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DIY Mini Rechargeable Power Supply with 3.7V Li-ion Battery Pack for Unlimited Energy

Intermediate

ANALOG / DISCRETE

₹500 – ₹1,500

3 – 6 Hours

Partial Kit

DIY Mini Rechargeable Power Supply with 3.7V Li-ion Battery Pack for Unlimited Energy

A robust, compact and hand-held mini rechargeable power supply delivering 9.2V, 5V, and 3.3V outputs powered by a single 3.7V Li-ion battery pack.

Originally published on ElectronicsForU

View original tutorial

Parts You'll Need

This project is sourced from another site, not written by us — this list is our best match of their components against what we stock, not a verified bill of materials. Always check the original blog (linked above) for the actual parts list before buying.

MB102 Adjustable Breadboard Power Supply Module (3.3V & 5V) for Arduino & Raspberry Pi Rs. 139.00
10pcs 5mm RED Diffused Light Emitting Diodes - LEDs Set Rs. 39.00
10pcs - 220 ohm 1/4 W Resistor Set Rs. 39.00
400 Points Mini Solderless Prototype PCB Breadboard High Quality Rs. 89.00
Jumper Wire 10 Pin Male To Male 20cm Rs. 45.00
Jumper Wire 10 Pin Male To Female 20cm Rs. 45.00

Selected: Rs. 0.00

This list includes a generic resistor set as a placeholder — it is not matched to the exact value or part number this circuit needs. The correct one is specified on the original source page linked above; check it before buying.

We don't carry yet: AA / AAA Battery + Holder
Header Pins / Terminals / Connectors
Capacitors
Voltage Regulator IC (7805 / LM317 / 1117)

Browse all components

How It Works

This DIY mini rechargeable power supply takes input energy from a standard USB connector or a DC input jack and manages it using the BQ24074 charger IC. The BQ24074 is responsible for safely charging the connected 3.7V Li-ion battery pack while simultaneously powering any connected system loads. The circuit relies on a network of support components including resistors and capacitors to stabilize voltages, filter out electrical noise, and set proper current limits. Once the 3.7V Li-ion battery pack is charged, voltage regulators and DC-DC boost or buck conversion stages step the nominal 3.7V up or down to deliver multiple stable output rails—specifically 9.2V, 5V, and 3.3V—making the power supply versatile for powering different microcontrollers, sensors, and communication systems like Li-Fi setups. Additionally, onboard LEDs are wired in through current-limiting resistors to serve as visual status indicators, showing whether power is active or charging is in progress.

Why Build This

Build a reliable, portable power bank capable of supplying 9.2V, 5V, and 3.3V rails for field testing microcontrollers and sensors.

Create a self-contained power source for mobile electronics and emergency mini torch light applications.

Gain practical experience designing power management circuits using dedicated charging ICs and battery packs.

Real-World Application

Portable power bank for mobile devices, field testing power supply for microcontrollers and sensors, emergency mini torch light.

Skills You'll Learn

Li-ion battery charging management

power supply regulation

DC-DC voltage conversion

schematic interpretation

circuit protection design

Safety Precautions

Li-ion batteries are sensitive to charging voltage and current; ensure proper management IC connections and avoid short-circuiting the battery pack.

Technology Tags

LI-ION BATTERY

BQ24074

POWER MANAGEMENT

DC-DC CONVERTER

USB CHARGING

PORTABLE POWER SUPPLY

Frequently Asked Questions

Can I use a different battery chemistry instead of a 3.7V Li-ion battery pack?

No, the BQ24074 charger IC is specifically configured and optimized for the charging profile and voltage thresholds of a 3.7V lithium-ion battery.

What tools do I need to assemble this power supply if no software is listed?

You will need standard electronics assembly tools such as a soldering iron, solder, wire strippers, and a digital multimeter for testing output voltages.

Why are multiple output voltages like 9.2V, 5V, and 3.3V available from a single 3.7V battery?

The circuit uses onboard voltage regulators and conversion stages to step up or step down the battery's base voltage to meet the specific requirements of various connected modules.

Gallery

This page is part of Kitkraft's Project Hub — a curated collection of electronics & robotics projects gathered from the maker community to help students and hobbyists discover and learn to build. Kitkraft does not claim authorship of the original project, and makes no representation as to the accuracy, completeness or safety of third-party source material. The summary and "How It Works" explanation above are AI-generated, rewritten with reference to the original tutorial — not a reproduction of it. Full credit and a direct link to the original source are provided above. If you're the original creator and have a concern about how your work is represented here, please contact us and we'll address it promptly.

Kitkraft Project Hub — curated from the maker community, credited at the source.

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