current? Thanks

    0
    mumbles_mcboomboom
    mumbles_mcboomboom

    Reply 4 years ago

    Hi,

    So I'm building a single-cell charger for a 750mAh battery. What are the equations governing the selection of R1? I'm using a PN2222A transistor. I have the circuit set to output a 4.1 load voltage at the moment. I'm just trying to figure out how to limit the current to 750 mA.

    0
    andreiconstantin
    andreiconstantin

    Reply 6 years ago

    can we make this charge 1or 2 amps remaining adjustable from 4.1 to 7.2?

    0
    Smoog
    Smoog

    4 years ago

    R2 and R3??? What are their value ohms or kilo ohms..

    0
    Yaleh
    Yaleh

    3 years ago

    Hi, would this work or be able to be modified to work with a 48 volt
    battery? I want to make one from 12 Lion 18650 batteries wired in
    series. Thanks.

    0
    guruji1
    guruji1

    3 years ago

    Would it be wise for R1 to be a variable resistor to adjust current? Thanks.

    0
    GeorgeA99
    GeorgeA99

    4 years ago

    quicker cheaper way to make lithium charger--take apart a camera lithium charger or old cell phone and add red and black wired clips.Bingo--charges any single/double series 3.7 batteries. These units are easily found at Goodwill ect or old Canon cameras.

    For those looking to build lead acid charger--here is old timers easy build unit that charges and di-sulfates them.called: Capacitor charger. Check it out on You tube. It just might work out on Lithium if you down scale the input voltage but needs a timer.

    0
    ThijssjihT
    ThijssjihT

    6 years ago on Introduction

    I don't have that 1W resistor. Can I use a bit of constantan wire, or will that create to much inductance?

    0
    ThijssjihT
    ThijssjihT

    Reply 6 years ago on Introduction

    Or can I use 12 parrallel 12 ohm 1/4 watt resistors?

    1
    glitvjaks
    glitvjaks

    Reply 5 years ago

    You can use 12 parallel resistors. Wire is also OK, because inductance is not an issue here (this is a DC circuit), however you will need to use 4 wire method to measure the resistance precisely.

    0
    snowluck2345
    snowluck2345

    8 years ago on Introduction

    Could this me adjusted to handle a 15 amp charge. I put together a small lithium pack that is 3.7v at 15amp hours, I would like to charge it at a resonable rate, I was thinking of just regulating the voltage to 4.1 and letting it go.

    0
    applejuice1998
    applejuice1998

    Reply 8 years ago on Introduction

    You would have to either get a bigger version of the LM317, I know there's one that'll handle 5+ amps. Or check the datasheet for the lm317, there's some circuits in there. ;)
    What do do you need a 15amp lithium pack for anyways? lmao, just wondering.

    0
    Dashing Rainbow Dash
    Dashing Rainbow Dash

    Reply 5 years ago on Introduction

    You could also put several 317s in parallel to bump the current capacity, if you are unable to find a larger regulator.

    0
    Imetomi
    Imetomi

    5 years ago

    Would work with a 7805 regulator? Or without a regulator chip?

    0
    Dashing Rainbow Dash
    Dashing Rainbow Dash

    Reply 5 years ago on Introduction

    I dont think so. A 7805 is a 5v regulator, and a 317 is a variable regulator. The adjustable part comes in when you need to fine tune the set voltage, otherwise, you risk cooking the batteries.