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Battery Chargers

 A battery charger, or recharger, is an equipment accustomed to supply electric power into a supplementary cell or rechargeable battery pack by pressuring an electric current into it.

I have presented many thoroughly researched battery charging concepts which promise not only the best possible way of charging your battery but also equipped to implement the same with utmost care and safety.

There are plenty of choices you can get while designing your own battery charger circuit as per your specific needs and battery specs. For more detailed information regarding the various types of automatic and semi automatic battery charger circuits, please select the one as per your requirement from the following from the range:

      90 comments:

      1. Hello Mr Swagatam I am a member and a keen follower.I use this unit to backup my laptop but it is bad Can you help me with the circuit that will charge these battery. It has the following labels
        Model:TH-68110146
        working voltage-11.1volt
        Capacity- 33.6A
        Power-373W
        The battery has 48 pcs of cells. It has four wire coming out and is labeled with the following output voltages
        red black wire= 11.5v
        yellow black= 3.8v
        green black= 7.7v
        The request here is, I need the circuit that will charge the cells, the main charging circuit of the unit has burnt beyond repairs but the cells are good

        ReplyDelete
        Replies
        1. Hi Rabiu,

          Would be able to find the AH ratings of the individual cells, otherwise it would be difficult to figure out the safe charge levels for them..

          Delete
        2. ....i mean, please find out the AH ratings for the different cells, that would help me to design a correctly dimensioned supplies for them

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      2. Hi Swagatam

        First of all, kindly increase the headings of your blog.

        Secondly, all the members/followers should post their comments/requirements/questions under related heading. This will enable to look for a specific post easily.

        My question......Suppose a project needs three different voltages, say 24V, 9V and 3V. If we have a 24v supply, we can get 9V/3V thru V/Reg ICs or thru 2 sets of potential divider. I just want to know which of these two approaches is more practical and why? What are the disadvantages of the other.

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        Replies
        1. Hi Abu-Hafss,

          I agree with your suggestion, I'll do it as soon as I get some free time.

          As far as your question goes, a voltage divider is used with inputs where the current requirement is negligibly small, because a voltage divider would provide current in mA.

          Whereas a 78XX type regulator would provide voltage regulation along with high magnitudes of current....so it depends on the application needs and conditions, if it's low current then a voltage divider would work otherwise it's better to go for standard VR chips.

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        2. Okay, understood.

          And when do we use a zener for voltage regulation in contrast to a 78XX regulator?

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        3. zener may be used for achieving low current constant voltage references.

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      3. hi sir,...

        like this

        help me send cicuit pcb and layout?

        thanks sir

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      4. Hi Swagatam

        I want to share the strange behavior of a power supply circuit which I assembled from scrap components.

        Transformer 220v >>> 24v (100-200mA)
        Rectifiers 1N4007
        Capacitor 3300µF/30V and 2200µF/35V

        The transformer output is showing 23VAC.
        After rectification, if 3300µF/30V is connected, I get 33VDC.
        And if 2200µF/35V is connected, I get more than 36VDC.

        How can we get more voltages than the output of the transformer?

        ReplyDelete
        Replies
        1. Hi Abu-Hafss,

          As you may be knowing that the AC when measured shows the RMS value, once it gets rectified and a filter cap is connected, the stored charge compensates the ripple gaps and also the exponential nature of the vlotage, and generates a voltage almost equal to the input peak voltage, and that's the reason for the increased voltage at the output.

          Delete
        2. Hi Swagatam

          I think you mistook the output voltage.

          The input peak voltage is 23V (before rectification)
          and the output is 33V or 37V (after rectification/filtration).

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        3. I am getting more than 30v instead of 24v.

          Do I need to deploy a 24 zener ?

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        4. Hi Abu-Hafss,

          The 23V is the RMS value or the average value, not the peak value...

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        5. ...a 7824 IC would be a better option.

          Delete
      5. Need a simple circuit in parallel with a battery charger and a 12v battery to indicate when the battery charger is "on". Thus, a circuit in parallel with a battery charger and a battery which will light an LED (7ma 1.9V) when the voltage exceeds 13.5 or so. Maximum voltage from the charger is 18V.

        ReplyDelete
        Replies
        1. you can try the first circuit from this article:

          http://homemadecircuitsandschematics.blogspot.in/2011/12/how-to-make-simple-low-battery-voltage.html

          Swap pin3 and pin2 positions of the IC with each other.

          Apply 13.5V and adjust the preset such that the LED just lights up at 13.5V.

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        2. Thanks so much. I'll give it a try.

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        3. Back again - would a Microchip TC54 also work and require less components?

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        4. may be it can be used, although i am not sure how it can be used with 14V supplies?

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        5. Ok, thanks for your comment. Unless you can suggest a schematic, I'll proceed with the 741.
          Thanks again.

          Delete
      6. Dear sir, I've read about the Supercapacitor by the teenage girl in the internet, is there any simple diy to make a phone charger with it.? and what is your comment/suggestion regarding these if any.. thank you

        ReplyDelete
        Replies
        1. Dear Kaunisiapa,

          I'll do some research about it and try to revert soon.

          Delete
        2. hello sir would you plz advise me a circuit to charge 3 4v batteries connected in series ( giving 12 v ) with a 3-5 volt charger I m new to electronics!!!!

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        3. hello Mujahid, you will need a boost circuit for that. Please Goggle "IC555 boost charger circuit" and you can use it with your 5V charer to get a 12V output

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      7. Hi Swagatam,

        I am recent follower of your posts and its very impressive.

        As a part of my mini project I need to convert a "Water bath heater" powered by a 12v/5A supply to a rechargeable battery system supply. Is this possible?

        Hope you hear from you soon,

        Thank you.

        ReplyDelete
        Replies
        1. Hi Jithin,

          you can use a 12V smf battery for powering the heater directly, the AH rating can be anywhere from 10AH to 200AH....AH rating will decide the backup time only, and will not create any safety issues as long as the battery voltage matches the load voltage (heater voltage).

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      8. hi swagatam, i recently bought a UPS battery which is 12v 7AH lead acid for my robot. Now i want a charger for that. I don't want an automatic charger, just a simple charger with an indicator to show that the battery is full......Also the input should be from 220v wall outlet. do you have a circuit for that.....??

        ReplyDelete
        Replies
        1. Hi Himanshu,

          You can simply charge it through a 12V/1amp transformer after rectifying and filtering the voltage with a bridge rectifier and a capacitor.
          For indication use a 1amp ammeter in series with the positive connection of the power supply with the battery.

          Initially the meter will show full deflection, as the battery is charged the deflection will slowly move toward zero and finally settle to zero once the battery attains a full charge.

          Delete
        2. As you told me i bought a 12v/1amp transformer but it gives me 14v as output and after rectifying it i get 19v as output. i am using 1N4007 diodes and a 1000uF capacitor to rectify the voltage. Can i still use this circuit to charge my battery. If not please suggest any changes.

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        3. it should show 12V or 12.5V max, if it's showing 14V either the trafo is not wound correctly or your mains has above 250V input.

          after rectification it must reach not above 16V.

          but anyway you can use it for your 12v 7ah, it would drop to the correct level automatically.

          Delete
      9. hello sir!..i need your help please. i got a project to do as my assignment..my project is a simple buck converter. the problem is i use n-ch mosfet irf640, i simulated it in proteus. it worked well, but when i test it on breadboard i got a low output voltage. my power supply is 30v, and output is varried according to dutycycle from arduino, frequency is 100khz. i try to use resistor from 1k to 10k at gate pin to ground, and try to change the frequency from 1k to 100khz, i use inductor 100uh, and 100uf as current and voltage filter.. i got only 4-5v max output voltage at fully duty cycle, 0.2-0.7v at zero duty cycle. it seem that mosfet is not fully on or off. but when i tauch my figer on gate pin i got fully output voltage. even i leave gate unconnected. it is still no zero.. please can u help me?

        ReplyDelete
        Replies
        1. hello seok, with a digital multimeter check the voltage at the gate of the mosfet, and also check frequency at that point....let me know about these, I will try to figure out the fault.

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      10. thank u sir! for your reply..as i measured it..it is the same to the output of pwm from the arduino(around 5v at 100%duty cycle) the frequency i use is 100khz. i have tried to vary the frequency but the result is the same.. n i try to replace pwm from my arduino by using pwm generator. but the result is still the same.

        ReplyDelete
        Replies
        1. Try using BJT stage in between the arduino output and the mosfet gate, this will enable amplifying the 5V to 12V(supply) and help the mosfets to conduct more current.

          I hope you know how to configure this?

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      11. i try to use with other fet or two transistor as dalington, or transister with fet. the result is the same..i was very wonder.. sir! can u implement a work buck converter circuit for me with input 30v 3a f=100khz with any switch for me..i m tired to test my circuit again and again..

        ReplyDelete
        Replies
        1. you can try the following design:

          http://homemadecircuitsandschematics.blogspot.in/2014/06/solar-panel-buck-converter-circuit-with.html

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        2. sir, I have a 20v DC supply. I need a 5v 3A DC from it. can i obtain this with LM7805 and pass transistor? or is there any other way to get 5v 3A ? pls help me

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        3. Sreekumar, yes it's the easiest way to go, using a 7805 IC with an outboard BJT to support the extra amps.

          More details can be found here:

          http://easy-electronic-circuits.blogspot.in/2012/03/deriving-high-current-from-7805-7812.html

          Delete
      12. good day sir,
        I need a portable rechargeable battery that capable of generating around 100-120 w sir, do you have an available circuit for that sir? or can you suggest a schematic diagram for it sir. Thank you so much sir I just need it for my project at school sir :)

        ReplyDelete
        Replies
        1. good day Leen, you can try the second circuit shown in the following link:

          http://homemadecircuitsandschematics.blogspot.in/2011/12/how-to-make-simple-low-battery-voltage.html

          Use any battery as per your specs in the design and enclose the system inside a box for completing the design. The input will need to be integrated via a suitable SMPS adapter unit.

          Delete
      13. Hi sir, can u please provide a circuit in order to charge 4 li-ion batteries in series using multi stage CONSTANT CURRENT source?

        ReplyDelete
        Replies
        1. Hi Tom,

          You can use the second circuit from this article for your need:

          http://homemadecircuitsandschematics.blogspot.in/2012/07/make-6v-4ah-automatic-battery-charger.html

          Delete
      14. Well done sir, I made this circuit for charging my 45AH lead acid battery but its output doesn't go up to 14V instead it stpps at 13.4V when varying the 10K pot so I don't know the problem, is it the 1K resistor on series with the 10K pot or not? because when I measure the EMF of the at around 6pm, I only get 12V alway everyday not 13.V ,thanks.

        ReplyDelete
        Replies
        1. thanks kakooza, use a 22k pot and check the results

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      15. sir i would like to make an auto turn of cellphone charger with 220v input and 5v .7mA output any suggestions?

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      16. hi sir, i have a project and i need to make an auto cut off cellphone charger with input 220v and an output of 5v .750mA any suggestions?

        ReplyDelete
      17. hi swagatam i found this circuit. please help me what changes i should do to make this to have an input of 220v 60hertz and an output of 5v and 700mA

        ReplyDelete
        Replies
        1. Hi hannah, you can use a standard 12V AC/DC adapter and use the second circuit from the following link with it:

          http://www.homemade-circuits.com/2012/07/make-6v-4ah-automatic-battery-charger.html

          the shown battery points can be then used for charging the cell phone with an auto cut off feature


          by the way all celi phones have an in-built sophisticated auto-cut off circuitry...so an external feature is just unnecessary.

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        2. Hi Swa. Is necessary to have a battery on continuous trickle charge the entire day. Would once a day suffice or is this not good for the life of the battery.
          I'm thinking on the the Line of having the inverter switched off during the day only coming on at predetermined times to avoid it working during the day when we do not require backup power.
          Thank U.

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        3. Also the inverter does not charge higher than 13.62v . For a 12v 102ah deep cycle battery should it be brought to 14v which I've read is the fully charged state. The battery is reading 12.63v.
          Thank u

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        4. Trickle charge is necessary only if the battery is left unattended for a long period of time otherwise it's not necessary.

          if the battery is not charging above 13.6V the problem could be in the charger voltage setting or may the battery is damaged internally and not accepting optimal charge, it can be either of the two.

          once the charger input is removed, the battery voltage will eventually settle down to around 13V, even if it's been charged at the 14V level.

          Delete
      18. Hello friend,
        I want simple 3.7v 2000 or 2000 and above ma battery charger circuit with auto full charge cutoff, with led indicator circuit. bcoz I am using now 3.7v battery charger circuit(circuit from 18650 power bank circuit) but its taking too much time to recharge my battery ex: more then 5hrs. I want to charge my battery within 2hrs. Thank you.

        ReplyDelete
        Replies
        1. Hello friend, you can try any of the circuits presented in the following article:

          http://www.homemade-circuits.com/2012/07/make-6v-4ah-automatic-battery-charger.html

          make sure to adjust the voltage to 4.2V for your application

          Delete
      19. Hello sir I need a simple automatic AVR for a diesel generator
        It is used to operate 4 fuel pumps on a refill station but now the one we use is weak & now operates two low power pumps, just help sir, thanks.

        ReplyDelete
        Replies
        1. Kakooza, please provide a detailed info regarding your requirement....

          Delete
      20. Hello Sir, your website is truly a pleasure to read and thank you for publishing your work. I am building a charger for a electric scooter with lifepo4 battery system. The charger is rated between 52-54V and able to output up to 10A of current. Do you have any suggestions? Thank you sir.

        ReplyDelete
        Replies
        1. Thanks Jon, I think you can try the first circuit from the following article, it will suit your application need:

          http://www.homemade-circuits.com/2012/08/make-this-48v-automatic-battery-charger.html

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        2. Thank you for the sir. Thanks again for posting your work!

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      21. sir iam john i really very interested in electronics so that i need your help about my final year project about the circuit diagram and its detail of detection of brocken conductor for overhead lines and i tried to do it but somehow post from Tanzania

        ReplyDelete
        Replies
        1. You can try the following design and modify it accordingly for your application need:

          http://www.homemade-circuits.com/2011/12/how-to-make-non-contact-ac-mains-phase.html

          Delete
      22. hi sir, recently my UPS battery 12V 7AH died on me, its bcoz we get sub-standard battery quality here, now i have got a lot of Li-ion batteries i.e. 18650, with me; is it possible that i can charge these 3x18650 combined in series and used as UPS battery? also can i use the UPS battery charger to charge the 18650 battery; if not i need to build another circuit for these battery. thanks in advance.

        ReplyDelete
        Replies
        1. Hi Tom, you can replace it without doing any change, there's no harm in doing so....but is the AH rating of the Li-ion batts 7AH? otherwise the back up time of the UPS might get affected

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      23. Hi sir can you explain, cpu ATX power supply to charging automobile battery

        ReplyDelete
      24. hi hello mr. swagatam im here again..can ask again? sir I have made a power bank, my project was working but the problem is the percentage of my batt is not increasing. what do you think is the problem sir? I am using a 9 pcs.of batt in series..batt. name EXL Ni-MH AA1500mAh 1.2V

        ReplyDelete
        Replies
        1. Hi Mark, which battery did you charge with your power bank? please remember that the client battery should have much lower AH and voltage specs than the master battery for getting optimally charged.

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      25. Good Day Mr Genius. please I need your help on one of my power supply. I need a circuit for step down transformerless 220VAC to 110VAC. Thanks a million.

        ReplyDelete
        Replies
        1. Good day Elvis, sorry that is just not possible.

          Delete
      26. hello sir, i need a Li-MH circuit for charging AA and AAA cells with all kinds of indicator circuit and for safe use by any one please help me in suggesting it ..

        ReplyDelete
        Replies
        1. Hello Virendra,

          you can try the second circuit from this link

          http://www.homemade-circuits.com/2012/07/make-6v-4ah-automatic-battery-charger.html

          Delete
      27. hi sir,
        i have dynamo and it is powered by a mechanisms when a car goes over it. the dynamo produced a max of output voltage of 25v. i want to use this output voltage to charge a 12v car battery and simultaneously give to a power inverter to power some appliances. sir can this be achieved and what is the circuit for the same??

        ReplyDelete
        Replies
        1. Shramik, you can try the following circuit

          http://www.homemade-circuits.com/2014/05/generating-electricity-from-road-speed.html

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        2. thank you so much sir,
          sir once the battery is charged can i use the battery simultaneously for powering a power inverter??

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        3. yes that's possible, but only after the battery is fully charged

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        4. sir
          but how to ensure that only the battery is powering the inverter and not the dynamo??
          as i want the battery to continuously power the inverter output and simultaneously the dynamo should charge the battery.

          Delete
        5. Sharmik, you will need to employ a relay changeover stage which should be designed to trigger in the inverter mode as soon as the battery is fully charged.

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        6. sir,
          can i get full circuit for my project.
          in which the dynamo charges the battery and as soon as the battery is full the inverter can be turned on.
          also sir, is there any way i can keep my inveter on all the time either from the battery or the dynamo?

          Delete
        7. Shramik, you can try the second circuit from this article

          http://www.homemade-circuits.com/2011/12/how-to-make-simple-low-battery-voltage.html

          connect the inverter positive supply with the N/O of the relay and the negative with the battery negative.

          Delete
        8. thank you sir,
          but this circuit will only turn power inverter on when the battery is fully charged??
          sir my project is such that, the inverter should be on continuously whether the dynamo is running or not.
          sir this can be done by a circuit in which, the power inverter is powered most of the time by dynamo and also dynamo simultaneously charges the battery and when the dynamo is not running, power inverter input switches to battery output
          so first a circuit which charges a battery.
          second a circuit which powers the inverter through the dynamo.
          third a circuit which switches the power inverter input between dynamo output and battery output.

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        9. In that case you can try the following circuit

          http://www.homemade-circuits.com/2013/03/simple-dc-ups-circuit-for-modemrouter.html

          or you can also try the following concepts

          http://www.homemade-circuits.com/2015/11/redundant-ups-circuit.html

          here the 14V input could be replaced with battery, the "alternative power" with dynamo and the N/O contact of the relay should be joined with D2 cathode.

          Delete
      28. Sir,
        I own a lenovo laptop,its adapter(65W 19v 3.42A) has gone bad(it can power the laptop but could not charge the battery).On travelling in train it often damages the power board present in the coach when connected.What could be the cause?On opening the adapter case and seeing pcb all seems ok.I thought that the capacitors could be faulty but on seeing it ,it seems ok.What could be the cause.

        ReplyDelete
        Replies
        1. Nishant, if it is damaging the board then definitely it is not OK....you should check the voltage with a meter to confirm its condition....
          you are saying it's not supplying enough current for the laptop and for charging the battery, that is contradicting your second statement....because if it is not capable of supplying or drawing sufficient current then it shouldn't be capable of damaging the board either?

          a proper analysis using a DMM will be required to confirm its actual status...

          Delete
      29. Hi Swagatam, it is I again calling on your expertise. Which of all the battery charger circuits that you have on your site would you recommend to use for charging 12V 7.2Ah SLA batteries.
        Regards
        Geoff

        ReplyDelete
        Replies
        1. Hi Geoff, you can try the last circuit from the following article:

          http://www.homemade-circuits.com/2012/07/make-6v-4ah-automatic-battery-charger.html

          Delete
        2. http://www.homemade-circuits.com/2012/07/make-6v-4ah-automatic-battery-charger.html

          Delete
      30. Hai sir,
        U helping me lot sir....

        Few doubts in indicator method...
        I'm using 12 7ah battery ....
        If the battery voltage 11v will come..the led will indicate and buzzer will make sound....
        Circuit I'm using
        Bc547 2
        1k resistor 2
        11v zener 1
        11v zener cathode connected in battery + side..anode connected in 1k resistor...1k resistor connected in transistor base,, emitter negaive,,,
        2 transistor emitter negative ,collector led,,,base is connected with 1k resistor in postive ...now the 1transistor collector directly connected to 2transistor base...
        Circuit is working well...
        But prblm is when voltage 12.20 itself indicating low...
        What i want to do...
        I need to change
        Resistor value ?
        Zener value ?
        ....
        When 11v reaches the led need to indiacte sir..
        Pls guide me sir

        ReplyDelete
        Replies
        1. Kesava, you can try connecting a 10K preset across base emitter of the tramsistor and adjust this preset to achieve the required threshold indication.

          Delete
      31. Hello Swagatam Majumdar, good afternoon to you and how's your end so far?
        Please i need your help and i have been following you for some time now, please i want to create a battery charger for 12v 200ah battery and 24v 200ah battery charger, with low voltage and high voltage cut off circuit. I've tried some of you circuit i saw on your blog but some how, i guess i was just lucky to build a charger but the low voltage and high voltage cutoff part is not working as perfectly as i want, please is there any help you can render to me with the circuit or where you can refer me to.
        Thanks for your help in advance Joshua

        ReplyDelete
        Replies
        1. Hello joshua, if you learn how to adjust an opamp comparator then it would be matter just 2 minutes to get the adjustments done accurately for the mentioned battery charger circuits, however the results will also largely depend on the quality of the parts, especially the opamp and the presets....if these are not good then the results might get severely affected.

          I can suggest you a couple of articles which you can try, these are easier to set than the usual single opamp circuits:

          http://www.homemade-circuits.com/2017/01/universal-battery-charger-circuit.html

          http://www.homemade-circuits.com/2016/05/opamp-low-high-battery-charger.html

          let me know if you have any difficulty with these concepts...

          Delete

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