Lithium Batteries:18650 VS 26650

What is Lithium-ion battery (Li-ion)?

Lithium-ion batteries have the advantages of light weight, large capacity, and no memory effect, so they have been widely used. Many digital devices use lithium-ion batteries as power supplies, although their prices are relatively expensive. Lithium-ion batteries have a high energy density, their capacity is 1.5 to 2 times that of Nickel-Metal Hydride batteries of the same weight. At the same time, lithium ion batteries has a very low self-discharge rate. In addition, lithium-ion batteries have almost no “memory effect” and do not contain toxic substances, which are also important reasons for their wide application.

In addition, please note that the surface of the lithium battery is generally marked with English 4.2Vlithiumion battery (lithium battery) or 4.2Vlithiumion secondary battery (lithium secondary battery), 4.2Vlithiumion rechargeable battery (rechargeable lithium battery)

Quick Comparison

Comparison 18650 26650
Maximum charge voltage 4.2V 4.4V
Application mainly in flashlight mainly in High-drain devices
Capacity relatively low higher
Diameter 18MM 26MM
Charging time Average 4 hours Average 4 -6 hours

Table

1.What is 18650 lithium battery?

2.What does “18650” mean?


3.18650 Lithium Battery Overview


4.What are 18650 lithium battery used in?


5.Advantages of 18650 lithium battery


6.Disadvantages of 18650 lithium battery


7.What is 26650 lithium battery?


8.What are26650 lithium battery used in?


9.26650 lithium battery overview

10.Advantages of 26650 lithium battery

11.Disadvantages of 26650 lithium battery


12.The difference between 18650 and 26650 batteries


13.Which one is better? 26650 lithium battery or 18650 lithium battery?


14.How to choose right rechargeable lithium batteries for your devices?


15.Why 18650 batteries are famous?


16.Is it safe to charge batteries overnight?


17.Is it OK to use 18650 and 26650 together?


18.Can I replace 18650 battery to 26650 battery?

1.What is 18650 lithium battery?

18650 lithium battery is a standard lithium-ion battery model set by SONY of Japan. It is the originator of lithium-ion batteries, in order to save costs.

2. What does “18650” mean?

18650 is used to describe the dimensions of cylindrical lithium battery.Here is the basic naming rule of cylindrical. Among them, 18 means a diameter of 18mm, 65 means a length of 65mm, and 0 means a cylindrical battery. 18650 means that it has a diameter of 18 mm and a length of 65 mm. The model of the No. 5 battery is 14500, with a diameter of 14 mm and a length of 50 mm.

Generally, 18650 batteries are used more in industry and few in civilian use. The common ones are also used more in notebook batteries and high-end flashlights.

18650 Lithium Battery Overview

Common 18650 batteries are divided into Li-ion batteries and LiFePO4 batteries.

For 18650 Lithium ion batteries

Nominal voltage :3.7v

Charging cut-off voltage: 4.2V.

For 18650 LiFePO4 batteries

Nominal voltage: 3.2V

Charging cut-off voltage: 3.6V


Capacity: usually 1200mAh-3350mAh


The common capacity: 2200mAh-2600mAh


Cycle life: 1000 cycles of charging

What are 18650 lithium battery used in?

18650 lithium battery is commonly used in high-end glare flashlights, portable power supplies, wireless data transmitters, electric heating, warm clothing, shoes, portable instrumentation, portable lighting equipment, portable printers, industrial instruments, medical instruments, etc.

Due to the large capacity per unit density, most of it is used for laptop batteries. In addition, because the stability of 18650 at work is very good, it is widely used in major electronic fields.

PS: Lithium battery standard 3.7V or 4.2V are the same. It’s just that the manufacturer’s label is different.

3.7V refers to the platform battery book (atypical battery book) discharged during battery use, while 4.2 volts refers to the voltage when the battery is fully charged.

Common rechargeable 18650 lithium batteries, the nominal voltage is 3.6V or 3.7v, while when it is fully charged, the voltage will be 4.2V. The mainstream capacity of 18650 batteries ranges from 1800mAh to 2600mAh (the capacity of 18650 power batteries is mostly 2200~2600mAh), and the mainstream capacity is as high as the standard 3500 or 4000mAh or more.

Advantages of 18650 lithium battery

  1. Large capacity

The capacity of 18650 lithium batteries is generally between 1200mah and 3600mah, while the general battery capacity is only about 800mah. If combined into a 18650 lithium battery pack, the capacity of 18650 pack can easily break through 5000mah.

  1. Long life

The 18650 lithium battery has a long service life. And the cycle life can reach more than 500 times during normal use, which is more than twice that of ordinary batteries.

  1. High safety performance

The 18650 lithium battery has high safety performance. For one hand, It do not explode and catch fire. On the other hand, it is non-toxic and non-polluting.

We can see its structure. There is a galvanized steel shell to endure inner pressure. Thus it will not explode.

Further more, 18650 lithium battery has passed RoHS( Restriction of Hazardous Substance) trademark certification.

As we mentioned above, the number of cycles is greater than 500 times. It has good high temperature resistance. Because and the power-up efficiency can reach 100% even under 65℃.

In order to prevent short-circuiting of the battery, the positive and negative electrodes of the 18650 lithium battery are separated. Therefore, the probability of it short-circuiting is extremely low.

In order to avoid overcharging and over-discharging the battery, a protective board is installed inside. This method also can extend the service life of the battery.

  1. High voltage

The voltage of 18650 lithium batteries is generally 3.6V, 3.8V and 4.2V, which is much higher than the 1.2V voltage of nickel-cadmium and nickel-metal hydride batteries.

  1. No memory effect

The 18650 lithium battery does not have to empty the remaining power before charging, which is easy to use.

  1. Small internal resistance

The internal resistance of polymer batteries is smaller than that of ordinary liquid batteries. The internal resistance of domestic polymer batteries can even be below 35mW, which greatly reduces the self-consumption of the battery and extends the standby time of the mobile phone.

This is completely in line with international standards. This kind of polymer lithium battery that supports large discharge currents is an ideal choice for remote control models and has become the most promising alternative to nickel-metal hydride batteries.

  1. Wide range of use

18650 battery can be used for notebook computers, walkie-talkie, portable DVDs, instrumentation, audio equipment, model aircraft, toys, video cameras, digital cameras and other electronic equipment

  1. Flexible Design

It can be combined in series or in parallel into a 18650 lithium battery pack

Disadvantages of 18650 lithium battery

  1. Its volume has been fixed

The biggest disadvantage of the 18650 lithium battery is that its volume has been fixed, and it is not well positioned when installed in some notebooks or some products.

Of course, this disadvantage can also be said to be an advantage. This is a disadvantage compared to the customizable and changeable size of lithium batteries such as polymer lithium batteries. Compared with some products with specified battery specifications, it has become an advantage.

  1. There must be installed a protective circuit board inside the 18650 battery

The production of 18650 lithium batteries requires a protective circuit to prevent the battery from being overcharged and causing discharge.

Of course, this is necessary for lithium batteries, which is also a common disadvantage of lithium batteries, because the materials used in lithium batteries are basically lithium cobalt oxide materials, and lithium cobalt oxide materials lithium batteries cannot be discharged at high currents, and the safety is poor.

  1. Relatively Expensive

18650 lithium batteries have high production conditions. Compared with general battery production, 18650 lithium batteries have high production conditions, which undoubtedly increases production costs.

What is 26650 battery?

26650 lithium battery is a model specification of cylindrical lithium battery. The definition law of its model is: 26650 type, which refers to a battery with a diameter of 26mm and a length of 65mm. Common lithium batteries made of nickel-cobalt-manganese cathode materials and lithium iron phosphate materials: INR26650-3.6V-4500mAh, IFR26650-3.2 V-3200mAh.

What are 26650 lithium batteries used in?

26650 lithium battery is used in the fields of power tools, lighting, landscape energy storage, electric vehicles, toys, instrumentation, ups backup power supply, communication equipment, medical equipment and military lamps.

26650 lithium battery overview

Cycle performance: 2000 times(1C charge/1C discharge, capacity retention rate ≥80%, 100% DOD)

Maximum continuous discharge current: 9.6A

Pulse discharge current: 15A, 5s

Operating temperature: charging: 0°C~55°C; discharging: -20°C~60°C

Storage temperature: -20°C~45°C

Battery weight: 86 g (approximately)

For 18650 Ternary lithium-ion 26650 single cell

The nominal voltage: 3.6V

Nominal capacity: 4500mAh (capacity range 4500-4650mAh)

AC inner limit: ≤30mQ (plus PTC type)

Charging conditions: cut-off voltage 4.2±0.05V, cut-off current 0.01C. (Remarks: Charge at a constant current of 0.5C to 4.2V, and charge at a constant voltage until the current drops to 0.01C cut-off)

Discharge cut-off voltage: 2.75V

Cycle performance: 500 times (1C charge/1C discharge, capacity retention rate ≥70%, 100% DOD)

Maximum continuous discharge current: 13A

Pulse discharge current: 15A, 5s

Operating temperature: charging: 0°C~55°C; discharging: -20°C~60°C

Storage temperature: -20°C~45°C

Battery weight: 92 g (approximately)

Diameter: 26.2mm Height: 65.6mm

Advantages of 26650 lithium battery

1.Overcharge performance: After the battery is charged according to the standard, the initial state of the battery is measured.

When the battery state is normal, it is charged at a current of 3C to 10.0V, and then it is charged at a constant voltage to terminate at a cut-off current of 0.01C. Observe the appearance changes of the battery.

Result: No fire or explosion.

2.Over-discharge performance: After the battery is charged according to the standard, the initial state of the battery is measured.

When the battery state is normal, it is discharged at 0.5C to 0V. Observe the changes in the appearance of the battery.

Result; no fire, no explosion.

3.It is difficult to short circuit externally: After the battery is standard charged, the initial state of the battery is measured, and its positive and negative electrodes are directly shorted when the battery is dry and explosion-proof in the center (the total circuit current is not greater than 50mQ).

When the battery temperature drops to about 10℃ lower than the peak temperature, the test ends. Observe the temperature and appearance changes of the battery.

Result: No fire or explosion. .

Disadvantages of 26650 lithium battery

Because the 26650 lithium battery has a small range of use and its performance status has been replaced by the 18650 lithium battery, many manufacturers no longer produce this battery.

Both the 26650 lithium battery and the 18650 lithium battery belong to cylindrical lithium batteries. So, what is the difference between the 26650 lithium battery and the 18650 lithium battery? Let’s take a look at the difference between 26650 lithium batteries and 18650 lithium batteries.

18650 VS 26650    The difference between 18650 and 26650 batteries

1.Differentrated capacity:

the rated capacity of 26650 is 3000mAh,

the rated capacity of 18650 is 1100~1400mAh.

The battery capacity of 26650 under the same battery material is larger than that of 18650. Assuming that the same ternary material is used, the rated capacity of 26650 batteries is generally about 5200mAh, while the capacity of 18650 batteries is mostly about 2600mAh.

2.Differentdiameters of the two batteries:

the diameter of the 26650 is 26 mm

the diameter of the 18650 is 18 mm.

3.Different reference quality:

the quality of the 26650 production test is 94 grams

the quality of the 18650 production test is 45 grams.

4.Different battery volume;

the volume of 26650 is larger than that of 18650.

Their cell heights are the same and the cell diameters are different.

The diameter of the 26650 cell is 26mm, while the diameter of the 18650 cell is 18mm. 26650 battery is 8mm wider than 18650 battery.

V=πr2h

18650: d=18mm r=9mm Volume of 18650 =16532.1mm3

32650 : d=32mm r=16mm Volume of 32650 =52249.6mm3

5.Different battery capacity;

The battery capacity of 26650 under the same battery material is larger than that of 18650.

It is assumed that the 26650 battery with the same ternary material is generally about 5200mAh, while the capacity of 18650 battery is mostly about 2600mAh.

6.Different applications;

18650 lithium batteries are used in lighting batteries, industrial supporting lithium battery packs, power tool batteries, electric bicycle batteries, power lithium battery packs, etc.

While 26650 lithium batteries are used in integrated solar street lamp lithium battery packs, energy storage stations, solar energy storage batteries, etc. More.

7.Different battery life:

18650, which means it is 18MM straight and 65MM high. From this point of view, 26650 must be larger than 18650, so there is more space to fill the material and achieve a larger capacity.

At present, the capacity of 18650 is 2200, 2600, 3100 MAH, etc.,

WHILE the capacity of 26650 generally has 4000, 4200, 4500 MAH,

So the battery life will be longer.

Q&A :How to choose right rechargeable lithium batteries for your devices?

You just follow these steps:

Step 1: Read the instructions and guidelines on the electronic device.

This will provide you with the information related to voltage and compatibility and ensure you to buy the right one for your device.

Step 2:Eco-friendly batteries should be your first priority because they are great for your health and environment too.

Step 3: You need to consider its durability. Because you don’t want to purchase another battery before the year completes.

Step 4: If it is a protected battery. That means it is better to choose a rechargeable lithium battery with a PCB inside. Although PCB is a circuit, it is helpful to prevent battery from various problem like over-charging and over-discharging problems.

Q&A :Why 18650 batteries are famous?

Regardless their good performance, 18650 batteries are famous because they can carry more power and can serve today’s high-tech flashlights. In addition, nowadays, the SOP of factor manufacturing is highly mature. The battery inconsistency probably decrease, so the 18650 batteries are safer and more famous.

Q&A :Is it safe to charge batteries overnight?

No. In a way, charging batteries overnight is the behavior of overcharging.It can shorten lithium battery life and damage overall longevity of the battery. At the same time, overcharging will reduce battery capacity Although there is PCB(Protective Circuit Boards) inside batteries, it is suggested not to charge your batteries for a long time just like a whole night.

Q&A :Is it OK to use 18650 and 26650 together?

You’d better not do that. Although both 26650 and 18650 batteries can be used to provide power for all types of devices which require batteries, do not ignore lithium battery consistency because their sizes differs.

Q&A :Can I replace 18650 battery to 26650 battery?

No, you’d better not do that. Although 26650 and 18650 batteries are rechargeable regarding the current and output voltage, the size of 26650 is bigger than the size of 18650 battery. And every single cells are fixed in battery pack. It is difficult to change their position.