18650 Lithium-Ion Battery Pack

18650 is a lithium-ion battery which is also called 18650 cells having a voltage of 3.7 volts and a range of 1800mAh to 3500mAh. These batteries are available in protected and unprotected version but the protected version is recommended. The charge time it takes is 4 hours approx. which can be changed by the voltage of the battery and charger.

The name 18650 is depicting its size which is 18mm X 65mm. However, you can find out some minor changes.

What is 18650 Lithium-Ion Battery Pack Standard?

18650 li-ion battery has a standard pack available for replaceable and rechargeable batteries. It comprises the group of cells with a collective nominal voltage and capacity to work better for bigger devices used for both industrial and commercial markets.

What is 18650 Lithium-Ion Battery Used For?

18650 batteries are used in electronics, flashlights, remote cars, vaping and more. Other materials include laptops and electronic devices that need to be recharged. High lumen flashlights also use 18650 batteries.

Of you are good at it, you can change these batteries manually from the device but if not take extra care because the incorrect use or use of the wrong type of this battery can cause a fire.

How do you make 18650 Lithium-Ion Battery pack?

You can make this battery by yourself but be careful if you are unaware of the mishaps or you cannot tackle them then don’t even try it.

The things you need to make 18650 Li-ion battery pack:

1. Battery Level Indicator ( Banggood )

2. Rocker Switch ( Aliexpress / Banggood )

3. DC Jack ( Banggood /Aliexpress )

4. 18650 Battery Holder ( Banggood )

5. 3M x 10mm Screws (Banggood / Aliexpress )

6. Ni Strips ( Banggood / Amazon )

7. 18650 Battery ( GearBest / Amazon )

8. BMS ( Banggood / Amazon)

The tools you need to make 18650 Li-ion battery pack:

1. Spot Welder ( Banggood /Amazon)

2. 3D Printer ( GearBest )

2. Wire Stripper/ Cutter ( Amazon )

3. Hot Air Blower ( GearBest )

4. Multimeter ( Amazon )

5. Li-Ion Charger ( GearBest )

Safety Equipment:

1. Safety Goggles ( Amazon )

2. Electrical Gloves ( Amazon)

There are some steps to follow in order to make a standard li-ion battery pack. Let’s have a look.

Right selection for the 18650 cells for the battery pack

There are a lot of types of 18650 cells available in the market with a price range of $1 to $10. Make sure to select the right bunch of cells to make your battery pack. To make a standard battery pack use standard cells too as they have well documented and a good quality control mechanism. Buy the cells from known and trustworthy brands so that your battery will work for a long period of time. The brand 18650 itself is the best but have higher costs as well, make a better choice according to your affordability.

Make sure not to buy the cells having fire in the name as they are factory rejected cells and purchased by small companies to repack and sell.

Right selection of battery strips

To connect all cells together to make a battery pack you will need nickel strips or thick wires. In general, nickel strips are used widely to make which are available in the market with having two types.

Nickel-plated steel strips and Pure Nickel strips

It is obvious that Nickel strips are costly but these are a better choice as these generate less heat while charging and discharging the battery which eventually increases the battery life.

Spot welding

We can do soldering too but spot welding is a much secure way to connect the cells together with generating much heat. Hobby-grade and Professional grade are the two grades available in the market for spot welders. Professional grade cost ten times more than a good hobby grade so buying a hobby-grade is a good choice. You can easily buy them online from big online stores.

Check the Voltage

The cell voltage should be almost the same. Just check them ones before connecting them together. Else high voltage cells pass the current in low voltage cells which results in damaging the cells and battery and in worst scenario battery get fire.

New batteries of having a voltage between 3.5 V to 3.7 V are good choice but if you are using old laptop batteries you must check the voltage first.

Nominal voltage and battery capacity

You have to first figure out what should be a nominal voltage and the capacity of a battery pack. Then you are going to connect the cells in a way that will meet the required capacity and nominal voltage.

Assembling of cells

Arrange the cells in parallel to make a nominal voltage and then group them according to the capacity you need.

A first parallel group of cells are placed with the positive side up then second group with the negative side up and then continue this arrangement until you finish the group of cells. This assembling can be done with a plastic holder available for 18650 batteries.

Spot weld the Nickel strips

Put your strips over the group of cells and make sure that it covers all the terminals of each cell then leave extra 10mm strip to connect it to BMS. Cut it.

Now cut all the other strips for the remaining series of cells.

Now connect each group’s negative terminals to the other group’s positive terminal and so on.

Wear safety goggles and start welding the strips. First, make sure to adjust the welder according to the thickness of the strip you are using.

Connecting the battery to BMS

Connect the battery management system (BMS) with the soldering pads given in it i.e. B-, B1, B2, and B+. Connect the first negative terminal of the parallel group of cells to B- then second positive terminal to B1, similarly, third parallel group’s negative terminal to B2 and fourth positive terminal to B+.

Enclose the battery, connect the wires and assemble

The battery is having a cover of nickel plating so to avoid any shorting use some enclosing like PLA filament for a size you need. You can have one by using 3D printing or you can order one.

After enclosing, now connect the DC jack, rocker switch and to check the battery status, connect a battery level indicator with the battery by the wires.

After connecting now assemble the components in the PLA filament.

The positive wire available in the rocker switch and DC jack must be connected to the positive end of BMS and the negative wire goes to the negative end of BMS. Now cover the lid of the enclosing box and use the battery pack.