Thursday, May 17, 2012

Make this Li-Ion Battery Charger Circuit


It is generally advised that a Li-ion battery should be charged with utmost care and caution as these type of batteries are prone to instant damages or explosions if the specified charging measures are not employed. Here we discus a Li-ion charger circuit which has been specifically designed for charging all types Li-Ion Batteries very safely and without any considerations.



Thanks to TEXAS INSTRUMENTS for providing us with this wonderful chip, the LM3622 which is an excellent Li-Ion charger, controller device. The IC has been designed for generating a constant current at constant voltage, a basic prerequisite for all Li-Ion batteries. The IC may be configured for charging a single Li-Ion cell or a pack of many.
The circuit using the IC LM3622 can be fed with voltages right from 5 to 24V depending upon the charging needs and the connected battery. The IC does not require any precision external resistors for implementing the functions. Moreover, the IC has a negligible drain of less than 200nA of current from the battery in the absence of an input voltage.
The in built circuitry of the chip accurately regulates the charging current through the principle of temperature compensated band-gap reference. The current is regulated, however its done via an external current sensing resistor.
The band gap principle results in an efficient operating control performance of the circuit and also of the input supply voltage.
The circuit diagram illustrates a low drop out linear Li-Ion battery charger design which is capable of charging a single 3.7V Li-Ion Cell.
For enabling low voltage detection, the switches J1 and J2 may be appropriately selected.
The IC starts the charging process by first detecting the voltage of the cell and “enable status” of the low voltage detection.
The transistor Q2 immediately comes into the operating condition as soon as the connected battery hits target regulation level, determined by the internal setting of the IC.
Q2 now begins supplying a regulated voltage to the connected battery, initiating a constant voltage charging mode of the circuit.
In the above situation the battery receives a constant regulated voltage across its terminals, while the charging current is monitored depending upon the level of charge over the battery.
On reaching a full charge condition, the charge current to the battery is significantly reduced to a safe value.
For more information, you may refer to the following article.


34 comments:

  1. This article is very in making a portable battery charger for mobiles but as the source of charging i want to use another li-lion batteries(like the that are in laptop battery) so how can i use that as that are also of 3.7v and can u please tell their Ah ratings as i couldn't find it on the batteries

    ReplyDelete
    Replies
    1. Laptop batteries may differ with their ratings depending upon the specs.

      However the ratings are very high than a cell phone battery, so can be ideally used for charging a cell phone via the circuit shown here:

      http://homemadecircuitsandschematics.blogspot.in/2012/03/how-to-make-simple-dc-to-dc-cell-phone.html

      Delete
    2. Plzz can you help me, I need to do this circuit!! I want to order the IC and the transistors q1 and q2, what is the exact code of this IC?
      Thank you:)
      and if I couldnt find this specific IC is there any other alternative?

      Delete
    3. LM3622 is the exact code of the IC.

      There's no other alternative, you may try this circuit though:

      http://homemadecircuitsandschematics.blogspot.in/2013/01/how-to-charge-25-nos-li-ion-cells-from.html

      Delete
    4. Ok thanks :)so the LM3622-4.21 is good for this circuit?
      one question more plz, did you simulate this circuit using PSpice?
      I mean, are you sure it charges a li-ion battery? I tried designing the circuit on PSpice but couldn't find the transistors and the IC code to use them! how can I add them to my libraries? should I use the newest version of PSPice and what is it?
      Thank you :)

      Delete
    5. Just want to make sure :p
      This circuit charges a phone battery li-ion cell right??

      if I want to have the circuit as hardware what battery would i ask for from market ?

      Thank you again :)

      Delete
    6. Sorry again, but my last question :p

      I want to design this circuit on PSPice and then I will do it on PCB to use it later in a device, I need the input from mechanical motion source, what do you suggest ??
      Your help much appreciated :))

      Delete
    7. You can be absolutely sure about the circuits functioning because it's been taken from the datasheet of the manufacturer (Texas Instruments)

      the name is more than a guarantee. for further details, you may check it here:

      http://www.ti.com/lit/ds/symlink/lm3622.pdf

      Delete
    8. Ok, but what about Pspice ? how can I model this circuit on Pspice, I still cant find the LM3622 and the DTA143ZKA :S can i replace them by other components for the simulation ? Am asked to do simulation cant only rely on hardware

      Delete
    9. I normally do not rely on simulators, and never use them so can't say much about them.

      You cannot replace the above IC with anything else :-(

      Delete
  2. i have removed the li-ion cells from the battery and their individual ratings are 3.7v and 2200mAh so i want to use them for charging the mobile batteries

    ReplyDelete
    Replies
    1. If it's fully charged then you may directly connect its poles with the cell phone battery poles, since the voltage ratings are the same the cell phone battery will get charged safely.

      However it would be better if you charge the cell phone battery inside the cell phone and not directly...

      Delete
  3. to charge the batteries in the cell can i directly connect the charging pins one end to this Li-ion batteries or any safety is required .??

    ReplyDelete
    Replies
    1. Connect the Lap top battery terminal voltage to the charging input of a mobile phone via a suitable charging pin.

      The mobile phone internal circuit will safeguard its battery and will automatically cut off when it's fully charged.

      Do not connect the laptop battery directly to the cell phone battery, charge it inside a mobile phone as explained above.

      Delete
  4. ok thanks a lot for your help will try and tell you

    ReplyDelete
  5. I use a 3.7V L-ion 1000mA battery for a medical device... It also has a smaller 300mA battery (same voltage)..... However, the battery charger only charges a max of 700mA. The batteries don't hold a charge for very long.... Is there any ways to adjust the schematic to be switchable for the two battery types??

    ReplyDelete
    Replies
    1. You can use the same charger separately for both the batteries. you can make a simple LM317 current limiter circuit and use it in series with your existing charger output while using it for the lower rated batt.
      you may refer to the first diagram in the following link, calculate R1 as per the formula:

      http://homemadecircuitsandschematics.blogspot.in/2013/06/universal-high-watt-led-current-limiter.html

      Delete
  6. I have Li-ion battery (US18650GR), in 2 parallel 2 series. I want to charge them without remove each batteries. I also want to use them as a power bank. In other word, I want to charge and discharge the batteries with protection ( discharge min 2.9 v, charge max 4.2v each) and 5v output and it may not be used while charging. Thank you for your help.

    ReplyDelete
    Replies
    1. I am sorry have no idea how to charge li-ion batteries with series/parallel connections safely, so cannot provide correct info regarding it

      Delete
  7. What about circuit protection to each battery?
    Thank you

    ReplyDelete
  8. Please what circuit can I use in charging an 11.1v, 33.6Ah, 373w battery (TH-68110146)? It has Four wires. Red Positive and Black Negative (thick wires), yellow and green (thin wires).

    A D4146 or AOD4146 transistor blew out in the charging circuitry and I can't locate it in the store. Any help about a substitute?

    ReplyDelete
    Replies
    1. In the diagram it's clearly shown that the the circuit is meant for a 3.7v li-ion cell phone battery. The battery that you have connected is no way applicable with this circuit.
      use a LM338 charger circuit for your battery, I have plenty of these circuits in this bog, you can search them through the given search box.

      Delete
  9. what is the difference between using LM388 charger circuit and LM3622 charger circuit?

    ReplyDelete
  10. is there an alternative for the dta 143z transistor, preferably through-hole ?

    Thanks a lot
    André

    ReplyDelete
    Replies
    1. sorry, i do not have any reliable info regarding it.

      Delete
  11. Hi Mr Swagatham

    I am converting a cordless drill from Ni cad batteries to Lion battery with voltage rating of 13.2 volt
    battery pack.. I have gone through lot of circuits regarding Lion batteries charging methods regarding the constrain in LIon battery charging but most of them are prefering to go for balanced charging of Lion batteries if your are connecting in series i,e 3.6x3volts
    kindly help me out in designing a balanced charger circuit and posting on ur blog which would be great helpful from ur side

    Thanks & Regards
    Balaram

    ReplyDelete
    Replies
    1. Hi Balaram,

      We must go according to what is recommended, otherwise it could lead to overcharge or over discharge for some of the cells while the opposite for the others.

      I would suggest that you use a single SMF 12V battery instead of a battery pack for avoiding the hassles.

      Delete
  12. hi Swagatam, the switching of the J1 and J2 is supposed to be a manual procedure rite??

    ReplyDelete
    Replies
    1. hi yeshwanth, yes it's a manual operation through switches.

      Delete
  13. Hi Swagatam,

    May I know how to charge a li-ion four pack battery (14.8 volts), with an input of 12 voltsDC, using LM3622, based on your diagram above?

    ReplyDelete
    Replies
    1. Hi Vic,
      using the above circuit for a 12V to 14.8V application could be complex, it's better to go for a simple opamp based design with a boost converter instead.

      Delete
  14. Hi
    I'm looking in to replacing a Li-Ion battery in a garden powertool. It's a small one that contains a 3.6V 1300mAh cell. The charger cirguit is covered with a water tight coating, so it can't help me much.
    Do you think the system could handle a 3.7V 3000mAh replacement?
    Thanks in advance.

    ReplyDelete
    Replies
    1. Hi,
      yes the above circuit will be capable of charging a 3AH, both the PNP transistors will need to be mounted on a heatsink for optimal performance

      Delete

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Readers are advised to proceed with the construction of the presented circuits only after understanding the concepts from the core. Not adhering to this can lead to failures and frustrations.