Diy Lithium Batteries: How To Successfully Build Battery Packs

Diy Lithium Batteries: How To Build Your Own Battery Packs

In the world of batteries, lithium-ion is king and used for so many applications like powering laptops, electric vehicles, and power packs.

If you’ve ever had to buy a new lithium battery you know they’re costlier than most, and when the batteries no longer work in your favorite device it’s pretty useless until you do.

If you’re someone who’s handy with tools and likes to set themselves a challenge, DIY lithium batteries could be the next project for you.

Learning how to make these batteries yourself is a lengthy ordeal that requires a few key supplies, but is a great project that can teach you how they work, and an exciting way to get your kids involved too.

If you are into homemade projects, check out our latest post about how to make activated charcoal.

How do you make DIY lithium batteries?

To make a 18650 lithium-ion battery you’ll need some items like a 18650 battery and Ni strips, as well as other tools like a hot air blower and spot welder. If you’d rather not take the total DIY approach, some battery building kits can give you the basics you need to create your own.

We’ll show you the basic steps needed to make your own lithium-ion battery and what you can do with this special type of power supply.

Even if you’re not interested in taking on the project, it’s a cool way to learn how this type of battery functions and exactly what goes into being one of the most popular sources of rechargeable energy we use today.

How Are DIY Lithium Batteries Made?

To understand how a lithium battery is made, it’s best to look at the different parts involved to see what their role is. If you were to open up and look inside a lithium battery, you’d find:

  • Cells: Lithium-ion cells can be either prismatic or cylindrical.
  • Temperature sensors: These keep an eye on the battery temperature to make sure it’s not overheating.
  • Voltage converter and regulator circuit: This manages the levels of current and voltage to keep them at a safe level.
  • Battery charge monitor: Regulates the charging of the batteries to make sure it’s happening quickly and efficiently.
  • Notebook connecter: A protected part that allows energy to flow in and out of the battery pack.
  • Voltage tap: This regulates the energy capacity of each cell inside the battery pack.

The Tools Needed for DIY Lithium Batteries

The Tools Needed for a DIY Lithium Battery

If you’d rather create a lithium battery pack from scratch without relying on a ready-made kit, there’s quite a lot of gear to assemble. In addition to these tools and materials, you should always be protected by electrical gloves and safety goggles whenever you’re working on this project.

The most important is choosing the right cells as there are many types of 18650 cells on the market and their price ranges between $1 to $15, but it’s better to opt for the more expensive brands.

Cheaper cells have a higher risk of exploding, their capacity is lower, and they are often factory rejects that have been relabelled and sold as new, when they’re anything but. Cells with a capacity of 3400 mAh are ideal.

You’ll also need:

  • 18650 battery and battery holder
  • Ni strips
  • BMS (battery management system)
  • Battery level indicator
  • DC Jack
  • 3M x 10mm screws
  • Rocker switch
  • Battery enclosure
  • Multimeter
  • Hot air blower
  • Hot glue gun
  • Wire cutter
  • Spot welder
  • Lithium ion charger

How to Make DIY Lithium Batteries

For the purpose of this project, we’ve used brand new battery cells that can be purchased as new. However, there are ways to recycle old batteries, like those from a laptop, but it requires a different approach.

Step 1: Test the Cell Voltages

Before we can connect the cells together, we need to establish their voltages. As we’re going to be connecting parallel cells, we want the voltage to be relatively similar, otherwise, it can damage them and lead to serious consequences like fire and explosion.

Generally, with brand new cells this won’t be a problem as they’re usually between 3.5V and 3.7V but using an old battery makes it less certain. If they’re not even, you can use your battery charger to get them to the same level before you start assembling and connecting them.

Step 2: Assemble the Cells

The battery pack has 15 cells in total, arranged into three separate parallel groups that have five cells in each. We now need to assemble them so they’re fastened together and our battery packs are solid enough to withstand use.

To arrange the cells correctly, turn the first group of cells positive side up, second group positive side down, and third group positive side up. Fasten them using your hot glue gun and give them time to dry.

Step 3: Welding the Nickel Strips

Welding nickel strips correctly requires a lot of planning as they have to be cut first and then checked for strength when you’re done. Place the nickel strip on top of the 5 cells and cut it so that it covers the cells with and has a 10mm excess on the end.

Use the strips to connect the first parallel group negative to the second group, and the negative second group to the positive of the third. With your spot welder, connect the strips together, and give it a pull to make sure it’s stuck tight.

Step 4: Connect the BMS

A battery management system has the important role of monitoring the groups of cells, preventing them from overuse, and making sure they all dispense voltage equally. These can be purchased for around $20 for a basic but brand new device.

The battery management system should have four soldering pads to use: B-, B1, B2, and B+, and they’re connected by the group. Look for the first parallel group and solder the negative terminal bus to the B- and the positive to the B1.

Then, find the third parallel group and do the same, with the negative terminal bus connecting to the B2 and the positive to the B+. Finally, solder the nickel strips to the BMS.

Step 5: Final Assembly

Attach the red wire of the DC jack and rocker to the P+ wire of the BMS and the negative wire from the DC jack and battery indicator to the P- wire of the BMS. Use your spot welder to solder them together.

Secure the battery pack using your hot glue gun so it’s closed securely, and then tighten the top lid screws with your 3M x 10mm screws.

Step 6: Testing

You can now test your lithium battery and with your charger, bring it back to full power as needed. You’ll be able to use your new batteries with a solar generator, small power bank, and anything else that takes 18650 lithium-ion batteries.

Making Your DIY Lithium Batteries Last

If you’ve put in a lot of effort making your own lithium-ion battery or purchased one brand new, you’ll want to ensure it lasts as long as possible.

There are a few things you can do to prolong the life of these batteries and keep them in good condition so that they don’t end up discharging quickly, burning out, or not being able to charge to full capacity again.

  • Don’t let the battery run all the way down to zero before charging it. Lithium-ion batteries don’t have a memory like other types, so a partial discharge won’t harm it. If you let the voltage of a lithium-ion battery run too low, you’ll ruin it forever.
  • A good lithium-ion battery will last around three years, and this is regardless of how often they’re used. It should be employed regularly to keep it in good condition because trying to “save” it will have the opposite effect.
  • Always store your batteries somewhere dark and cool, without being too cold. Heat can degrade a battery quickly, especially lithium-ion, so never leave them in direct sunlight or extreme temperatures.

Benefits of Using a Lithium Battery

Lithium-ion batteries are one of the biggest developments to happen in the world of portable power in years. These amazing batteries operate completely different from most sources of power, and have a range of benefits that others don’t.

  • Variety of sizes: A lithium battery can be small enough to charge an iPhone or large enough to store a power supply for a house. They’re able to be just about any size or shape you need, which means if you need battery power for something, you’ll find one to suit it exactly.
  • Low self-discharge: When a lithium battery isn’t in use, it has a very low rate of self-discharge. This is in stark contrast to other batteries that tend to discharge and lose power even if nobody is using them.
  • High energy density: The reason lithium-ion batteries are used for household electronics so frequently is that they don’t need to be charged as often. The whole time it’s running, it has a high current output, and it won’t fade out slowly with depreciating power, helping you stay on your phone all day without needing a charger.
  • Low maintenance: Larger scale lithium-ion batteries require very little in the way of maintenance, especially compared to other rechargeable types like nickel cadmium. They’re an affordable option in the short term and over the years when it comes to their maintenance.

The Devices a Lithium Battery Can Power

The main reason for the popularity of lithium batteries in recent years is because of the sheer volume of things they can power up. From the very smallest smartphone battery to something large enough to run an electric truck, a lithium-ion battery will usually be the thing doing all the heavy lifting.

A lithium battery is capable of being recharged which makes it very valuable, and they’re one of the most efficient power sources around. These are just a few ways you can make use of these batteries, but not always with the homemade variety:

  • Laptops and smartphones
  • Rechargeable electronics (handheld vacuums, video cameras, etc.)
  • Back up systems
  • Energy storage grids and systems

Related Questions

Lithium-ion batteries have revolutionized the way we look at rechargeable power, and although they have some faults, they’ve been a lifesaver for many applicants and devices.

We’ve answered some commonly asked questions about these special types of batteries that can give you some insight into why they’re so unique.


Some devices that use lithium-ion batteries have been known to explode or catch fire, and this is usually due to an internal short in the battery. This is usually because the separator sheet that keeps the positive and negative electrodes separate becomes damage, and allows them to touch. The result is a battery that overheats quickly and can explode or catch on fire within seconds.


The charge time for a lithium-ion battery depends on a few things, including the size of the battery and its build. Newer lithium batteries can receive a full charge in an hour or less, but the standard wait time is between two to three hours for it to reach 100%. Once the battery is full, it should be removed from the charger immediately and never left to sit there.


A battery or battery pack is not harmful when it’s in good condition and still enclosed in the metal and plastic casing that it was first manufactured in. However, if the battery overheats, it can release dangerous gases that can be harmful to inhale and cause irritation to the skin. When building batteries or working with them, you should always wear safety goggles and electrical gloves.

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