DIY 5V Rechargeable Power Pack For Cell Phones And Other 5V Devices

DIY 5V Rechargeable Power Pack For Cell Phones And Other 5V Devices

DIY 5V Rechargeable Power Pack For Cell Phones And Other 5V Devices

What You Will Need:

  • Used Laptop Batteries, Or Rechargeable Appliances That Include 18650 Li-Ion Cells
  • Various Pliers
  • Soldering Iron
  • 60/40 Solder
  • 18650 Battery Spacers
  • Charge/Discharge Cell Capacity Tester
  • Copper Bus Bar Ribbon
  • 5V Pcb Module Board With Overcharge, Undercharge, & Over Current Protection
  • 25Awg Wire
  • Kapton Tape
  • Battery Housing Case

(1) Salvage 18650 cells from old laptop batteries, rechargeable appliances, or anything that utilizes 18650 li-ion cells.

(Do not attempt to use anything other than li-ion cells)

(2) Reclaim the 18650 cells by carefully disassembling the battery case  that house the cells.

(Do not dent, scratch, or fracture the cells during disassembly)

(Do not attempt to use visually/physically damaged cells)

(3) Check the voltage of each individual cell with a multimeter set to read dc current

Preliminary Steps for choosing ideal cells

Connecting multiple 18650 cells together to create a larger battery requires preliminary steps to ensure the longevity and safety of each cell used. These steps will determine the statistics & performance of each cell. Knowing the specific voltage(V) and capacity(mah) of each cell is important to determine which cells are similar enough ideally work together. Grouping cells of similar voltage(V) and capacity(mah) for the project is ideal when considering performance and precision.

(Do not attempt to use cells that display a reading below 2.6V or above 4.2V)

(Only use cells that read a voltage between 2.6V & 4.2V)

(4) Check the capacity (mah) of each cell using a charge/discharge cell capacity tester

(Product suggestion: liitokala lii-500)

(5) Group cells of similar capacities together

(Do not attempt to group cells with a difference of 100-200mah in capacity.)

(6) Place grouped cells into battery spacers

(Make sure all cells are placed in the same direction)

(7) Solder cells in parallel with strips of flat copper bus bar ribbon.

(Do not attempt to solder cells in any other configuration other than “paralell”)

(Parallel wiring connects all the positive terminals together, and separately connects all the negative terminals together.)

(The end result is a pair of separate positive & negative terminal leads)

(8) Connect the battery to a 5v pcb module board

(Solder the positive & negative cell busbar leads to the corresponding positive & negative terminals of the 5v pcb module board.)

(Product suggestion: usb 5v, 2.1A pcb module board)

(Only use pcb modules rated for 5v, 2.1A that include overcharge, undercharge, & over current protection)

(9) Wrap cells in kapton tape to prevent damage, shorts, & electrical shock.

(Build or place battery in a rigid case to prevent damage to electronics)

(10) Re-charge with 5v usb wall charger or 5v usb solar panel.

Be Aware:

The amount of cells used & capacity may vary depending on the 18650 salvage yield. If all cells are wired in “paralell” properly; the nominal voltage of the power pack should be around 3.7V before the current is sent to the PCB module. The PCB module will step up the voltage to a steady 5V, 2.1A for safely charging 5V rated devices.

Aditional Electrical Theroy And Information

Utilizing The Abundant 18650 Cell

Utilizing the energy storage capabilities of 18650 Li-ion cell batteries conjoined with solar cells; creates opportunities to supply affordable, customizable, & portable; DIY solar storage units. Specifically the 18650 cell “battery” has an abundance of functional & economic uses for powering DIY electrical devices. 18650 Li-Ion cells are found in old battery packs, laptops, cameras and other high powered electronic devices. Utilizing these cells in a conjoined configuration will boost the total amount of energy stored to run any electrical device. The more cells joined together; the more energy & milliampere-hours(mah) a device will have to operate. Solar panels used in conjunction will recharge the battery port back up to full capacity.

“Reusing 18650 cells promotes a recycle friendly activity.”


Electrical Wiring Terminology

Series circuits: are sometimes referred to as current-coupled or daisy chain-coupled. The current in a series circuit goes through every component in the circuit. Therefore, all of the components in a series connection carry the same current. A series circuit has only one path in which its current can flow. Opening or breaking a series circuit at any point causes the entire circuit to “open” or stop operating.”

Parallel circuits: If two or more components are connected in parallel, they have the same difference of potential (voltage) across their ends. The potential differences across the components are the same in magnitude, and they also have identical polarities. The same voltage is applied to all circuit components connected in parallel. The total current is the sum of the currents through the individual components”


  • Connecting cells in “series” will increase your voltage output while the capacity(mah) will remain the same.

    “(Example): (3) 3.7V – 3200mah 18650 cells in series has an output of 11.1V @ 3200mah. – (3.7V)x(3)=11.7V & (3200mah)x(series ∞)=3200mah

  • Connecting cells in “paralell” will increase your the total capacity but voltage will remain the same.

    “(Example): (3) 3.7V – 3200mah 18650 cells in paralell has an output of 3.7V @ 9600mah. – (3.7V)x(parallel ∞)=3.7V & (3200mah)x(3)=9600mah

  • Connecting multiple groups of “series” cells in “paralell” will increase voltage and capacity at the same time.

    “(Example): 3 groups of (3) 3.7V – 3200mah 18650 cells in series & connected together in parallel has a total output of 11.1V @ 9600mah. – (3.7V)x(series 3)=11.1V & (3200mah)x(parallel 3)=9600mah

  • Cells in “series” operate like a chain; if one cell fails; the whole group will not work. However if you wire them in “parallel” each cell works as a team; if some fail; the whole array will still work but at less capacity(mah).
  • Wiring in “series/paralell” works by gathering multiple cell groups in “series” and connecting those groups in “paralell”. This allows everything to operate as separate groups in even if a group of cells in “series” fail. Wiring “series” grouped cells in “paralell” will allow current to flow past the failed group; to allow current to flow to the rest of the operating groups. In this case think of the grouped cells in “series” as an envelope and the whole connected groups in “paralell” as the container that holds all the grouped cells.

Watt(W): net unit of power

kwh: kilowatts per hour

mah: milliamps per hour

ah: amp hours

Volt(V): potential difference in energy



Ohms Law

V=I*R      I=V/R      R=V/I


“Average” Notable “18650” Voltage Reading Specs

4.2V @ Full Charge

3.7V @ Nominal Charge

(2.4V – 0V) @ N/A – 0 

Information Resources – “This Cell Database is a community-driven project to catalog pictures, datasheets, and other useful information for the various battery cells”

Disclaimer: DIY projects that involve electricity are extremely dangerous. The misuse and mishandling of electricity can cause harm, permanent damage, and death in some scenarios. A pre knowledge, awareness, professional knowledge/assistance, & safety protocols of basic electrical theory is strongly recommended before partaking in electrical projects. This video does not include details on electrical theory or explanations on how to use specific equipment and their recommended safety protocols to complete this project. Please follow at your own risk; consult a professional electrician; and educate yourself before conducting this or any electrical projects. This content and creator is not responsible for any harm/damage to anything or anyone in relation to this article and video. This project is not responsible for any outside influence or ideas formulated in relation to the technology displayed in this article and video. 

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