Battery charger circuit using LM317.
Description.
Here is a simple but effective battery charger circuit using IC LM 317.The circuit can be used to charge 12Vlead acid batteries.The circuit is very simple and can be easily assembled on a general purpose PCB.
The heart of the circuit is IC LM 317 ,which is an adjustable voltage regulator IC.The pin 1 of the IC is the control pin which is used to control the charging voltage.The pin 2 is the output pin at which the charging voltage appears.The pin 3 is the input pin to which the regulated DC supply is given.
The charging voltage and current is controlled by the Transistor Q1,resistor R1 and POT R5.when the battery is first connected to the charging terminals ,the current through R1 increases.This in turn increases the current and voltage from LM 317.When the battery is fully charged the charger reduces the charging current and the battery will be charged in the trickle charging mode.
Circuit diagram with Parts list.
Notes.
- The input voltage to the circuit must be atleast 3V higher than the expected output voltage.LM 317 dissipates around 3V during its operation.Here I used 18V DC as the input.
- The charging voltage can be set by using the POT R5.
- The LM 317 must be mounted on a heat sink.
- All capacitors must be rated atleast 25V.
- You can use crocodile clips for connecting the battery to the charger.
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I’m student,i need your assistance by sending all the information materials i need for my project topic which Design and construction of an Automatic 12V car battery charger with a digital voltmeter display to me.your website is best website for all learners.
is it that we can use only acid lead batteries to charge? can we put like the mobile battery of 3.7 volts?
Hi Edgardo the aove circuit can be used with little modification. Raise R2 to 1.8K R5 to 470 ohms and raise the input voltage to 28to 30volt DC. Use a good heat sink for LM317.
Hi Anuj The above circuit can be used with modifications, kindly give the specification of your battery for the solution.
can i charge the 3v battery from the 9v battery.
Hi Seetharaman, Good day..
Can there be a circuit for a battery charger using LM317 by 24 volts lead acid batteries?
Thanks.
Edgardo
Hi NFERMITO the current is limited to 1.1amp (the ICs current limiting factor is 1.5amps even without external limiting circuit) hence the wattage dissipation is just 0.35watts with 1.1amp, hence 1/2 watt is sufficient at the most you can use 1watt resistance.
R1 is 5W according to another internet site. Take care of it.
Hi, am a student who needs help on is project to Design a constant power battery charger with inherent soft-switching.
Hi Lao without battery set the output voltage at 13.8volt with pot for 12 volt battery for normal charge. set the voltage at 14.5 volt for boost charge. as the terminal voltage trying to reach the set voltage the charging current will fall down automatically. this setting will suit only 12volt lead acid batteries.
Hi, how can i set the set current? how can i control the current during charging and fully charge?
Hi Gan initially the battery will be on constant cuurrent mode and then bellow the set current mode will be charged on constant voltage mode. once the terminal voltages starts falling down due to self discharge of the battery the charger will start topping up the battery till such time its terminal voltage reaches the preset voltage. the process continues.
Hi,
I just want to confirm that which component will trigger the trickle charging mode? Is it because of the transistor is experiencing cut off then the battery will no longer be charged?
Hi,
I am charging a 7AH-12v lead-acid bat with a solar cell and not using the transistor and the R1(.56 Ohm).(i.e. using only LM317 and two register to set the o/p voltage to 14.4v in no-load condition). My question is why we need the R1 ?
Thanks,
Sanjib
I’m student,i need your assistance by sending all the information materials i need for my project topic which Design and construction of an Automatic 12V car battery charger with a digital voltmeter display to me.your website is best website for all learners.
I HAVE LOST MY CAR CENTRAL LOCKING REMOTE,IS THEIR ANY CIRCUIT TO UNLOCK IT.BEFORE SOMEONES TRIES TO STEAL IT.
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pls help me with a single phase automatic change over switch circuit diagram & the full write up,pls it’s algent,i need it 4 a project.2 my e-mail aaabdul86@yahoo.com
pls help me with a single phase automatic change over switch circuit diagram & the full write up,pls it’s algent,i need it 4 a project
http://forum.allaboutcircuits.com/showthread.php?t=23063
i want to increase charging current to 120 ma pls tell me the modification
LM 317 can be used for charging SMF batteries
Solution: Put a diode at the positive pole just before the battery connection.
I want to make a Exit light,but i face a problem from a 6V batery charge and also i want to exit light all time lighting by ac 220v to dc adapter from bc and battery charge but when ac is off then battery backup and led light is lighting.please circuit diagram solve
I have some questions:
Is there any problem if I use LM317-Charger circuit for charging Sealed Lead Acid batteries?
BC140 is not available, what are the replacements I can use?
Thanks