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Lithium battery knowledge introduction

Published by admin 2024-04-07

The lithium battery model represents the external size of the lithium battery, for example, the first two 18 of 18650 lithium battery means the diameter of the lithium battery is 18mm, 65 means the length of the battery is 65mm, 0 means this battery is columnar. The more common lithium batteries used in torches are 18650, 21700 and 26650, in addition to these three common models there are 26800, 18350, 26350, 14500, 16340 and other models. Try to buy torches that use 21700 and 18650 lithium batteries. Other models of lithium batteries are also sold but are rarely produced by major manufacturers and are of varying quality.

3.7 volt lithium battery



The rated voltage of these lithium batteries is generally 3.7V, there are a few 3.6V, when fully charged the voltage can reach 4.2V, when discharging the voltage will continue to reduce until put to 2.5V completely dead, generally 2.8V as the discharge cut-off voltage. The voltage of cylindrical lithium batteries for torches is generally common, so there is no need to pay attention to voltage parameters.


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Capacity is one of the most important indicators of lithium batteries, the higher the capacity of the same type of lithium battery, the longer the range. The highest capacity 18650 lithium battery you can buy is Sanyo Big Red Robe, the capacity can reach 3500mAH (3600 but can not buy), higher than this value are false label; 21700 lithium battery capacity can reach 5000mAH, 26650 is currently the highest capacity of 5500mAH. some manufacturers will print the capacity and other parameters on the battery skin, but most of the battery is not printed on any parameters. Most batteries do not have any parameters printed on them, at most they have a model number printed on them. The only way to get the true capacity of a battery is to measure it yourself. Another point to note is that the actual capacity of the battery is related to the current, internal resistance and the environment, the manufacturer's nominal capacity value is measured by 0.2C small current discharge (for example, 3500mAH battery with 0.7A discharge test), the usual use is generally not up to the nominal capacity.


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Discharge current and multiplier

lithium battery discharge current and multiplier is also one of the important indicators to determine whether the battery is suitable for your torch, when buying a battery should first look at the discharge capacity to meet the requirements, and then to consider the capacity. Discharge current is divided into continuous discharge and peak discharge. Continuous discharge means that the battery can be discharged at that current for a long time under standard conditions, while peak current is the current that the battery can withstand occasionally, for a moment, and cannot be discharged at peak current for a long time.



In addition to the discharge current, some battery parameter tables are marked with a discharge multiplier, for example 5C, 10C means 5 times, 10 times. Discharge multiplier C number = battery capacity / 1000, for example, 3000mAH lithium battery, 5C is equal to 5 * (3000/1000) = 15A discharge current, 10C is 10 * (3000/1000) = 30A discharge current. Many people like to remove 18650 batteries from rechargeable batteries and laptops to use, it is not recommended to do so, these batteries are generally capacity type, unless you can measure the discharge performance of these batteries yourself.



About internal resistance


Internal resistance is the most important indicator of lithium batteries, which determines the overall performance of lithium batteries. The internal resistance can be seen as the resistance of the battery itself, and the driver board and lamp beads in series in the circuit. As we all know the formula for power is P=I²R, the greater the value of resistance R, the more energy the battery itself loses, this loss is consumed in the form of the battery's own heat. The only way to get an accurate internal resistance value is to use an internal resistance tester such as the YR1030, or refer to the manufacturer's published battery data sheet.


The lower the internal resistance of a Li-ion battery, the lower its own losses and the better its discharge performance. For 18650 batteries, those with internal resistance below 14 are generally high performance and high rate batteries, and those with several tens of milliohms are generally capacity batteries, and with such a large size, capacity and performance cannot be combined, so when purchasing, you must first look at the discharge capacity. If you use a high internal resistance battery with high current discharge, the power consumed by the battery itself will rise sharply by the formula P=I²R, and the battery will heat up quickly, and the discharge performance of many batteries will be greatly affected by the temperature, which will seriously affect the life of the battery and will even be dangerous if discharged for a long time.


Many electric cars actually use our column lithium batteries first in parallel and then in series, whether in series or parallel require the capacity and internal resistance of each battery in order to form a group, if you use a torch using multiple batteries, whether in series or parallel, but also to use the same batch of batteries (internal resistance and capacity to be the same), to avoid individual batteries to drag the legs of the whole group of batteries. The vast majority of these lithium battery manufacturers are not in the retail business, in fact, most of the so-called brand new batteries we buy are actually defective and inferior products that flow out of the manufacturers after screening, but the good thing is that the requirements of torches are not as high as car batteries, so it doesn't matter.


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For example, the internal resistance is different between 3.2V and 4.2V. The higher the voltage, the lower the internal resistance.


panasonic ncr18650pf


About tips and flats

When buying these cylindrical batteries, you should be aware that there are pointed and flat-tipped ones, as shown in the picture, the pointed one means that the positive terminal of the lithium battery is protruding. The first way to tell is to ask the merchant, or to unscrew the head of the torch and see for yourself. Generally speaking, if the positive electrode of the torch is a spring, then this torch tip, flat head battery can be used, of course, there are a few torches in order to slim down only support flat head battery; if the positive electrode of the torch is not a spring, flat head battery may not be able to contact with the positive electrode, this torch can not use flat head battery, and flat head battery also ooh ah series use. Some friends may want to buy small magnets to suck on the positive pole to make the flat head into a pointed battery, small power torches can do so, high-powered then the magnet will increase the internal resistance, the impact is larger.


li ion voltage


About batteries with protective plates

Many DIY torches and low-end brand torches do not have built-in battery protection, which may accidentally drain the battery or affect the life of the battery, so some friends think of buying lithium batteries with built-in protection plates. This type of lithium battery with protection plate is actually a protection plate in series with the negative terminal, which has a high internal resistance and is not suitable for high power discharge, except for branded lithium batteries with protection plate; the battery with protection plate is also a cut longer than ordinary batteries, so some torches or chargers cannot be put in. I would not recommend using a lithium battery with a protective plate on a torch. If you care about battery life, try to buy a torch with a low-voltage battery protection circuit.


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About buying brand new or dismantled batteries

Batteries are very deep, so I recommend that newcomers or those who don't want to toss and turn buy a branded torch. As mentioned before, the big brand lithium battery manufacturers generally do not do retail business, and many of the brand new ones you can buy on the market are defective, and there are even ordinary batteries with a new cover that pretend to be branded batteries. Occasionally find a regular shop to sell, the price is ridiculously expensive, such as a brand new SONY VCT6 need about 50 yuan, buy a few sections than the torch is also expensive, so many players are using dismantled batteries. If you're looking for a reliable business to buy a dismantled battery, you'll find that a good system can be as durable as a brand new one. The dismantled batteries are usually spot welded and the negative terminals have obvious polishing marks. It is not recommended for non-gamers to buy dismantled batteries.


1s lipo charger


About the charger

If you don't want to toss and turn, it is recommended to buy a torch with direct charging, which is much more convenient and does not require the batteries to be removed for charging. There aren't any big brand name chargers out there, and most of the chargers for brand name torches are OEM. The one I bought is called Liitokala, and it's been in use for three or four years. It can charge four batteries at the same time, and supports 18650, 21700, 26650, 18350 and other battery types. There is a brand called "Nengyeon" that also does a good job, but the price is too high.


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If you have more than one type of battery on hand, make sure you look at the type of charger you support.


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About the choice of test equipment


The internal resistance of Li-ion batteries is one of the most important parameters, if you like to toss the battery as I do, then it is necessary to buy an internal resistance tester, the average user does not need to buy. Some chargers come with an internal resistance test function, but basically they are not accurate.


4s voltage


In addition to measuring the internal resistance, you also need to test the capacity, some chargers also have capacity testing function, capacity testing is not so high technology, if the charger is the battery is full and then discharged capacity measurement method has some reference value, but for the power battery such a test has no meaning. Charger with capacity measurement function discharge current are very low, can not use high current discharge to test the performance of lithium batteries under high current, so we have to use a professional load on the test, such as the use of EBD-A20H, the highest support 20A discharge. Note that test stands generally have to be purchased additionally.


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About storage and maintenance

Lithium batteries do not require high environmental requirements for storage, so it is recommended that they are stored in a cool and dry place for a long time. When the torch is not used for a long time, the battery should be removed. Most torches will have a weak current consumption, and if not used for a long time, the power may be discharged, affecting the battery life. It is also important to note that lithium batteries should be stored at their rated voltage of 3.7V for a long time.


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Common lithium batteries review

Next I took some time to review some common lithium batteries on the market, as a reference when buying.

Panasonic 18650

Panasonic 18650B is one of the most common 18650 batteries, there are 18650B, 18650A, 18650BE and other models, there are also more dismantled and counterfeit ones on the market, so be careful to identify them. Most Panasonic batteries are capacity batteries, for example, this 18650B has a capacity of up to 3400mAH and an internal resistance of 30-40 milliohms, I have only used this for 2 years so the internal resistance is a little higher. Panasonic batteries are characterised by high capacity, long cycle life and relatively high price.


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As a capacity battery, the maximum discharge current supported by Panasonic 18650B is only about 5A, which is not of high practical value for strong torch players and cannot be used for slightly more powerful torches. If you use this type of capacity battery as a power battery, there is no point, I have done a test for you, using 10A current to discharge, as shown in the picture, only 1257mAH of power was released, and the battery heat is very high, so this battery is only suitable for about 3A current. This battery is only suitable for low power torches and devices.


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Sanyo NCR18650GA

The Sanyo NCR18650GA is commonly known as the "Big Red Robe", with a red cover and a capacity of 3500mAH, making it the largest capacity 18650 battery available (there are 3600mAH ones available, so basically you can't buy them). The Sanyo Big Red is also a capacity battery, with an internal resistance of around 25 milliohms, but with a stronger discharge capacity than the Panasonic 18650B:.


panasonic cr1620


Tested with a charger, it can discharge 3450mAH at 1A current and 3550mAH at 0.7A current.


18650 lipo


Many merchants label the Sanyo Big Red Robe as a "power battery", and the continuous discharge current can reach 10A, but in fact it is impossible to reach 10A, after all, the capacity has reached its limit, with the current technology simply can not do that high discharge performance. I specifically used 10A current discharge test, as shown in the picture, can release 2570mAH of power, compared to the Panasonic is to double, I think it is called "semi-power" is not a problem, for continuous current in about 5A torch, of course, your torch usually only open in bright, occasionally will use about 10A current Not a problem: LGABHG2


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LG LGABHG2, referred to here as HG2, is a capacity of 3000mAH 18650 power battery, can continue to discharge 20A. HG2 general new internal resistance in 15mΩ or so, I have a few of these due to the use of a year measured at 16 milliohms or so: I used 20A current to test.


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I used 20A current for testing and measured that the HG2 discharged 2715mAH at a full 20A current, which is moderate and can be used in torches and devices with high requirements for continuous discharge.


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Samsung 30Q

The Samsung 30Q is also an 18650 power cell with a capacity of 3000mAH, which can be discharged at a sustained current of 20A at a moderate price. 30Q has an internal resistance of 12-14 milliohms depending on the batch.

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The 30Q has a capacity of 2887mAH under 20A continuous discharge, which is much stronger than the LG HG2 above, and of course much more expensive, also suitable for high power torches.


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VTC6 is also the capacity of 3000mAH 18650 power battery, continuous discharge current up to 30A. VTC6 and LG HG2, Samsung 30Q capacity are 3000mAH, but VTC6 internal resistance is the lowest, the strongest performance, internal resistance is only about 10 milliohms. The one I have is a dismantled one, so the capacity is measured at 14 milliohms


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Under 20A continuous discharge, the sony VTC6 can discharge 2936mAH, which can be called the strongest 18650 power battery on the earth, and there is no one else that can match the VTC6 with the same capacity.


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Samsung INR21700-50E

The Samsung INR21700-50E, referred to as 50E, is a 21700 battery with a capacity of 5000mAH and a continuous discharge current of 10A. 10A current can only be considered a capacity battery in a 21700 battery, with an internal resistance of around 15mΩ.


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Using 10A continuous current for discharge, the measured discharge capacity is 4740mAH, which is suitable for use in torches with low power.


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Samsung INR21700-48X Generation 2

The Samsung INR21700-48X, which we will refer to as the 48X, has a capacity of 4800mAH, can be discharged at a continuous current of 20AH and is considered a 21700 power cell with an internal resistance of around 13 mΩ.


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The 48X discharged 4393mAH at 20A, which is a moderate overall performance.


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Panasonic NCR21700T

The Panasonic 21700 is a capacity 21700 battery built by Panasonic for Tesla, with a capacity of 4800mAH, an internal resistance of around 12 milliohms and a continuous discharge current of 10A, it is a capacity 21700 battery. Tesla batteries generally do not have a cover, so the cover of the Panasonic 21700 battery must have been put on by the vendor itself.


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The Panasonic 21700T discharged 4534mAH at 10A, which is suitable for low power torches.


12.8 v lithium ion battery


Aoray Custom 21700

This is a custom made Aoray 21700 battery with built-in protection plate, 3.6V, 5000mAH capacity, taken from a 4200 lumen Aoray Explorer 3PRO torch. Note that Aorai's custom batteries can only be used in their own torches.


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Using a 10A current measurement, this custom Aoray 21700 battery eventually released 4665mAH of power. A battery with a built-in protection plate has a discharge capacity of 10A and a 4600+ capacity output, no wonder they are sold at such a high price.


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Tesla 21700

This Tesla 21700 was previously bought in a treasure, no specific model, the outer skin is also the merchant's own on, the capacity is claimed to be 4800mAH, internal resistance 14 milliohms, continuous discharge 10A, then see the price is cheap, as long as more than 10 yuan a section to buy a few: 10A current discharge.


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The capacity, internal resistance and discharge curve are similar to that of the Panasonic 21700T, so I guess it is actually the same batch of goods.


li ion cell voltage


Riksun LR2170LA

The LR2170LA is a 4000mAH battery with an internal resistance of 8 milliohms and a continuous discharge current of 30 A. As a domestic battery brand, the quality control is not bad, and the brand new batteries available on the market may be slightly defective, but they are better than dismantled or skinned batteries.


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Using 20A continuous discharge, the Li Shen 2170LA outputted 3742mAH of power, which is not as good as the Samsung 48X at 20A current, but the Li Shen can also support up to 30A continuous discharge, which is perfect for some single violent torches, such as a single 21700 battery, 10,000+ lumens torch:.


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Riksun LR2170HP

The LR2170HP is a more violent power cell than the 2170LA and can achieve a horrific 20C continuous discharge. 2170HP has a capacity of only 3000mAH and a 20C discharge, i.e. a continuous 60A discharge, with a measured internal resistance of only 7.29 milliohms.


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Using a 20A continuous discharge, the 2170HP ended up with an output of 2340mAH. As my tester is only capable of 20A discharge, it is estimated that the capacity is only 1,800mAH if discharged at 60A.

3.7 v lithium battery 18650


Panasonic 26650A

Next up is the 26650 battery. It is said that Panasonic does not produce 26650 batteries, which is not clear, but the price is cheap I bought one to test, look at its parameters is 5000mAH capacity, internal resistance is 17.83 milliohms.


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Measured at 10A current released 5032mAH capacity, and the description of the match, but I still do not recommend buying, mainly because I do not know how cycle life. Here I recommend buying the domestic LiLang 26650 battery, which has a capacity of 5500mAH.


3 volt lithium battery cr2032


Nato 26650

There are only two 26650 torches on hand, so I had to take the 26650 charge from the Nato 2000 lumen torch to do a test. This battery also has a capacity of 5000mAH, with an internal resistance of 17.4 milliohms, which is not too far off from the one above.


3.7 v 18650 lithium battery


The measured output capacity is 5032mAH at 10A, the curve is similar to that of the skinned Panasonic, so it should be the same batch.


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SoSHine 18350 battery

One last test for you on the 18350 battery. There are many torches that can be replaced with short barrels using 18350 batteries to reduce their size, such as the Thunderbolt EDC18 and so on. However, there are few major manufacturers on the market that make 18350 batteries, and all of them have small capacities and poor sustained discharge performance. My Soshine 18350 battery has a nominal capacity of 1000mAH and measured internal resistance of 26.5 milliohms.

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This battery discharged 794mAH at 10A current, this 18350 battery actually performed very well, you should know that most 18350 batteries are unable to discharge at 10A current, other 18350 batteries I bought before put 200mAH at 10A and they were gone.

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Technical Support: Magic Lamp