# The most lead-acid battery charger circuit by LM317

When you want to build the lead-acid battery charger project for 6V battery or 12V. Although there are many methods to choose from. I like using IC LM317 Because easy to use, with minimal equipment. Cheap and good. Today, I try to collection ideas for the battery charger circuit. This is just part one.

*** Note: Though This project is good but it may difficut to build and expensive. I love this projects better : Simple auto cut off 12V battery charger

There are 4 circuits, as follows.

### 1. The universal battery charger using Lm317

Here comes very simple idea is the universal battery charger circuit.
When, an input power is applied to the circuit.
The SCR1 (Silicon controlled rectifier) turn off, then not has a bias current path to ground.

The LM317 acts as a current regulator, It is connected to the battery thought a one way diode D1, limiting resistor R1, and a bias resistor R2.
The D1 prevents the circuit from battery discharging, when the power out off from this circuit.
As the battery charges, the voltage across A point potentiometer R5 and some point rises, to turn on the SCR1.
Then current from the regulator LM317 can flow to ground, so now the IC1 is in functions the voltage-regulating mode.
The R6 be used to control the output voltage.
When the SCR1 turn on, it also provides LED1 through R3 with a path to ground.
But when LED1 is on, this circuit is in the voltage-regulating mode, while LED1 is off to be in the current-regulating mode.

### 2. 6V or 12V lead acid battery charger using LM317

This circuit be lead acid battery charger again interesting circuit, Because it can charger get both of 12V sizes and 6V. By change with switch only and this circuit charging with current about 1Amp. When see the circuit you will think us uses integrated number highly popular circuit be LM317K again. By when you Close SW1 make can charger battery 6V get. Which have voltage come out about 7 Volt. But enough Open SW1 as a result use charging battery 12 V get. Which give volt come out about 14Volt supposing that you use battery 6V 10Ah take time charging current 10 long ago hour. The diode D3 and D4 help protect voltage turn back from battery get. The detail is other see in the circuit.

Note: Or you can use this : Automatic Battery Charger 6V-12V with Relay cut off by LM324 as well.

### 3. 12V lead acid battery charger by LM317K

Today a close friend visits tell want Dry cell lead acid battery charger circuit 12V 7.5hA sizes. In model to are simple and economize with. I then advise this circuit try build see. By use the integrated circuit voltage regulator the number is highly popular be , LM317K. This circuit has the principle is simple be heal level voltage be stable 13.5 Volt. Because battery must use voltage tall more then charger get follow want.

Which battery of a friend must use current 1A take time charging about 8 hour then will have the electric energy with full speed ahead. The detail is other , see in the circuit. More information

### 4. Automatic Charger and Full charged indicator using LM317K-TL431

This is circuit Automatic Charger and Full charged indicator. For 24V batteries it can charger with current be stable about 1.5A and have voltage output 27Volt with integrated number circuit LM317K. When the battery has had full already , as a result will cut the work. There is a tube LED show the work with use integrated number circuit LT431 perform check the level , voltage battery and systematically protect short circuit with IC LM317. Unless D2 perform protect wasp a pole battery wrong as well. The IC1 should hold heat sink with. The detail is other , see in the circuit.

## 25 thoughts on “The most lead-acid battery charger circuit by LM317”

1. mark krawczuk says:

hi, can i leave this charger permanetly on the sla battery ? if not what changes would i have to make to do so ?

2. Vinod says:

“The universal battery charger using Lm317”
Please explain that this charger is automatic or not. By automatic, i just mean that when battery voltage reaches a particular level, this charger will be off. and when the battery voltage reduces to a particular limit charger will starts charging. And 2 LEDs are indicating these two states.

3. patrick vaz says:

Dear Sir,

Could you please help me with a circuit for 6v 12v automatic battery charger using 0-15v 5amps transformer, LM338 IC & ammeter and voltmeter etc (like a professional)

regards
Patrick

4. Mark says:

Hi there,

I built “12V lead acid battery charger by LM317K” and it’s working, but can someone explain me what does that GREEN Led, indicates full charged battery?

Thanks

5. Please can you explain why a power supply 12.5V DC stabilizer can not be use as batery chargerfor a sealed lead asid type battery?
Thank you Sarantis

6. Please can you explain why a 12.5 V dc power supply stabilizer can not be used as a battery charcher for a sealed lead acid type of battery?
Thanks Sarantis

7. Chris says:

No sarantis a 12.5 V dc power supply stabilizer can’t be used.That is becase you.ll need more voltage than 12 volts to charge a battery ,about 13,5-14,5 volts.

8. ismail Abdallah says:

Dear Sir

I would like to ask you about the DC output current from the battery charger to charge 2 batteries (12v/250 AH )
the charger 24v-10A enough for this operation
Regards,

Ismail Abdallah
B.S.C electrical engineering

9. Respected sir, Please tell me the value & power of used component in The universal battery charger using Lm317. I Like this & this is very useful.
Thank You.

10. mahalakshmi says:

sir i have a doubt.l d charger turn off wen it is fully charged and how this happens

11. thamjid says:

i have an IC named as LM317T. can i use this instead of LM317K?

12. sanni says:

Pls where can I get a detailed video of building these circuits, its not too straight forward for my level. Or can I get a more detailed explanation. Thanks

13. What values are you using for the universal battery charger using Lm317 ?

14. Teja says:

I have 6v 4.5ah old battery it shows 1.5v in multi meter. can i charge the battery..?
I have
out put 10v(10.9v) dc adaptor can i use
to charge the battery..?
I have another old
transformer(from old fm radio 1990) with center tapped it shots 5.5v ac and
0.02v ac . What do i do to charge the
battery..?

15. didier nsenga says:

what is role of ic lm 317 k in lead acid battery charger?

16. Apiece says:

I want to build the simple 6V or 12V charger for Lead Acid battery that must give an output voltage of 13.75V for charging the 12V battery. My circuit has the LM317K voltage regulator with R1=220 and R2=2.2k and I’m using a 220V/15V, 3A transformer as shown above. The explanation on the LM317T says that Vin must be at least 2.5 volts greater than the required output voltage to power the regulator. Is it possible then for my design to give out 13.75V., since 15V – 13.75V is just 1.25V which is clearly less than 2.5V ? I ask because the rms 15VAC secondary output of the transformer will also give approximately 15VDC from the full bridge rectifier.
I really want to build a simple but efficient dual purpose 6V or 12V charger, but it seems to me, from my question above, that this charger would be only efficient for 6V but NOT for 12V.

17. Hi, Apiece
You are correct.
I can charge 12v battery by 13.8v dc voltage.

18. Apiece says:

For the circuit 2 above, 6V or 12V Lead Acid battery charger, what other diode other than the MBR1545 in the circuit can I use? Pls give me similar/equivalent diode to that MBR1545 because I couldn’t get it in my locality. By the way what is the use of those MBR1545 in the circuit 2 above?
Thanks.

19. Hi, Apiece
I am sorry , I not test this circuit.

But I think we can use any diode as power current output.
You can use 1N5402 or 3A 200V diode for output current maximum 3A.

If have results any please share us.

20. I want to make 100ah 2 volts sla battery charger please give me

21. hi..
i want to make a charger in automotive application for 12V input and 5V, 1A output please provide me a circuit diagram but that diagram should have protection like, over voltage, short circuit,EMI/EMC, ESD, i/p surge, over load.

22. aza says: