How To Make A Rechargeable 12V Battery Pack From 18650 Battery

The breakthrough of rechargeable batteries in the market has been a revolutionary milestone that gave way to portable electronic devices. It also us the opportunity to use batteries and use alternative energy. This innovative technology allowed to harness the power of the sun and other natural sources and store them to a cell.

Today, rechargeable battery packs come in a plethora of models and widely used in various applications. Most of these devices use the lithium-ion battery technology because it is the more stable chemistry, basing the battery packs on 18650 power cell.

How to make a rechargeable 12V battery pack? As we all know, rechargeable battery packs can be expensive. That is why there are some people asking that question. However, with a piece of good knowledge and know-how on how rechargeable cells work, building a makeshift rechargeable pack is possible.

To create a rechargeable battery pack, it will require you a complete set of tools, materials, and use the right type of cells that will be the core of your makeshift device. And the most common cells used for a project like this is the 18650 lithium-ion cells.

To build the improvised device, you have to stack the cells on a battery holder, connect them with each other, and then to a circuit board called Battery Management System (BMS). After that, connect the necessary wirings that will be used for the part that will be receiving the current input.

That’s the basic build, but enclosing it to a durable plastic casing will be the final step that will secure everything in place. It may seem to be an easy task but is easier said than done, because it will require a lot of components, appropriate knowledge, and it will also take a lot of time. It is a process that needs a lot of focus and understanding of how each component works.

If you are planning to build your own makeshift rechargeable 12-volt battery pack, but you don’t have a concrete idea on what to do. I am glad to tell you that you are in the right place because I will be able to help you.

Several months ago, I was in the same position as you are now, and I was fortunate that one guy helped me build my first rechargeable power pack. To pass it forward, I made this guide to help people like you. So, let’s begin.

The Guide on How to Make a Rechargeable Battery Pack

If you want to build a makeshift rechargeable battery pack that you can use in various electronic devices like laptops, power tools, and medical devices. The first thing you have to understand that the core material that you need is the 18650 lithium-ion battery.

Apart from it, you also have to procure all other materials required for the project and a set of tools that will allow you to carry out every step in this guide.

Let’s start with the resources and tools you need.

Essential Components that You Need for the Project

In building a rechargeable power cell pack, the first thing you need to do is to procure the essential components for your project. These materials are going to be the parts that you will be assembling together to come up with the device.

So make sure that you get every single one of them and take notes.

● 18650 lithium-ion batteries
● Battery Management System or BMS
● Nickel strips
● Battery holder
● Battery charge level indicator
● Small electrical switch
● Direct current jack
● Screws

The Set of Tools that You Will Be Using for the Project

As mentioned earlier, before you can proceed to do this project, there will be a set of tools that you need to use. Without these tools, you won’t be able to carry out the vital steps in the whole process.

I also want to warn you that this project will require you to use a few advanced pieces of equipment and the knowledge to operate them.

Here’s a list of all the tools that you need.

● Spot welder
● Soldering iron
● Wirecutter
● Wire stripper
● Multimeter
● Hot air blower
● Screwdriver
● Lithium-ion charger
● Electrical gloves
● Safety goggles

The Complete Step by Step Procedure for the Project

Once you procured all of the essential materials that you need as parts of the device as well as the set of tools, you can now proceed to build the power bank. However, before you continue with the steps, you have to make sure that you have to prioritize your safety and wear the appropriate gear.

So, come and follow me as I walk you through each step.

If you like to watch a video than reading the how to guide, here is the video I found from YouTube below:

Step1: Picking the Right 18650 Power Cells for the Project

Before building your makeshift power bank, the first thing you have to do is to choose the right 18650 battery to use. You can’t just go out there and buy the first 18650 batteries that you see, that may lead you to get the batteries with poor quality and end up with an inferior device.

The best cells to use for your rechargeable battery pack are the ones from trusted brands like LG, Samsung, and Panasonic. You can get the green one manufactured by Panasonic because it has a 3400 mAh battery capacity.

Go ahead and get 15 to 20 pieces of this 18650 power cell.

Step2: Choose and Get the Right Nickel Strips for Connecting the Batteries

Once you got the right cells that you will use for the power bank, you now need to get the material you will use to connect them. For connecting the batteries with each other, you can either use thick wire or the more recommended nickel stips.

Nickel strips are the standard material used for a project like this, but be aware that there are two kinds of strips. One is the nickel-plated strip, and the other is the pure nickel. The strips made of pure nickel are the best ones to use because they have low resistance.

You also have to keep in mind that you have to get the strips that will suit the current rating your power bank will have.

Step3: Picking the Connecting Process You Will Do

Now that you have the power cells and the connector strips, you can are now ready to go to the actual process of building. In this part, you will need to choose how to carry on. It’s either you connect them using a soldering iron or spot welder.

Keep in mind that spot welding the batteries with the connector strips offer a better connection, but it is a bit expensive. Using a top-notch quality soldering iron is the cheaper option but will need more effort.

Step4: Check the Voltage of Each Power Cell

To get ready for the actual building process, you need to check the voltage of each of the 18650 battery using the multimeter.

Keep in mind that you are to connect the batteries in parallel, and checking the voltage of each cell will ensure that each cell will have a voltage within the same range. Otherwise, there will be too much current will flow to all of them and damage the cells with lower voltage.

Step5: Finalizing the Complete Plan for the Battery Pack You are to Build

Prior to the actual build, you have to finalize the specifications you intend for the device you are going to assemble. To do this, you have to determine the nominal voltage it will have and the capacity.

You have to remember that you are going to connect the batteries in parallel groupings, which will allow you to set the capacity for the device. And then, you will be joining the groups in series to enable you to reach your nominal voltage target.

Remember that you are using 18650 power cells with 3.7 volts and 3400 mAh specs if you are going for a device with a nominal voltage rated at 11.1 volts and 17 Ah capacity. You will have to connect 5 of the batteries in parallel to achieve the 17000 mAh device capacity.

To reach your 11.1 volts, you will have to create three parallel groupings and connect them in series.

Step6: Assembling the Battery Groupings to Prepare for Connecting

You are now ready to start the actual process of building the battery pack. Since you now established that you have to create three groups of five parallel connected batteries, then connect these three groups in series.

You can now start assembling the cells using the battery holder. This is to prepare them for making the connection between them and with the battery management system board.

Take five 18650 batteries and then place them into a holder with their positive side facing upward. For the second group, take another five cells and put them into a holder with their negative side facing upward.

Finally, take another five cells and do the same as the first group you made.

Step7: Cut Connector Strips and Connect the Batteries With Each Other

Start cutting the connector strips that you will use to make the connection within the battery grouping. Make sure to cut the strips in the length that will cover all of the battery terminals to ensure a secure connection.

Remember that you will only need four connector strips for the parallel groupings and then ten strips for the series connections. For the parallel strip connector, it is recommended that cut them a little bit longer since you will need it to be connected with the BMS board.

Spot weld or solder one strip to connect all the negative terminals of the first group, then do the same thing for its positive terminals. Then take the remaining two strips and do the same thing for the third group.

Now, take five smaller connector strips and connect each of the negative terminals of the first group with all the positive terminals of the second group. And then, take the other five to connect each negative terminal of the batteries in the second group with each of the positive terminals of the third group.

You have to make sure that you used the soldering iron or spot welder to connect the strips with batteries securely.

Step8: Making the Connection Between the Batteries and the BMS Board

After making sure that all the batteries are correctly connected, and the connection sequences are correct. You are now ready to add the battery management system board in the build.

The board is the electronic system that will manage the entire process of the battery pack you are building. So, you have to make sure to connect it with the batteries correctly.

There is four connection point within the board, and they are named as B1, B2, B- and B+. These are the points that have to connect the batteries with. To create the connection and incorporate the management system board, connect the strip on the negative terminals of the first group with the B- connection point of the board.

After that, connect the strip on the positive terminals of the first battery group with the B1 point. And then do the same with the third group of batteries. The negative terminals go to the B2 point and then the positive terminals to the B+ point of the board. To securely make the connection, solder, or spot weld the nickel strips with the points.

Step9: Preparing the Casing of the Battery Pack

If you have a 3D printer, it is an excellent option because it will allow you to create a customized enclosure for your power bank. However, you can have it printed for you from a 3D printing service.

You can also purchase an already built enclosure as long as it can fit the skeleton of the system that you assembled. You just have to keep in mind that your enclosure should have two parts, the main casing, and the lid. Having an enclosure will enable you to replace batteries after some time.

Step10: Setting Up the Wiring Components for the Device

Now that you are sure that your core components will fit the enclosure and you know the proper position of each element. You can now layout the wiring part, where it will be vital for the charging and discharging operations.

In this part, you can add various components like a battery indicator and switch for activating and deactivating the device. You also have the option to make it a more straightforward device and leave out those small components. However, cutting the switch and indicator off from the build will also get rid of the benefits they can offer.

To be able to be updated on the battery status, the indicator is convenient. The switch can be the one to be left out because it will just activate the indicator. However, it will use a small amount of current.

When it comes to the wiring, make a series connection for all of those small elements, then you can use a shrink tubing to make sure that all wires are secured, eliminating the risk of shorting.

You also keep in mind that the two ends of the wiring will be connected with the board’s P+ and then P- connection points. And to make the connection, you will have to solder them both, but wait until you have laid everything on the casing.

Step11: Completing the Build and Assembling the Device

You now have every component ready to be placed on the enclosure. The first step you have to take is to place the wiring that you made and carve slots on the enclosure where the level indicator, switch, and input/output jack will fit. Make sure that the three elements perfectly fit the slots and install them securely and firmly.

Once all of the elements are securely placed on the slots. Take the end of the positive wire that connects the jack with the switch and solder it the BMS board’s P+ point. After that, get the negative wire connecting the jack and level indicator, then solder it to be connected with the P- connection point of the board.

After that, clear out enough space within the enclosure for the battery pack you made and apply some hot glue where the batteries will sit in place. You have to make sure that the cells are securely seated on the enclosure and then place the lid of the enclosure, then seal the deal by using the screws.

Congratulations! You now built your first 12-volt rechargeable battery pack. The device you just made is ow ready to use, and you can charge it with a 12.6-volt DC adapter that you can easily buy from electronic stores. To use the unit for charging or powering your device, you will have to use its input and output jack.

Final Thoughts

Thanks for reading throughout my guide, and I hope you enjoy using the rechargeable battery pack you just built and find my guide helpful. With your makeshift rechargeable battery pack, you can now save some power that you can use as your backup power bank or use it for outdoor power.

Just make sure you keep away from using inferior batteries that can compromise your device build.