All 18650 size (form factor) batteries have their pros and cons. Therefore, it is difficult to talk about which 18650 batteries are better. It is rather a matter of personal preference and the requirements that you place on the battery. Battery specifications and features depend on the type of chemistry (electrolyte) used.
Protected and unprotected lithium-ion batteries
First, let's look at the difference between protected and unprotected 18650 batteries. Which of these two types is better will become clear after parsing these terms. Protected (Protected) batteries are batteries with a small board (charge controller) “sewn” into the case, which has the three most necessary functions: short circuit protection, deep discharge protection and exceeding the allowable current during charging. Along with protected ones, there are also unprotected ones.(Unprotected) batteries without internal board. These need to be handled with great care, especially when running them with very low resistance.
Depending on the chemical composition of an unprotected battery, it can either permanently deteriorate or simply explode. You can find out if the battery is protected by reading the small inscriptions on its case. Short circuit translated into English will be Short-circuit, protection - Protection. If you met these two words on the same line, then you can be sure that there is protection. Also, individual words Protection or Protected will say the same thing. Unfortunately, not all batteries write about the presence of a little savior in it. Alternatively, you can use the search for battery information from sellers or on the Internet. If you put safety at the forefront when choosing a battery, then the answer to the question of which 18650 battery is better becomes obvious.
Li-ion battery mechanical protection
In addition to the electronic internal protection of the battery, there is also a mechanical protection system without the use of a board. The meaning of such protection is reduced to a mechanical break in the circuit (activation of a mechanical switch) inside the battery as a result of exceeding a certain threshold of internal pressure, which, in fact, leads to an explosion. This de-energizes the battery. If the pressure still continues to grow, then a special valve automatically opens, which extracts the electrolyte out. The mechanical switch itself is quite widespread as an additional safety measure in many batteries, built in with or without a charge controller (board). At the same time, the presence of mechanical protection may not be mentioned anywhere at all, neither on the case, nor in the description of the technical characteristics in the store. In this case, you just need to understand that batteries with an unstable chemical composition will never be left unprotected by a good manufacturer. Even if officially such a power supply is considered unprotected, it will in any case have at least some mechanics.
Li-ion battery capacity
Battery capacity is expressed in milliamps per hour (mAh or mAh) and also helps you determine which 18650 battery is best suited for use with your device. The higher this value, the longer the battery will last until it is completely discharged. Milliamp per hour is a derivative of "amps per hour" (1 Ah=1000 mAh) used for small batteries. Without going into physics, this value characterizes the potential strength of the battery current, which it must give out for one hour in order to be completely discharged. Of course, it may not give out such a strong current, but by this value one can easily judge its capacity. With the help of simple calculations, you can find out what current the battery will produce for several hours of operation, based onequality - the number of amperes in one hour. The higher the ampere value, the longer the battery can work with the same power.
Current output of lithium-ion batteries
Current output is another parameter that characterizes a battery. On the battery case, the current output is marked by the current strength - ampere (A). The more amps, the stronger the battery will “fry”. Batteries with high amperes are considered high current (High drain). It is the number of amperes that determines which high-current 18650 battery is better. However, these batteries have a relatively small capacity. The lower the resistance with which the battery must work, the more current it will have to give. And the limit of this return depends on the described value.
The capacity of the battery determines the strength of the current over time, and the current output shows this limit. Based on these two parameters, you can calculate the maximum battery life with the maximum possible power for it. It is important to understand that if the current required for a particular device is greater than the maximum current output of the battery with which this device works, then this will be an overload for the battery. The working life of the battery with constant work in a heavy load is greatly reduced.
Ohm's Law as a method to find out which 18650 batteries are better in terms of technical characteristics
Knowing the nominal voltage of the power supply and the resistance of the device, you can calculate the required current output,using Ohm's law:
I=U/R, where I is current in amps (A), U is voltage in volts (V), R is resistance in ohms (Ohm).
That is, you need to divide the battery voltage by the resistance of the final device. Using the formula, you can protect the battery from a possible overload in operation, and certainly from a short circuit. Ohmmeters are used to measure resistance. Knowing how to do these simple calculations will help you determine which 18650 battery is best suited for use with a particular device.
All 18650 form factor batteries are rated at 3.7 volts. But this value in most cases is variable and depends on the level of battery discharge. The more it is discharged, the less volts it produces.
Types of lithium-ion batteries
Which 18650 battery to choose, and which one is better - depends on the specific situation. Knowledge of the features of various types of chemistry will help to understand this issue. Below are the most popular types of 18650 battery chemistry:
- Lithium Cob alt - ICR, NCR, LiCoO2 (Lithium Cob alt Oxide).
- Lithium manganese – IMR, INR, NMC, LiMnO2, LiMn2O4, LiNiMnCoO2 (Lithium Manganese Oxide).
- Lithium iron phosphate (ferrophosphate) - LFP, IFR, LiFePO4 (Lithium Iron Phosphate).
The listed types of batteries are varieties of lithium-ion batteries, that is, made using lithium-ion technology.
The following information with descriptions of the types of chemistry will help you determine which 18650 Li-ion battery is best.
Aging, storage and operating temperature range of lithium-ion batteries
All lithium-ion power supplies age. It doesn't matter if they are used at all. It is believed that after several years from the date of production, in any case, they can be safely thrown away. Each year, the battery loses approximately 10% of its nominal capacity, so it is recommended to find out the date of manufacture before buying. Along with aging, lithium batteries have another small disadvantage - they cannot be stored in a discharged state for a long time, this can ruin them. Batteries are also affected by ambient temperature. Lithium-ion cells have a relatively low operating temperature range - from -20 degrees to +20 degrees Celsius. This means that using or charging them in conditions close to the indicated limits will adversely affect the electrolyte.
Lithium cob alt batteries
Lithium cob alt batteries have the highest capacity. Lithium-cob alt chemistry is very unstable, so it must be used with care. The possibility of fast charging should not be allowed when using the boost or delta V charge method. With this charge, a more stable battery can be fully charged within one hour. Lithium-cob alt is dangerous to charge in this way. Also, do not use a lithium-cob alt battery with such a load thatit can be discharged in less than 30 minutes. For a battery with this chemistry without protection, both will ignite the electrolyte.
Chemistry based on lithium-cob alt technology has found great popularity among 18650 e-cigarette batteries. Which is the best manufacturer of batteries in this category to choose, it is recommended to look in the reviews. Due to a certain instability, such batteries must be chosen carefully.
The threshold value for the charge of a lithium-cob alt battery is the border of 4.2 volts. Jumping battery voltage above this limit will mean overcharging, which is highly discouraged. Using too powerful chargers adversely affects lithium-cob alt chemistry. This damages the battery and at the same time increases the risk of ignition and explosion of the electrolyte. It is best to use advanced chargers with the ability to adjust the supplied current and apply different settings for charging. The best charging method here would be the CC / CV algorithm - constant current / constant voltage (Constant current / constant voltage).
Cob alt batteries are badly affected not only by overcharging, but also by overdischarging. The peak threshold for discharge is 3 volts. If you continue to work on cob alt after reaching this voltage of the battery, it will spoil it, increasing the risk of ignition. Ideally, you should stop working on cob alt after 3.5 volts. Relation to lithium-cob alt chemistryshould be the most careful. Overcharging, overdischarging, excessively low ohms on discharge, physical damage will contribute to the deterioration of the chemistry, which will eventually lead to an explosion. In cases with very high current per charge and very low resistance, it can happen immediately. Nickel-cob alt chemistry is highly toxic. When ignited, it releases gases that are very harmful to he alth and can be fatal if inhaled.
Lithium manganese batteries
Lithium-manganese batteries are the most popular, primarily due to the stability of their chemistry with almost similar properties to cob alt batteries. Therefore, many manganese batteries do not have a charge controller, and at the same time, manufacturers proudly hang a “safe” flag on them.
Manganese batteries are able to work long and quietly under load (with a very low ohm). This, of course, is not good in any case, but unlike cob alt elements, manganese ones will last much longer in this case. Manganese elements have a good balance of capacitance and strength, but lose to cob alt in capacity. The precautions for charging IMR batteries are almost the same as for cob alt batteries. The maximum limit is 4.2 volts. The use of high currents per charge will not explode the electrolyte, but it will greatly spoil it. And this, of course, depends on the strength of the supplied current. The stronger it is, the faster charging will occur, but the worse it will be for chemistry. The recommended charging method is CC/CV. Another plusmanganese cells in that they are able to withstand a deep discharge of 2.5 volts. Be that as it may, you should not often bring a manganese battery to such a state.
This type of electrolyte is also characterized by the absence of an explosive effect. This is due to the use of graphite as an anode material. In a critical operating condition (very low resistance or very high current per charge), even an unprotected battery will produce gas, but will not ignite or explode.
In general, due to their average performance, 18650 lithium-manganese batteries are better in performance. Which batteries of this category to choose, you should look in the reviews separately for each of the manufacturers.
Lithium iron phosphate batteries
Lithium iron phosphate (ferrophosphate) are the safest of the lithium-ion battery family. This is their main difference. The stability of the chemistry of LFP batteries is even better than that of manganese batteries. This is due to the use of iron phosphate cathode, which has excellent thermal stability and no toxicity. Almost all iron phosphate batteries are not equipped with a charge controller, and it takes a lot of effort to bring them to an explosion or fire without physical damage. They are well tolerated by various abuses in work, such as very low resistance.
Ferrophosphate cells have the highest service life (2000 charge-discharge cycles) among lithium-ion. Fromcons - low capacity, about 50% lower than that of cob alt batteries, and about 15% lower than that of manganese batteries. Another feature of these batteries is the stability of the voltage during use, which fluctuates near the border of 3.2 volts until discharge. This property gives ferrophosphate batteries more advantages for using them in a series connection (if the batteries are assembled in a circuit, that is, in a battery). Iron-phosphate batteries have a lower current output than their counterparts in chemistry, but high-current ones can also be found among them. Iron phosphate batteries age slightly slower than other lithium-ion batteries, but as described above, they should not be stored empty.
When looking for information about which 18650 battery is best for a flashlight or a radio-controlled model, it is recommended to opt for batteries with this chemistry. Due to the properties described above, they are perfect for use in the batteries of these devices.
The chemistry of these power supplies allows you to safely charge them using an accelerated method. Ferrophosphate batteries are very resistant to overcharging. As for the discharge, its maximum allowable limit is 2 volts. Toward the end of operation, the stable battery voltage will drop sharply. Frequent discharge below this limit will quickly damage the battery.
Finally
This will complete the description of battery markings, technical characteristics of 18650, which ones are better, and different types of chemistry, we will finish. We hope this information helpsdetermine which battery is suitable for a particular device. The recommendations and characteristics given here are given in a very concise manner. Entire forums, websites and even books are devoted to batteries. The most complete information about them cannot be put in one article. We are not talking about the fact that to study them you need to know a lot of special terms and electrochemistry in general.
