What is 18650 Battery?
An 18650 battery is just another variant of the standard lithium ion battery where these batteries have the ability to be recharged; basically a rechargeable lithium ion battery is known as 18650 batteries. These are also known as ‘flashlight batteries’. The 18650 just refer to the battery sizes just as AA does, but the only difference is that AA batteries may be made up of pure zinc, zinc-carbon, nickel-metal hydride, nickel cadmium or alkaline. But the 18650 are only lithium ion batteries and do not constitute of other metals.
The name 18650 refers to its size, meaning the first four digit clearly represent its dimensions where these lithium ion batteries are 18mm wide x 65mm long size. The AA batteries mainly come in sizes 14mm x 50mm, and those also can be called 14500 batteries. The fifth digit in the 18650 battery refers to its property of being cylindrical and indicates that it’s a cylinder cell. All the lithium ion batteries follow the same naming convention. Other lithium ion battery common sizes are 14500, 17670,181040 and 16340 The 18650 battery pack is the most common in everyday gadgets such as rechargeable laptop batteries, flashlights, and rechargeable hair straighteners and basically anything where this type of battery can fit in.
By default these do not come with a button or internal protection circuit but these can be modified but adding these both things. With the addition of button on top and internal circuit protection, the physical strength and capacity of the battery can be increased up to 65mm to 70mm in most cases, and even longer.
How is 18650 Battery made?
These batteries are different than usual batteries because their built in electrolyte is stable upto a range of 300 degrees Celsius. The way a 18650 can be made is by first making cathode and anode also known as, making a slurry where the materials are mixed altogether.
Then this slurry is coated by a current collector and etc that enable it for transporting electrons throughout which then is led by drying the solvents. The next step is calendaring where the materials are equally pushed and pressed together to form into a uniform mold. These materials are converted into sheets to be cut. Lastly, these sheets are rolled out and hermitically sealed in a steel case. The cells are then tested for various temperatures discharges and charges.
Properties of 18650 batteries
- Power and strength: The 18650 battery usually give an average of 3.7volts (sometimes can be in the range of 3.6 to 3.7), of current with the range of capacity from 1800 mAh going up to 3500 mAh. But most of these can full discharge at up to 2.5volts and completely charged at 4.2 volts. Just as an extra information for layman out there, the mAh refers to the unit time measurement of how much power is to be put out using that battery. Higher mAh means the battery has longer longevity, meaning it can last longer. The volts are the number which determine how much ‘push’ the battery will be giving to the power out there. Thus, the more number of volts refer to significantly large amount of current the battery can provide to power up every day electronic gadgets. You get more power for a longer period of time that you can reuse over and over again when you combine a higher voltage with higher mAh in a rechargeable battery.
- Load capabilities: These have a much higher density and way too higher load capabilities which significantly leads to them providing much higher voltage and a huge amount of current in a much smaller factor. Because they have lower self-discharge, they can last on shelves much slower than the usual AA battery cells or C cells commonly sold in the market.
- Charging rate: They can be charged fairly quickly as compared to other charging because of the charging algorithms they follow.
- Environmental safety: All 18650 come along with a protection unit, whether they are bought as an individual stand-alone unit or come in a battery back. They all have a built in protection circuit or a button top much like a AA battery which mathematically turns them into 19670 battery. If not, they would require a battery management system or BMS, which is a system that monitors the voltage been sent out by the battery while it charges and discharges. Both of these things can prevent a thermal runaway which will save the battery from exploding and create a much safer environment.
The best 18650 battery in the market?
An individual can select an 18650 that is above the minimum discharge of your unit, and then concentrate on charge power. For everyday use flashlights, the Panasonic NCR18650B is the go-to battery, and for high-drain electronic devices like cameras, the Samsung 25R.
Most 18650 batteries come with an embedded protection circuit boards (PCB) which make it enable for the battery to monitor the discharge rate and the overall internal and external temperature to further increase the longevity of the 18650 battery.
18650 Vs. 14500
The question arises when both these batteries are lithium ion batteries, how one can determine which battery to go for to put in as simple object as a flashlight. The clear cut go-to answer is 18650 if the cost and initial investment is not considered. But a person can not just all at once replace all his AA batteries with 18650 lithium ion batteries just because they’re better because of the fact that various gadgets work only better with the batteries their manufacturers suggest. Any electronic device which is designed for 18650 will only need 18650 and the one’s supporting AA won’t last long if 18650 is to be experimented with. Second of all, a good knowledge of batteries must be possessed with an individual at the time of buying batteries because there is no such thing in this world that does not have a counterfeit, so one has to be extreme careful before buying one.
The 18650 batteries are used in flashlights due to their high discharge rates and superior capacity. These come in various button top and flat styles and can go around 300-500 of charging cycles before it starts to die. However, this battery time can be increased if charged till 100% before discharging it.
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