🛠️ MAKER GUIDEApr 10, 2026•⏱️ 2 min read•🇳🇵 Tested in Nepal
Active Battery Balancer & Voltage Equalizer for 4S LiFePO4 / Li-ion Solar Banks
Protect expensive 12V 4S lithium and LiFePO4 solar storage packs by equalizing individual cell voltages during charging with automated resistive shunts and Arduino.
🛠️ BILL OF MATERIALS (BOM)
Required Hardware & Component Checklist
Curated components verified for this project. Check the items you need, adjust quantities, and add straight to cart:
Estimated Total (5/5 items):
NPR 2,710
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NPR 750
NPR 1,000
(NPR 250 ea)
NPR 240
(NPR 60 ea)
NPR 500
NPR 220
Active Battery Balancer & Voltage Equalizer for 4S LiFePO4 / Li-ion Solar Banks
Uneven cell resistance causes individual cells in a series lithium pack to overcharge while others lag behind. This balancer monitors all 4 individual cell nodes using Voltage Detection Modules and activates precision IRFZ44N MOSFET bleed shunts to equalize cell voltages within 10mV.
Hardware Bill of Materials (In Stock at Ghumti Pasal):
- Microcontroller: Arduino Nano V3.0 Solderless (Without Cable)
- Voltage Modules: 4x Voltage Detection Sensor Module 25V
- Bleed Switches: 4x IRF Z44N N-Channel Power MOSFET
- Telemetry Screen: 0.91 inch OLED module blue OLED 128X32 GND-VCC-SCL-SDA
- Regulator: LM2596 DC-DC 3A Step-Down Module
Circuit Pinout & Wiring Connections:
| Sensor / Balancing Channel | Arduino Nano Pin | Function / Description |
|---|---|---|
| Cell 1 Voltage Sense | Pin A0 | Measures Node 1 (0V - 3.65V) |
| Cell 2 Voltage Sense | Pin A1 | Measures Node 2 (3.65V - 7.30V) |
| Cell 3 Voltage Sense | Pin A2 | Measures Node 3 (7.30V - 10.95V) |
| Cell 4 Voltage Sense | Pin A3 | Measures Node 4 (10.95V - 14.60V) |
| MOSFET Gate 1 (Bleed 1) | Pin D5 (via 1kΩ Resistor) | Bleeds Cell 1 Energy via 10Ω 5W Resistor |
| MOSFET Gate 2 (Bleed 2) | Pin D6 (via 1kΩ Resistor) | Bleeds Cell 2 Energy via 10Ω 5W Resistor |
| MOSFET Gate 3 (Bleed 3) | Pin D9 (via 1kΩ Resistor) | Bleeds Cell 3 Energy via 10Ω 5W Resistor |
| MOSFET Gate 4 (Bleed 4) | Pin D10 (via 1kΩ Resistor) | Bleeds Cell 4 Energy via 10Ω 5W Resistor |
| 0.91" OLED SDA / SCL | Pin A4 / Pin A5 | I2C 4-Cell Voltage Matrix Display |
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