Building a 18650 Charge Circuit: A Beginner’s Guide

Are you a beginner in the world of electronics and searching for an exciting project to build? Look no further than a 18650 charge circuit! This small but mighty device is used to recharge lithium-ion batteries, making it an essential tool for any DIY enthusiast. With its compact size and simple design, building your own 18650 charge circuit can be a fun and rewarding experience. In this beginner’s guide, we’ll explore what exactly a 18650 charge circuit is, the different types available, their pros and cons, materials needed for building one yourself, step-by-step instructions on how to do so, as well as some alternatives if you’re not quite ready to take on this project. So let’s get started!

What is a 18650 Charge Circuit?

A 18650 charge circuit is a circuit that can charge a 18650 lithium-ion battery, which is a type of rechargeable battery with a nominal voltage of 3.7V and a typical capacity of 2000-3500mAh. A 18650 charge circuit usually consists of a power source, such as a USB port or a solar panel, a battery charger IC, such as TP4056 or MCP73831, and some passive components, such as resistors, capacitors, LEDs, and diodes. A 18650 charge circuit can also include a protection circuit to prevent overcharging, over-discharging, over-current, or short-circuit of the battery. A 18650 charge circuit can be designed using various methods and components, depending on the desired charging current, charging voltage, charging time, and safety features. Some examples of 18650 charge circuits are given below123:

A simple 18650 charge circuit using TP4056 IC and a micro USB port as the power source. This circuit can charge the battery with a constant current of 1A and a constant voltage of 4.2V. The LEDs indicate the charging status. The TP4056 IC has built-in protection features for overcharging, over-discharging, over-current, and short-circuit.

A solar-powered 18650 charge circuit using MCP73831 IC and a solar panel as the power source. This circuit can charge the battery with a constant current of 500mA and a constant voltage of 4.2V. The LED indicates the charging status. The MCP73831 IC has built-in protection features for overcharging, over-current, and short-circuit.

A boost converter 18650 charge circuit using FP6291 IC and a USB port as the power source. This circuit can charge the battery with a constant current of 1A and a constant voltage of 4.2V. The LEDs indicate the charging status. The FP6291 IC can boost the input voltage from 5V to 8V to provide enough power for charging. The FP6291 IC has built-in protection features for overcharging, over-current, and short-circuit.

These are some of the possible ways to build a 18650 charge circuit. You can also modify or combine these circuits to suit your specific needs and preferences.

The Different Types of 18650 Charge Circuits

When it comes to 18650 charge circuits, there are different types that you can choose from. Each type has its own advantages and disadvantages depending on your needs and preferences.

One common type of 18650 charge circuit is the linear charger. This circuit charges the battery by regulating the voltage using a transistor or regulator. It’s simple to use and relatively inexpensive but may not be as efficient compared to other types.

Another type is the switch-mode charger which uses high-frequency switching technology for more efficiency in charging. It’s also smaller in size than linear chargers making it ideal for portable devices with limited space.

A multi-stage charger is another option that monitors the battery voltage and adjusts charging levels accordingly. This helps prevent overcharging which can damage your batteries over time.

There are USB-based chargers that allow you to charge multiple batteries simultaneously through a computer or USB wall adapter port. These chargers are convenient for those who need to charge several batteries at once, but they may not be suitable for heavy-duty usage.

Choosing the right type of 18650 charge circuit depends on your specific requirements such as budget, size limitations, charging speed, and safety concerns.

Pros and Cons of a 18650 Charge Circuit

A 18650 charge circuit can be a great addition to your electronics projects, but like any other technology, it has its pros and cons.

One of the biggest advantages of using a 18650 charge circuit is that it allows you to recharge batteries without having to remove them from your device. This means you don’t have to worry about buying new batteries every time they run out of power – all you need is a way to recharge them!

Another pro of using this kind of circuit is that it’s relatively easy and affordable to build one yourself. You don’t have to be an expert in electronics or spend a lot of money on fancy equipment – with just a few basic tools and components, anyone can build their own 18650 charge circuit.

However, there are also some downsides to consider. One potential drawback is that these circuits can be quite sensitive and require careful setup; if something goes wrong during construction or use, you could end up damaging your batteries or even starting a fire.

Additionally, while building your own 18650 charge circuit can save you money in the long run by allowing you to reuse old batteries instead of constantly buying new ones, it does require an initial investment in materials and time.

Ultimately whether or not a 18650 charge circuit is right for you will depend on your specific needs and circumstances – but understanding both the pros and cons should help inform your decision-making process.

What Materials Do I Need to Build a 18650 Charge Circuit?

Building a 18650 charge circuit requires a few materials that are easy to find. Firstly, you will need an 18650 battery holder or cell holder. This is where your lithium-ion batteries will sit and connect to the circuit board.

Next, you’ll need capacitors for voltage stabilization, resistors for current regulation and diodes for reverse polarity protection. These components can be found at local electronics stores or online shops.

You’ll also require a printed circuit board (PCB) which is the backbone of your charge circuit. The PCB serves as a platform to mount all other components including the battery holder.

A microcontroller unit (MCU), such as Arduino, is required if you want to add smart charging features like overcharging protection, low voltage detection and automatic cutoff.

Soldering equipment such as a soldering iron and solder wire are essential tools in assembling the parts together on the PCB.

Before purchasing any materials make sure they match your requirements by checking their specifications with those listed in your design plans.

How to Build a 18650 Charge Circuit?

Building a 18650 charge circuit may seem like a daunting task, but with the right materials and steps, it can be done easily. Here’s how to build one:

Firstly, gather all the necessary materials including a 18650 lithium-ion battery holder, TP4056 charging module board, micro USB cable, and wires. Make sure you have access to a soldering iron as well.

Next step is to connect the TP4056 charging module board to the battery holder using wires. The positive end of the battery should be connected to B+ on the charger board while its negative end should be connected to B-.

Now it’s time for connecting USB port in which you need two more wires: one for VCC and another for GND. Connect them accordingly by following polarity diagrams given on both boards.

Once everything is connected properly double check your work before plugging in your micro USB cable into your power source.

Finally plug in your 18650 battery into its holder and watch as it charges up! It’s that simple!

Remember safety first when working with electronics so always wear gloves and goggles during this process.

Alternatives to Building a 18650 Charge Circuit

If building a 18650 charge circuit seems intimidating or too time-consuming, there are alternatives available. One option is to purchase a pre-built 18650 charger from an electronics store or online retailer. These chargers come in various sizes and price ranges, but be sure to check the reviews and specifications before making a purchase.

Another alternative is to use a power bank with built-in charging capability for 18650 batteries. This can be convenient for those who already have a power bank and want to avoid purchasing additional equipment. However, it’s important to make sure that the power bank has the correct output voltage and current for your specific battery needs.

Additionally, some devices such as flashlights and vaporizers may include their own built-in charging circuits for 18650 batteries. If you’re using these types of devices frequently, this could be a viable option.

Regardless of which alternative you choose, it’s important to prioritize safety when charging lithium-ion batteries like the ones found in 18650s. Always follow manufacturer recommendations and never leave batteries unattended while charging.


To sum it up, a 18650 charge circuit is an essential device for charging lithium-ion batteries. It’s important to choose the right type of circuit that suits your needs and budget. You can either go for a pre-built charge circuit or build one yourself.

Building your own 18650 charge circuit can be intimidating at first, but with the right materials and instructions, you can easily create one. However, if you’re not confident in your skills or don’t have enough time on hand, pre-built circuits are also widely available online.

At the end of the day, having an efficient and reliable 18650 charge circuit will greatly benefit you in terms of convenience and safety when handling lithium-ion batteries. Whether you decide to build one from scratch or purchase a pre-made option, always prioritize quality over cost to ensure optimal performance and longevity.