🔋 DIY Automatic Load On/Off Mini DC IPS Making at Home | LM317 Based Lead Acid Battery Charger

Are you looking for an easy way to build a mini DC IPS (Inverter Power Supply) with automatic load on/off functionality for a lead-acid battery? You're in the right place! In this post, I'll show you how to make your own DIY automatic mini DC inverter power supply using a LM317 voltage regulator, a relay, and a simple control circuit.

️ Required Components

To replicate this project, you'll need:

1. LM317 Voltage Regulator (U1)
2. Relay SRD-05VDC-SL-C (RELAY2)
3. Diodes (1N5399)
4. Electrolytic Capacitor (4700μF)
5. Resistors (1KΩ, 338Ω variable)
6. LED Indicators
7. Battery Connector
8. Load Connector
9. DC Jack (DC1)

The above schematic shows a simple, linear DC power control and charger system:

1. Input Voltage: Comes from a DC adapter via DC jack
2. LM317: Regulates output voltage for safe battery charging
3. Relay Control: Automatically disconnects the load when the voltage drops
4. LED Indicators: Show charging and load status
5. Protection Diodes: Prevent reverse polarity or feedback

To make your own PCB, download the provided Gerber file and upload it to any PCB fabrication service (like JLCPCB, PCBWay, or EasyEDA):

🔗 Download Gerber File (.zip)

This layout supports all components in a compact single-layer board, perfect for DIY enclosures.

This Mini IPS (Inverter Power Supply) circuit is perfect for small DIY power backup systems where you need to:

1. Charge a 12V lead-acid battery efficiently
2. Automatically switch loads ON/OFF based on voltage
3. Power up LED lights or other small devices during outages

1. Charging Mode:
2. The input DC power charges the battery through LM317.
3. RP1 (variable resistor) adjusts the charging voltage (ideally 13.6V–13.8V for 12V lead-acid batteries).
4. Load Control:
5. When the battery is fully charged and the voltage is stable, the relay connects the load automatically.
6. If the battery voltage drops below a certain threshold, the relay disconnects the load to protect the battery.
7. LED Indicators:
8. LED1 shows the charging status
9. LED2 shows the load connection status

Emergency lighting systems

Mini solar UPS backup

12V fan or light power supply

Small off-grid battery maintenance

Want to watch the full step-by-step guide with live testing? Subscribe to our YouTube channel for a Bangla DIY electronics tutorial series!

Always test with a multimeter before connecting a real battery.

Use heat sinks for LM317 if you’re drawing current above 1A.

Secure all connections properly to avoid loose contact.

This DIY Mini DC IPS circuit with automatic load switching is a great project for electronics enthusiasts who want a reliable power backup for small devices. With the included schematic diagram and Gerber file, you can make this project at home easily.

Don’t forget to share your builds or ask questions in the comments!