Reuse Plastic Bottle to Make a Solar Bottle Lamp

Chapter 1: Solar Bottle Lamp Overview

  • Introduction to the solar bottle lamp

    • A sustainable project using reused plastic bottles

    • Useful for rural homes, gardening, and outdoor activities (camping, trekking)

Understanding the Solar Bottle Lamp Circuit

  • The circuit is divided into three main parts:

    1. Lithium-ion battery charger circuit

    2. Battery protection circuit

    3. Main circuit (LED driver circuit)

Lithium-Ion Battery Charger Circuit

  • Based on LP 4060, a linear battery charger IC

  • External components needed: resistor, capacitor, LED

  • LED indicates charging status (lights up when fully charged)

  • Capacitors C1 and C2 serve as filter capacitors

  • Resistor R5 sets charging current; R6 limits LED current

Battery Protection Circuit

  • Based on a Single Cell Lithium-ion Battery Protection IC (AP 6685)

  • Provides protection against:

    • Reverse polarity

    • Over-discharge

    • Over-charge

    • Short circuit

  • Needs only a resistor and capacitor

  • Derived from a typical application, not directly from data sheets

LED Driver Circuit

  • Based on transistors Q1 and Q2

  • During daytime, voltage from the solar panel turns Q2 on and Q1 off, enabling battery charging

  • At night, with no solar voltage, Q2 is off, and Q1 turns on, allowing current to flow from the battery to the LED

PCB Design and Assembly

  • Schematics drawn and PCB designed using Autodesk Fusion 360

  • PCB ordered for prototyping from PCBway

  • Quality of PCBs from PCBway is noted to be excellent

  • Assembling process:

    • Apply soldering paste on PCB manually with a syringe

    • Components placed as per schematics

    • Heating the PCB on a mini hot plate (MHP 30) for soldering

Chapter 2: The Solar Panel

  • Post soldering process includes:

    • Melting and reflowing solder paste on pads

    • Switching off the hot plate to prevent component damage

  • Installing the button switch on the PCB's bottom side

  • Options for pre-assembled PCBs available through PCBway, with relevant links provided

Enclosure Design and Printing

  • Enclosure designed using Autodesk Fusion 360

  • .stl files can be downloaded from Thingiverse

  • Printed using Reality CR 10 mini 3D printer

  • Instructions for the project are available on Instructables with links provided in the description

  • After printing, remove unwanted support structures and prepare for solar panel installation

Mounting the Solar Panel

  • A 5.5-volt solar panel used

  • Attached to the top of the enclosure using silicone glue

  • Ensure to remove the protective plastic cover from the solar panel.

Chapter 3: The Solar Lamp Assembly

  • Steps for assembly include:

    • Soldering terminal plates to the battery

    • Applying flux before soldering

    • Installing battery terminals in the enclosure

  • LED specifications:

    • 8mm straw hat LED used; longer leg is the positive terminal

    • LED mounted in its holder and sealed with silicone glue

    • Mount LED holder to the bottom of the enclosure

  • Installing additional components:

    • LED diffuser added

    • 3D-printed button placed in designated slot

    • PCB mounted inside the enclosure using screws

Final Assembly Steps

  • Solder terminal leads into the PCB

  • Install lithium-ion battery in the enclosure's two parts and secure them with M3 screws

  • Solar lamp tested using the button switch; brightness adjustable

  • Creation of three solar lamps in three different colors

Installation in the Plastic Bottle

  • Tool solar lamp for smooth placement in the bottle

  • Remove any plastic wrapping from the bottle

  • Fill the bottle with water (chlorine optional to prevent algae)

  • Close the bottle with the solar lamp replacing the original cap

  • Charge the battery before first use by placing in sunlight; lamp automatically turns on at night.