"This schematic is for a lead-acid battery charger circuit. I've set up this circuit, but it's only charging at about 15 milliamps. Can anyone help me troubleshoot this problem? By the way, all component values are according to the schematic, except I used a 13-volt transformer instead of a 15-volt one."

 

What output voltage are you getting?

 

I used a 13-volt transformer instead of a 15-volt one

Use this power adapter instead transformer X1 and diodes D1, D2.
Price $4.54, free delivery.

 

What output voltage are you getting?

"The circuit is designed to provide a 14-volt output. However, once the battery is connected, the circuit's output voltage is replaced by the battery's voltage."

 

hi alir,
The 13V transformer is the problem, a LM317 requires approx 3V across it in order work correctly.
Also a 0.7V drop across D3 is a problem.
E

 

Use this power adapter instead transformer X1 and diodes D1, D2.
Price $4.54, free delivery.
View attachment 333938

"Understood, I will incorporate these changes and report back with the findings."

 

Measure voltages at different points in the circuit and show us.

 

hi alir,
The 13V transformer is the problem, a LM317 requires approx 3V across it in order work correctly.
Also a 0.7V drop across D3 is a problem.
E

So you're saying I should completely remove diode D3 from the circuit?

 

hi alir,
No, I am saying it is adding to the problem of low voltage at the battery, when using a 13V transformer, when trying to draw a high battery charge current.
What are the details of the transformer VA rating and the battery type and AHr rating?
E

 

This is your basic battery charger circuit. Analyse this circuit to help you determine what is wrong with your circuit.



https://forum.allaboutcircuits.com/threads/lm317-battery-charger-circuit.149498/

 

hi alir,
No, I am saying it is adding to the problem of low voltage at the battery, when using a 13V transformer, when trying to draw a high battery charge current.
What are the details of the transformer VA rating and the battery type and AHr rating?
E

I'm using a 12-volt, 5-amp-hour battery and a 13-volt, 3-amp transformer. Would you be able to provide a circuit diagram that could replace this setup?

 

Hi,
Check this link for simple 12V charger circuits.
E
https://www.homemade-circuits.com/how-to-make-current-controlled-12-volt/

 

Hi,
Check this link for simple 12V charger circuits.
E
https://www.homemade-circuits.com/how-to-make-current-controlled-12-volt/

Thank you very much.

 

hi aril,
Please let us know the project progresses.
E

 

My sim shows you should be getting normal charging current even with a 13V transformer.
What are the voltages at LM317 pin3 and pin 2?

 

Per Cruts’ request, please also include the voltage in pin 1 of the LM317.
The reason is that the voltage difference between 2 and 1 should be 1.25 volts. If it isn’t, then the LM317 isn’t working.

 

Per Cruts’ request, please also include the voltage in pin 1 of the LM317.
The reason is that the voltage difference between 2 and 1 should be 1.25 volts. If it isn’t, then the LM317 isn’t working.

The voltage at pin 1 is 10.10 volts, and the voltage at pin 2 is 10.49 volts.

 

Per Cruts’ request, please also include the voltage in pin 1 of the LM317.
The reason is that the voltage difference between 2 and 1 should be 1.25 volts. If it isn’t, then the LM317 isn’t working.

The voltage at pin 1 is 10.10 volts, and the voltage at pin 2 is 10.49 volts.
Adjusting the potentiometer does not change the voltage at the pins.

 

Hi alir,
What is the voltage on pin #3?
E

 

Hi alir,
What is the voltage on pin #3?
E

The voltage at pin 3 is 13 volts