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. 

Like (0)

DIY Rewiring & Expanding Solar Panels For Charging 5v Devices Via USB



The ebay link below is a great recourse for purchasing quality hand made solar cells. This article is based on these specific solar cells, or solar cells of a similar design.

ebay – 5V Home Made Solar Panels – $19 for 5pc – Free Shipping

Each solar panel unit is 5V, 0.55A, 2.75W, (8.8″ x 3.4″ Inches) with a USB2.0 plug for power.

Each Solar Panel comes equipped with the ability to individually charge your cell phone or power bank; via USB. A single solar panel listed above is rated at [5V, 0.55A,] and will charge significantly slower than a standard USB [5V, 2A] wall outlet charger. However if you want to modify your solar panels to match total output of a standard USB wall outlet charger; you will need to expand the total capacity by wiring “4” solar panels together in parallel.

(See attached DIY_SOLAR_ EXPANDING_ASSEMBLY.pdf for visual instructions to the following article)

Tools And Supplies Needed:

assembly of the 4 solar panels requires: A Soldering Iron, 60/40 Rosin-Core Solder, Soldering Flux, Kapton Tape, 24awg Wire, & Solar Busbar Wire Ribbon.

Solar Wiring Specs:

Connecting solar panels in “parallel” will increase the total solar panel capacity or amperage(A) while maintaining the same voltage(V). Parallel wiring essentially connects a positive terminal from one panel to the positive terminal of the consecutive panel. The same rule applies for the negative terminals; negative terminals connect in succession to the neighboring negative terminal. Think of parallel wiring as; each solar panel working in a “team” of passing current to the next panel. If one panel in the unit “fails” the current will pass over the faulty panel to allow the others to still output power.

“(Example): (4) 5V , 0.55A solar panels wired in parallel have an output of 5V, 2.2A; a total of 11W of power; instead of 2.75W that only 1 panel provides.

5 x 1 = 5V (Voltage stays the same because parallel wiring creates a single solar unit rather than 4 individual solar panels.)

0.55 x 4 = 2.2A (Amperage increases because we are multiplying the amperage of a single panel by the amount of panels used in the group.

2.2A x 5V = 11W (Total power)

Connecting the leads properly in “parallel” is crucial to an intentionally functioning solar panel unit. Be aware to not wire your panels in “series” for this specific application. Accidentally wiring in series would result in multiplying the voltage and will overload the device you are charging. Wiring in “series” would require the positive terminals to connect to the negative terminals of the neighboring panel. However for this specific application; it is crucial that series wiring does not happen.

Basic Soldering Knowledge:

Before you start the wiring process; it is important to have some basic knowledge on soldering. Be aware that soldering irons can be dangerous and harmful if not handled properly. Never hesitate to research for assistance if you are not comfortable using a soldering iron.

> Pick a well ventilated and dry workstation with no flammable debris. Soldering irons can reach temperatures of +800°F and can easily burn or cause fires if not handled carefully.

> Smoke from soldering can be harmful if inhaled. Please use proper ventilation, eyewear, and face-mask when soldering.

> When using a new soldering iron or installing a new soldering tip; It is important to “pre tin” your soldering tip before its first use. In high temperatures: soldering tips are easily oxidized when exposed directly to the air. Immediately applying soldering flux and solder to a new heated tip will adhere and cover the soldering tip to prevent oxidation and long-term damage.

> Pre tinning the soldering iron tip is a necessary routine for every time the soldering iron is in use. Pre tinning the soldering iron will also allow the direct soldering process and solder to adhere to whatever you are soldering.

For further tips on soldering; please visit this youtube Link. This video and YouTube Channel are great resources for electronics assembly knowledge. One of the top soldering iron manufacturers: “Weller” has detailed read along resources available on proper soldering procedures: Weller Recources

See; DIY_SOLAR_ EXPANDING_ASSEMBLY.pdf for visual examples to the following steps.


Take 4 solar panels and desolder the leads directly connected to the USB port using a soldering iron. Only the usb ports should be removed. When desoldering the USB port terminals; use a quick amount of applied heat from the soldering iron tip to the terminal joints. This will quickly liquify and disconnect the previously made solder joint. Solder has a quick melting threshold and should liquify the previous connection very quickly. Be sure to apply direct heat from the soldering tip. Be aware: unnecessary and long term applied heat may damage electronics. Once detached; set aside and save the usb ports. One of these USB ports will be re-soldered and used to complete the project. Be sure to keep note of which terminals on the USB are positive and negative. This is crucial information to know when re-soldering the USB back on. Be aware: wires directly connected to the solar panels should not be desoldered. “ONLY DESOLDER THE USB CONNECTIONS”.


Flip the 4 solar panels so that the glass is facing down and the back of the panels are facing up to view the back wire leads. Place the panels in an orderly row; touching side to side so that all negative and positive leads are on the same side as each other. Example; all positive leads should be on top, and all negative leads should be on the bottom. (The red wire is the positive lead, and the black wire is the negative lead). With kapton tape; adhere the panel edges so that all 4 panels are held together with tape.


Now that all panels are side by side; cut off two strips of solar busbar ribbon; about 3/4 the length of the 4 solar panels. The length of the busbar ribbon does not need to be an exact measurement. The solar busbar wire ribbon will act as an electrical bridge that unifies all the negative leads together; as well as separately all the positive leads.


Take the negative lead end of the first solar panel, and the end of a cut solar busbar ribbon, and place them on top of each other. Prep the two areas by applying flux to the busbar and the negative bare wire to ensure a good adhesion when soldering. Flux prevents oxidation and allows copper to adhere by flowing a filler metal in between the connection. With a hot and pre tinned soldering iron; touch the soldering iron tip to the negative lead that is stacked on top of the busbar ribbon end. The heated area will quickly flow with metal and form a smooth connection. This will adhere the negative lead to the end of the busbar strip.

By continuing to solder the positive ends to other positive ends is essentially what parallel wiring is. For all parallel wiring applications; do not cross solder the positive and negative leads together. The positive bus bar and wires connected should be unified and separate from the negative busbar and leads. Connecting the positive and negative leads and or busbars together can cause an accidental boost in voltage or an electrical short.

Continue to solder the rest of the negative leads to the same busbar wire using the same soldering techniques. The rest of the negative leads should be spread out evenly across the rest of the negative busbar wire. Be sure to leave at least 1cm of room at the end of the busbar . This same application method and busbar wiring should be a applied for the positive lead connections as well. At this point there should be two parallel busbars running across the back of the solar unit with all corresponding leads connecting to them.


Take a desired amount of 24awg wire and strip the silicone coating off of each end to expose the bare wire. Twist and tin the tips of each bare wire end. Solder new leads from the end of each busbar directly to the corresponding positive or negative terminal on the USB unit. The end result should essentially be a 4x version of the original solar panel with a [5V, 2.2A] output.

Like (0)