Electric Bike & Trike: 18650 3500 mAh Lithium Ion Battery Cells

By Addmotor | 07 December 2022 | 0 Comments
The rise in fuel prices and the drastic changes in weather conditions have convinced many people to think about their mode of transportation and carbon footprints. This realization has led many people to switch from their gas-powered vehicles to electric ones like electric bikes and electric trikes. Since then, electric bikes have been popular among young adults, while electric tricycle has been popular among adults who face difficulty maintaining stability on a two-wheel electric bike. Another component that makes a 2-wheel and 3-wheel electric bike distinct from traditional bikes is the built-in electric motor powered by a dedicated battery. This article mainly focuses on the type of battery cells used in an e-trike and e-bike, i.e., 18650 lithium-ion battery cells, how they work, and the top brands of 18650 lithium-ion battery cells.

How do electric trikes and electric bikes work?

Before we go into details about battery cells, let’s look at the specific purpose of battery cells in an e-trike and e-bike. The electric trikes and electric bikes have a built-in electric motor that works on a battery. This electric motor provides pedaling assistance to the riders, so they have to put minimal effort into pedaling, or when using full throttle mode where the rider is not pedaling at all, the electric motor does all the work to move the electric bike. As the electric motor is dependent on the battery, so the battery capacity of an e-trike or e-bike should be large enough to cover long distances. So many electric bike manufacturers prefer high capacity 3500 mah 18650 lithium-ion battery cells to build battery packs for their 2-wheel and 3-wheel electric bikes. 
GAROOTAN M-81 Electric Cargo Bike In White

What are 18650 3500 mAh Lithium Ion Battery Cells for electric bikes?

You may know that a battery consists of multiple individual cells, and there are two types of batteries commonly used, lithium-ion batteries and lead acid batteries. Lithium-ion batteries are preferred over lead acid batteries as they are more lightweight, safer, environmentally friendly, and have longer life expectancy than lead acid batteries. 3500 mah 18650 is a lithium-ion battery, in which 18650 indicates the dimensions of the battery. 18 refers to the diameter of the cylindrical cell, 65 refers to the height, and 0 refers to the cylindrical shape of the battery. The 3500 mAh in the name indicates the electric power output or battery capacity, which means the higher the power output, the longer the range of an electric bike and electric trike. You find these 18650 lithium-ion batteries in many electronic devices, such as smartphones, laptops, and flashlights, and are now being used in e-trikes and e-bikes.

► Raw material
There may be different raw materials or chemical compositions of 18650 lithium-ion batteries. So it is important to know about the chemical composition of the battery used in the electric bicycle and electric tricycle. The commonly used raw materials in the chemical composition of 18560 lithium-ion batteries include lithium iron phosphate (FePO4), Lithium nickel cobalt aluminum oxide (NCA), and Lithium nickel cobalt magnesium oxide (NCM). 

You might think that lithium-ion battery may be a recent invention, as it is being used in all of the latest electronic products, but the history of lithium-ion batteries goes back to the 1970s when it was first invented by Exxon researcher Michael Stanley Whittingham. Ever since the first invention, the research and modifications of lithium-ion batteries never stopped to make them more efficient and safe. In this race of developing a lithium-ion battery with high capacity and increased discharge, finally, in 1992 a group of scientists developed 18650 lithium-ion battery cells, which were sold by SONY in masses. Since then, 18650 lithium-ion battery cells are being used in many products, even in your everyday household products, you may find 18650 lithium-ion batteries in them.

► Lifespan

The lifespan of every 18650 lithium-ion battery cannot be the same because it depends upon several factors, such as the charging rate, surrounding temperature, depth of discharge, and the overall care of the battery. But an estimated lifespan of a typical 18650 lithium-ion battery is 300 to 500 charge cycles or two to three years. With proper usage and care, the lifespan of the 18650 lithium-ion battery used in an electric trike and electric bike may increase to four or five years.

► Pros and cons of 18650 3500 mah lithium-ion batteries

Though 18650 lithium-ion batteries are widely used in many products, there might be many advantages, but with that, there might be some disadvantages as well. So let's look at some pros and cons of 18650 lithium-ion batteries.
1. High energy density:
18650 lithium-ion battery cells have a high energy density, which means they can store and emit a large amount of energy to their size. This feature is very effective for electric bikes and electric trikes that require a large amount of power to cover long distances and also require a lightweight battery that doesn’t add upon their already increased weight.

2.High voltage cell:
The voltage of each 18650 lithium-ion battery cell is generally 3.6 volts, which is higher than that of other battery cells such as nickel cadmium, nickel metal hydride, which is 1.2 volts, and lead acid battery cells which produce 2 volts. This feature makes 18650 lithium-ion battery cells the best choice for
electric bicycles and electric tricycles, as they require a higher voltage to drive more power to the motor. 
3. No memory effect:
Another advantage of the 18650 lithium-ion battery is that it does not exhibit a memory effect which means you do not have to completely discharge the battery till empty before recharging it. This memory effect is commonly seen in other batteries, such as nickel-cadmium and nickel metal hydride when they are partially discharged before recharging. It reduces the charging capacity of the battery and overall lifespan.
4. Low self-discharge:
You might have noticed that batteries lose their charge even when they are not in use or supplying power. It is called the self-discharge rate of a battery. 18650 lithium-ion batteries have a minimal discharge rate compared to lead acid and nickel hydride batteries. The self-discharge rate of 18650 lithium-ion batteries is 1 to 2% per month. So the battery of your e-bike would discharge by only 1% if you don't ride it for a month.  

1. Requires battery protection:
18650 lithium-ion batteries can be easily discharged or overcharged. For this reason and to maintain the current in the safer range, they require some protection circuits for safe operation.

2. Costly:
18650 lithium-ion batteries are expensive especially when used for mass production of the items. They are 40% higher in cost as compared to nickel-cadmium. So this is the major drawback when the 18650 lithium-ion battery is used in e-trikes and e-bikes as it impacts their overall cost.

3. Aging:
The lifespan of 18650 lithium-ion batteries is 300 to 500 cycles, i.e., about 2 to 3 years. It is also a major disadvantage when 18650 lithium-ion batteries are used in
electric tricycles and electric bicycles as they would require battery replacement after every two to three years, which is not easy as the battery is embedded inside them.

The lifespan of 18650 lithium-ion batteries 

Charging speed of 18650 3500 mAh lithium-ion battery cells

On average, 18650 lithium-ion batteries take about 4 hours to charge but the charging speed of a battery depends upon several factors such as the brand of the battery, the type of charger used, and the capacity of the battery. So a 18650 lithium-ion battery with a higher capacity will take a longer time to charge compared to a battery with a lower capacity. Since we are talking about the 3500 mah battery capacity being used in an e-trike or e-bike, which is currently the highest battery capacity of a lithium-ion battery, it will take a longer time to charge. For instance, 1800 mah battery may take an estimated 1.5 to 2 hours to fully charge, while a 3500 mah battery capacity would take 3 to 4 hours.

Upkeep tips

To increase the lifespan of a battery or ensure proper and efficient functioning of the battery, efficient care, and upkeep tips are required.

• Before buying a charger for your e-bike or e-trike, keep in mind that the rapid charging rate increases the aging process of the battery. You may find chargers that may be 1 amp or higher and rapidly charge your e-bike, but this would decrease the longevity of the battery, so you may look for chargers that lower the charge current.

Batteries are highly subjected to temperatures, so keeping the battery of your electric bicycle and electric tricycle within optimum temperature is very important. Extremely high and low temperatures may affect the life of the battery. The optimum temperature ranges for storing 18650 lithium-ion battery cells are between 20 to 25 degrees.

Avoid overcharging the battery of your e-trike or e-bike as it would put additional stress on the cells, ultimately decreasing their lifespan. It is recommended to partially charge the battery as it will decrease the stress on the cells and increase their lifespan.

With overcharging, also avoid fully discharging the battery of an electric tricycle or electric bicycle. It would add more stress on the cells to recharge an empty battery rather than a partially discharged battery, thus increasing its aging process.  

Working principle of electric bike lithium ion battery

There’s a whole world inside a tiny battery that does all the work. So a 18650 lithium-ion battery contains a positive electrode made of lithium cobalt oxide, a negative graphite electrode, and a thin sheet of plastic separator between the two. As you charge the battery of your e-bike, the positive ions from lithium cobalt oxide leave the positive electrode, move across the separator towards the negatively charged graphite electrode, and remain there till the battery stores the energy. During discharging, i.e., when the battery supplies the power to your 2-wheel or 3-wheel electric bike, lithium ions move back to the positively charged electrode, thus powering the battery. During the movement of the ions across the battery, the electrons move around the outer circuit of the battery in the opposite direction.

How to build a DIY lithium-ion battery for your e-bike using 18650 cells

With the limited number of 18650 lithium-ion battery retailers available in the market and very few offering customizations, you can build your e-bike battery according to the size and the features you want. How can you do that? Let's look at it.
Things you need:
Before you begin, make sure you have everything required to build a 18650 lithium-ion battery for your electric trike or electric bike.
• 18650 battery cells
• Spot welding machine
• Nickel strips
• Digital voltmeter
• Hot glue gun
• Foam padding
• Battery management system (BMS)
• Soldering iron and solder
• Silicon wire
• Heat shrink tube
• Other connectors and wires
Now you have all the necessary things required to build a 18650 lithium-ion battery for your e-trike, let's look at the steps you need to follow to build a DIY battery.

Step 1: Determine the mounting location and shape of your battery

To build a battery for your electric trike, it is also important to determine where you would be mounting the battery in the 2-wheel or 3-wheel electric bike so that the battery is according to the size and shape of the space in which it would be mounted. According to the size and shape of the battery, the cells would be arranged in series and parallel, depending upon the number of cells that could fit in.

Step 2: Determine the arrangement of cells

Since we are talking about 18650 3600 mah lithium-ion battery cells, which are usually 3.6 volts. All these numbers will help you determine the arrangement of cells. To get the required voltage of your e-bike battery, the cells should be properly arranged in series. For a typical 36 volts battery, 10 lithium-ion cells are arranged in series. To get the maximum capacity of the battery you want, each cell with 3600 Ah capacity would be arranged in parallel. Drawing the shape of your battery and the arrangement of cells on a piece of paper would help you in assembling the battery. Represent the positive and negative ends of the cells with dark and light colors. Wiring would be such that the positive ends together and the negative ends together would be connected to form a parallel connection. While for series, the positive end of one cell would be connected to the negative end of the adjacent cell.   

Step 3: Test the voltage of the cells

It is important to test that all the cells have the same voltage that is required for your electric bicycle or electric tricycle and don’t have any defects. Testing it beforehand and replacing the defective cells would save you from any disappointments in the end.

Step 4: spot welding the cells

Now we are ready to connect the cells and pack them in a battery. Arrange the cells in the same way as you drew on the paper and cut the nickel strips to place them on cells connecting them in series or parallel. Some people use single or multiple pieces of nickel strips while connecting the cells. It's better to use multiple nickel strips to allow easy flow of current from each cell. While arranging the cells in shape, stick them together to hold them in place using hot glue and spot weld the nickel strips on the terminals of the cells.

Step 5: Attach and wire the BMS (battery management system)

So once you have connected all the cells and packed them into a battery, we’ll now add BMS to the battery back. A BMS monitors the battery cells and prevents the battery of your electric bike or electric trike from overcharging or over-discharging and keeps it in normal ranges. The BMS is secured on the battery pack by using a foam insulator underneath the BMS, and then BMS is attached to the battery pack with hot glue. Now we need to wire the BMS, i.e., add 10 little cell wires. Add each wire, soldering it on a nickel strip but not directly on the cell but between the two cells, which prevents the cells from heating up. Then finally, we add charge and discharge wires. First, the battery’s positive charge wire and discharge wires will be soldered to the positive terminal of the last parallel group of cells. Then, the negative charge wire will be soldered to pad C on the board and the negative discharge wire on pad P. Lastly, a wire would be connected from the negative terminal of the first parallel group of cells to pad B.       

Step 6: Seal your e-bike battery

Finally, the last step of your DIY e-bike or e-trike battery is to cover and protect it using a thin foam layer and a heat shrink. All these layers would protect the battery from external damage, in case the electric bike meets an accident. You can add a handle to easily remove the battery if you want.
That’s it! The 18650 lithium-ion battery is ready which you can now mount in your e-trike or e-bike and take a test ride.

Premium Brands of 18650 lithium-ion battery cells for electric bikes

Many brands in the market sell good quality 18650 lithium-ion battery cells. So it can be quite difficult to decide which brand you choose for the battery of your electric bicycle or electric tricycle. To help you in this, we have shortlisted some premium brands of 18650 lithium-ion battery cells for you to decide which one would be best for your electric trike or electric bike

1. Panasonic NCR18650B
You can never go wrong with Panasonic. Panasonic NCR18650B is one of the best 18650 lithium-ion batteries available in the market for electric bikes and electric trikes. It has two versions: flat top unprotected and button top protected.
The flat-top unprotected version has a 3400 mah capacity, 3.6 volts, and 6.7 A maximum discharge current.
Button top protected version has an internal protection circuit. It has 3360 mah capacity, 3.6 volts, and 6.7 A maximum discharge current.
• High capacity and energy density
• Low self-discharge
• High voltage
• Flat top unprotected can be risky to use as they can explode or burn.
• Low continuous discharge rate for e-bikes and e-trikes
2. Samsung 18650 INR series
The second premium brand for your 18650 lithium-ion e-bike battery is Samsung with its 18650 INR series. This Samsung series has two most popular 18650 batteries, commonly used in e-bikes and e-trikes.
Samsung INR18650-25R
The Samsung INR-25R battery cell is widely used in high-power battery packs for devices that need high-power output, such as two-wheel and 3-wheel electric bikes. It has 2500 mah capacity, 3.6-volt nominal voltage, and a maximum continuous discharge is 20 A.
• High continuous discharge is perfect for electric bicycles and electric tricycles as they require high power continuously, especially on terrains.
• High voltage
• High stability
• Moderately high capacity
• Unprotected
Samsung INR18650-30Q:
Another one from Samsung's INR series is Samsung INR18650-30Q which is a flat top high capacity battery of 3000 mah, 3.6 nominal voltage, and 15 A maximum continuous discharge.
• High Capacity
• Low internal resistance
• High voltage
• Unprotected
3. LG
LG is every household brand. It’s the most trusted and reliable name in cells and batteries. So what would be better than choosing LG 18650 lithium-ion battery for your electric bike? LG has also produced various 18650 battery cells.

LG HG2 18650 Li-ion Battery 
It is a high-capacity 3000 mah battery with a nominal voltage of 3.6 volts and 20 A maximum continuous discharge.
It is another popular model of lithium-ion battery from LG due to its high 3500 mah battery capacity, 3.65 nominal voltage, and 10 A max continuous discharge current.
• High Capacity
• High voltage
• High drain  
• Long life
• The capacity of LG HG2 reduces when discharging at a maximum continuous discharge rate.
• Both models have unprotected battery cells 

A buying guide for lithium-ion electric bike and electric trike battery cells 

Now you must know a lot about the battery cells for electric bikes and electric trikes. So here is an ultimate buying guide to choosing the right battery for your electric bike.
1. Voltage
Always look for high-voltage battery cells because that’s what drives the electrical energy to the motor of your e-bike and e-trike. So the higher the voltage of the battery cells, the more power the electric bicycle gets. Especially in the case of a 3-wheel electric bike, as it is heavier, it requires higher power.

2. Capacity
E-trikes and E-bikes require higher capacity battery cells to cover a long range. So battery cells with 3600 mah capacity are best for electric trikes.  
3. Size and weight
The battery pack shouldn’t be large that it gives an unpleasant look or is heavy, which makes the ride uncomfortable. The 3-wheel electric bikes that are already heavier in weight should have a battery that is small in size and light in weight.
4. Price
Investing in premium brands like Samsung, LG, and Panasonic and getting a high-quality battery for long-term use is never a bad idea.  
So this is all about 18650 lithium-ion battery cells for 2-wheel and 3-wheel electric bikes. We hope this information helps you choose the best lithium-ion battery cells for your electric bike.  


Leave a Reply

Your email address will not be published.Required fields are marked. *
Verification code
Latest Stories