Lithium ion cell 18650 test

4800mAh, 5200mAh, 6800mAh, 8800mAh in one LiIon 18650 battery!?

4800mAh, 5200mAh, 6800mAh, 8800mAh. With such “fantastic” characteristics they sell 18650 battery cells in stores in our city!
The appearance of such powerful 18650 lithium-ion battery cells on the battery cell market could not interest us. Even the leader in the production of LiIon batteries, Panasonic, which produces the NCR18650G with a capacity of 3400 mAh, looks very pale next to them. We decided to conduct a test and publish the data obtained!
Using a software and hardware complex for testing battery cells, we can emulate various operating conditions of battery cells: charging, discharging, different currents and voltages.
As with testing batteries, we also checked LiIon 18650 3.7V battery cells for the amount of energy output and its cost. In other words, we found out which 18650 cells are profitable to buy, and which 18650 batteries have cheaper or more expensive electricity.
We tested all elements according to the following scheme:
1. Charge the battery cell to a voltage of 4.2 volts.
2. Rest the element without load and without applying voltage for 5 minutes.
3. Discharge the element to a voltage of 2.75 volts with a current of 0.5 amperes.

We purchased 1 piece of each model in different retail stores in Irkutsk:*
- HANGLIANG 18650 6800mAh - Price: 250 rub.
- BAILONG 18650 8800mAh - Price: 380 rub.
- UITRAFLRC 18650 4800mAh - Price: 250 rub.
- XBAL G 18650 8800mAh - Price: 350 rub.

For comparison, the following were used in the experiment:*
- - Price: 225 rub.
- China ISR18650P 2200mAh - Price: 280 rub.
- - Price: 300 rub.
- SAMSUNG ICR18650-24E 2400mAh used - Price: free on promotion.

Battery cell testing results
LiIon 18650 3.7 volts,
discharge up to 2.75 volts, load 500mA.

*prices indicated at the time of writing, June 20016.

After test autopsy

During testing, we paid attention to the low weight of elements from HANGLIANG, BAILONG, UITRAFLRC and XBAL. On average, the weight of one element was only 25 grams. Typically 18650 cells weigh around 40-45 grams.
We opened one of the elements. Approximately 1/4 of the battery was free. The electrode winding is not dense and has interlayer gaps.
Thus, we can conclude that one of the signs of a battery with a fictitious capacity is the light weight of the element with a capacity indicated on it of more than 2500-3000 mAh.

Power supplies for various devices have long been part of our lives. They help keep communication lines running when the usual conveniences are too far away. An LED flashlight will not work without a battery. Therefore, today there is a rapid increase in the production of new batteries. The 18650 battery was developed to power laptops, hand-held power tools and other machinery.

The cathode for such elements is made of various materials. Lithium 18650 batteries are divided into several types, which are directly dependent on the material from which the cathode is made:

• LiCoO2. This battery is most widely used due to its large capacity. Manufacturing is carried out in accordance with the Li-ion technological process.
• LiMnO2. High current 18650 lithium manganese batteries. The discharge current, with a small capacity, reaches 5–7 A.
• LiFePO4. These lithium ferrophosphate batteries are far superior to other models. But they differ in minimum voltage and low capacitance.

Lithium-cobalt elements are widely used. They differ from similar elements in their large capacity. The service life of such a battery is much longer.

Description and characteristics of the 18650 battery

They are distinguished by their cylindrical shape and are available in several types:

• finger - AA;
• pinky - AAA.

The dimensions of the 18650 battery are slightly larger than conventional batteries:

• length – 66.5 mm;
• diameter – 18 mm.

Technical Parameters:

• output voltage is 3.78 volts.
• Capacity - 2000–3200 mAh.

The 18650 lithium ion battery has found constant use in devices that require maximum capacity:

• Laptop batteries.
• All kinds of modifications of LED lights.
• power bank.
• Chargers for mobile gadgets.

What is the meaning of the designation printed on the surface of 18650 batteries?

To figure it out, let's take a lithium-ion battery, brand ICR18650-26F M.

• “I” - this symbol marks all elements of this type, the production of which is carried out according to the same technological process.
• "C" - indicates the material from which the cathode is made. For example, M stands for manganese, F for iron phosphate, C for cobalt.
• "R" stands for battery.
• 18650 - divided into two sections - 18, 65. Indicate the diameter and length.
• 0 – designation of shape, meaning cylinder.

Important! Battery labeling does not have the same meaning. Each manufacturer has it individually, so it can have big differences.

To extend the life of a good battery, professionals advise adhering to several important rules.

Never allow the battery to become completely discharged. 18650 does not have a "memory effect". Therefore, there is no need to wait until it is completely discharged. If the charge level drops to zero, the battery life will be greatly reduced. For example, a zero capacity charge can be performed 400–600 times. If the residual capacity reaches 15%, the number of charge cycles will greatly increase to 1000–1200.

The battery must be completely discharged once every three months. Testing has shown that fully charging a lithium-ion battery is pointless. Its capacity decreases and its service life decreases. Professionals recommend completely discharging the battery at least once within three months, and then charging it again.

Interesting video about testing 18650 batteries

A full charge level must be maintained for 10 hours. As a result, the container will “swing” perfectly and its original performance will return. In any case, regardless of whether the “memory effect” exists or not, the charge threshold remains unchanged.

It is very important to store the 18650 battery properly. It is best to store the cells when the charge level does not exceed 35-50%. The room temperature must be maintained at 15 degrees. The battery should not be exposed to direct sunlight. The battery is afraid of ultraviolet radiation.

It is unacceptable to store the battery in a discharged state for several months. It will simply stop working. We'll have to get rid of him. A charged battery can be stored much longer, but within certain limits. Otherwise, history will repeat itself, it will simply fail.

The 18650 battery should not get very hot. High temperatures cause enormous harm to the condition of the battery. Overheating is associated with several reasons:

• Direct exposure to sunlight.
• Long-term operation;
• Heat sources, such as a radiator, are located near the elements.

Always remember! The 18650 battery cannot be used at temperatures of 40 - +50 degrees.

The battery should be charged regularly. Otherwise, even a very good battery will become unusable much sooner. Therefore, it is very important to follow the basic rules for charging lithium batteries.

The initial charge voltage should not exceed 0.05 V. At the end of charging, it rises to 4.2 V. The specified parameters are considered the safest for such batteries.

Charging can also be carried out if the charge current is in the range of 0.5 - 1 A. The best indicator is 0.5 A, if the current increases to 1A, charging will proceed a little faster.

Experts do not advise specifically speeding up the process unless it is particularly necessary. It takes no more than three hours to charge the battery. Exceeding this period may cause a change in the chemical structure of the battery.

Only if the system is equipped with a control mechanism can the charging time be violated. The controller itself will determine when it is necessary to turn off the charge.

The 18650 battery should not drain to zero. After this, no charge will be able to return the battery to its previous technical characteristics. Therefore, you need to constantly recharge the product and monitor its condition.

How to correctly determine the polarity on a 18650 battery

If you compare ordinary batteries with lithium ones, you will notice that the latter’s positive and negative terminals do not have much difference. However, it is quite easy to see where the plus and where the minus are. The positive contact has several small holes (3-4 pieces); it protrudes slightly forward. The negative contact has a completely flat surface.

I welcome everyone who stopped by. The review will focus, as you probably already guessed, on the removal of protection boards from lithium-ion batteries of the 18650 form factor, in particular Sanyo UR18650FM 2600mah and Panasonic NCR18650PF 2900mah. There was a review on Muska where the author put protection, but there seemed to be no reviews of removal. I hope this review will be useful to someone. I probably agree with those who say that this operation is a mere trifle and it was not worth writing a review about it. But, as practice shows, some are afraid and do not dare to remove the protection. If you are interested, please see cat.

A small educational program on Li-ion batteries in a free interpretation:
First of all, the battery is the primary power source, i.e. it generates energy itself. In our case, it converts chemical energy into electrical energy. The first lithium-ion battery was released by Sony in 1991 (with ViKi). If anyone thinks that these batteries are something unusual and even dangerous, then I dare to reassure you, these batteries have long been installed in various electronic gadgets, from phones to laptops, the batteries just have different form factors.
In mass production, three classes of Li-ion batteries are used (based on the cathode material, the second letter in the marking):
1) lithium-cobalt LiCoO2 (the most common, the highest capacity among Li-Ion)
2) lithium-manganese LiMnO2, LiMn2O4, LiNiMnCoO2 (better known as high-current (INR), capable of delivering currents of 5-7C to the load, which are usually inferior in capacity to the former)
3) lithium ferrophosphate LiFePO4 (excellent batteries undervalued by the market, which in all respects are undoubtedly superior to the first two types, except for operating voltage and capacity, it is even lower than that of INR)
As they say, all three classes are tailored to perform specific tasks and have their pros and cons.

Since there are no uniform battery labeling standards, all manufacturers label them differently. But ideally it should be something like this:
1) the first letter is the manufacturing technology (I - lithium-ion technology)
2) second letter - type of chemistry, cathode material (C/M/F - cobalt/manganese/iron phosphate chemistry)
3) third letter R - battery (rechargeable)
4) five digits - form factor (the first two digits are diameter, the next two are length, the last digit is the shape of the acca (0 - cylindrical))
- 10430 (everyone’s familiar “little fingers”)
- 14500 (everyone’s familiar “fingers”),
- 16340 (size like a CR123 battery),
- 17335 (not common)
- 18500 (also not very common)
- 18650 (the most common form factor on the market),
- 26650 (enlarged, came to the market from the company A123 Systems, which produces lithium ferrophosphate batteries)
- 32650 (absolutely monsters, only for stationary devices, weight almost 150g)
- plus unofficial f/f with protection boards, for example 18670...
5) letters/numbers - specific marking of the container (different for all manufacturers)

An example of marking, but as a rule, it is different for all manufacturers:
- Samsung ICR18650-26F (lithium-ion battery with the usual cobalt chemistry, f/f 18650 with a capacity of 2600mah)
- Samsung INR18650-20R (lithium-ion battery with manganese chemistry, i.e. high-current, f/f 18650 with a capacity of 2000mah)

Own designations:
Panasonic NCR18650PF (NCR is a type of cobalt chemistry, something between the first and second classes, i.e., in simple words, LiNiCoO2 chemistry, without the use of maranz. As if it does not fit a certain class, a kind of symbiosis has turned out. The advantage is high energy density with low thresholds up to 2.5-2.75V). This battery uses LiNiMnCoO2 chemistry, that is, it is already IMR high-current based on manganese, but the manufacturer left the old markings.
Sanyo UR18650FM - the information may not be accurate, but I came across information that Sanyo does not produce batteries for retail sale, and therefore does not bother with labeling. It produces cans for large electronics manufacturers, so the labeling is purely “for itself.” Perhaps, according to the company’s internal designations, UR and F(M) mean type, chemistry and capacity, at least there is no information in the datasheets (only that this is the model marking). And this is a lithium-ion battery with the usual cobalt chemistry, f/f 18650 with a capacity of 2600mah.

Now briefly about what protection is and where it is usually located:
Protection is a special board, often located on the negative terminal of the battery. It protects the battery from short circuit, overcharge and overdischarge, breaking the supply circuit. Characterized by three parameters:
- cut-off voltage when charging (4.25-4.3V)
- cut-off voltage during discharge (2.4-2.7V)
- throughput current (mainly depends on the number of mosfets on the board)
As an example, a datasheet for a simple protection:

What is the board:







Photo of protection on the negative contact (most common):




Photo of protection on the positive contact:

Some important notes on Li-ion

There are no Li-ion batteries in the 18650 form factor with a capacity of more than 3600mAh. All ****Fire with bright numbers 4000-5500mah are just fakes. Inside there are either rejects/recycling batteries, or batteries of a smaller capacity, and sometimes of a completely different form factor (inserted into the 18650 like in a Russian nesting doll with sand for weight), covered with colorful shrink film. At the time of writing, only the Panasonic NCR18650G had a maximum capacity of 3600mah. Even batteries with increased voltage to 4.35V do not reach this capacity.
Pornoslonik at 3600mah (not yet found in retail):


But UltraFire at 2400mah and 3000mah:




- Large manufacturers do not produce protected batteries. Their factories always produce unprotected cans for use in battery assemblies and other devices. Other companies install the protection board, often covering the can with their proprietary heat shrink.
As an example of Keeppower, just above there was unnamed China


As we can see, both batteries have the well-known Panasonic NCR18650B inside, only the first one has the highest quality protection and the banks are from more successful batches, while the second one is typical of China.
- manufacturers divide the elements inside the battery into three quality classes (this information is not included in the battery labeling, only within the manufacturing company)


- a convexity (notch) in the area of ​​the positive contact of the battery is not protection; it is a structural feature of all Li-ion. Also, the bulge on the positive/minus contact itself does not indicate the presence of a protection board, it is just the type of contact.


This is the same notch that some people mistake for a protection board):


Two identical unprotected Panasonic NCR18650B with different contacts:




- Evaluating a battery only by its capacity is a big mistake. You need to compare based on the stored energy, as well as the lower voltage threshold. For example, the very popular NCR18650B porno with a discharge current of 0.5A shows a capacity of 3270mah (11.85W), and with a 3A discharge it is already 3100mah (10.7W), but a specific voltage drop is observed. In addition, most devices cannot discharge the battery below 2.9-3V and simply turn off, this must be taken into account.
- Li-ion batteries do not have any memory effect, so they can be charged without waiting for them to discharge to zero. According to information from the Internet, if you charge the battery at 70-80%, i.e. do not discharge below this threshold, then the number of cycles increases from 500-600 to 1000.
- Li-ion batteries have some self-discharge, so to reduce the impact of this effect during long-term storage, batteries should be stored in a slightly discharged state in a cool place (15 degrees). Those. The charge level should be around 75%.
Loss of capacity during storage (with ViKi):


- periodically you need to discharge the battery, once or twice every couple of months.
- Li-ion batteries do not like low and high temperatures, so in the cold, ordinary lithium drains the capacity greatly, and when exposed to high temperatures, the resource is greatly reduced.
- absolutely all Li-ion batteries have a safety valve to release excessive pressure when the can overheats.
- Well, from personal experience. The devil is not as scary as he is painted. I accidentally shorted the LG can from my laptop. It was a bit of a search, nothing more. No explosion, etc., as ardent fans of protected batteries write about

So, enough chatter, let's get back to the main topic, which is removing the protection board.
Why is “castration” actually needed:
- To reduce energy loss on this board. For example, in single-can flashlights this is quite critical, so it is preferable to use batteries without protection there, because all conductors and protective elements are something other than resistance. And at high currents, even a tiny resistance can greatly spoil the picture. For example, with a current of 2.8A in some area with a resistance of 0.2 Ohm, we will have a drop of U=I*R=2.8*0.2=0.56V. Stabilization on mikrukh AMC7135 (national Nanjg drivers) will continue until the voltage on the bank drops to 3.8V (approximately), then the brightness of the flashlight will gradually decrease.
- For DIY device assemblies. Suppose the battery built into the power bank (PB) has a capacity of about 1 Ah and, therefore, the PB is of little use and you decide to replace the built-in battery. But having disassembled the power bank, we saw that the current collectors were welded to the battery contacts by spot welding, and after reading on the Internet about the dangers of soldering the battery contacts, we came to a dead end (the new battery will have to be soldered to these current collectors). This is where this operation will help. If the power bank has built-in protection against overcharge/overdischarge, then to get out of this situation, we simply buy a battery with protection. When removing it, we save the conductors welded to the battery contacts and solder the current collectors of the power bank to them. As a result, we do everything safely and preserve the appearance of the battery (you can later replace it with a more capacious one, and use this one for other needs, simply tearing off the conductors and there will be no solder on the contacts).
- The protected battery is not included in the flashlight/charger/PB/other device. This applies to budget shitty fireers, there is such a problem, or budget chargers, for example, the Miller ML-102, which I recently wrote a review about. They are often designed for unprotected banks (there are quite a few similar devices).
- The device consumes excessive current and due to this, the current protection is activated. In ordinary boards, on average the shutdown threshold is 5-6A, but it can also be around 2.5-3A (in a powerful 2.8A flashlight this will already be a problem).
- The protection board does not operate correctly, i.e. the charger finishes charging before or turns off earlier when the device is discharged. This also happens, especially with Chinese protection. For example, a branded charger fills, as expected, up to 4.2V, but the protection board responds earlier, say at 4.18V, which means the battery is slightly undercharged (although the boards are designed for 4.25V). It's rare, but still unpleasant.
- To reduce the self-discharge of the can. The board consumes a small current in sleep mode.
- Batteries with protection are safer, which means they are more in demand on the market. Consequently, they do not sit in store warehouses and are constantly updated. Due to the ban on lithium transportation, the number of stores guaranteed to send lithium is noticeably reduced. And there may be a situation where unprotected batteries are needed, and the store’s assortment includes only fresh protected batteries and stale unprotected ones (or none at all). And as you know, lithium ages quickly, so the choice falls on protected ones, although they are not needed. And with small movements, they turn into unprotected (here, of course, there is a slight overpayment for protection, but you have to sacrifice something, either durability or cost).
- Well, and most recently, when the protection board simply burned out/damaged. Nothing works with her at all.
In general, there can be a lot of reasons, or it can be trivial, your hands are just itching...

So, our students:
Sanyo UR18650FM (bought for a finished shitfire without overdischarge protection)
+ very high quality (it’s not for nothing that they call it folk)
+ good discharge curve (behaves well with current load)
+ inexpensive
+ no fakes
- the capacity is slightly less than declared (especially at current load)
- weak (thin) positive contact (in devices with a rigid spring it bends)
- not frost-resistant (new version UR18650ZY - frost-resistant)
- sometimes you come across stale ones

Castration Sanyo

Photo with protection:


So, first we cut off the edge of the folded heat shrink. Next, we decide whether this external heat shrinkage is needed (it can be useful for additional protection, as well as to prevent the can from flopping around inside a device, for example, a flashlight).


If you decide to leave it, then carefully pick out the plate holder. The edges of the heat shrink will dangle, then you can heat them and they will press against the body. I don't need protection, because... The battery will be used in the Convoy M1 flashlight, and additional energy losses are not needed there, and it also has overdischarge protection.


We tear off the plastic washer (it looks like I didn’t take a photo of it), but you can leave it as is if you need a convex positive contact:


I didn’t need a convex contact, so carefully bend the positive contact with a screwdriver (it is important not to short-circuit the positive contact to the negative body):


As you can see, the positive contact is held on only one current lead and is pressed with a plastic washer with heat shrink:


Because My outer heat shrink was already worn out, so I decided to cover the jar with new heat shrink. Therefore, we simply rip off the old one:


We see a conductor glued to adhesive tape (yes, yes, you can’t just push it out from under the old heat shrink):


Let's tear off all this stuff:


We observe the remains of the glue that was used to glue the plastic washer. The glue can be easily removed with alcohol/acetone:


We borrow a regular hairdryer from our wife/friend and heat up the heat shrink. Anyone who has a hair dryer/soldering station is in trouble. They do everything efficiently and quickly. All irregularities will be pulled together. It is important here not to heat the contact too much; a couple of seconds is enough for the heat shrink to shrink.


This is the protection board that was installed in the People's Bank with BIC:


All protective elements (the puck has disappeared somewhere):


If desired, we pack the jar in new heat shrink. You can buy it here
To do this, we cut off the new heat shrink at a right angle, leaving a margin of 3-4 mm on the sides. If the ends of the tube are crooked, it will not lie flat when heated. Because the tube is sent in a twisted state (reel), then when you put it on the jar, you should not smooth out the sharp ends, otherwise after the “shrinkage” two unsightly stripes will remain along the battery:


Warm it up carefully. The main thing is to move the hairdryer smoothly and not to jump from one place to another, otherwise there will be small “spots”:






That's it, the battery is ready for work and defense:

Now it’s the Panasonic NCR18650PF’s turn (bought to replace the built-in battery in the Power Bank)
+ good quality (Sanyo is a subsidiary of Panasonic, they merged in 2009)
+ good current output (this is a high-current IMR battery, capable of delivering up to 10A)
+ quite affordable price for such a capacity
+ reinforced positive contact
± low discharge threshold of 2.5V (similar NCR18650PD has a discharge threshold of 2.75V)
- not frost-resistant

Castration Panasonic

Photo with protection






In my case, current leads were important to me, because... in case of an unsuccessful attempt to assemble the PB, the battery would be used in the flashlight, and the tinned contacts on the battery are not good. In principle, there is nothing complicated in direct soldering directly to the contacts, the main thing is to have a 40-60W soldering iron, flux and do everything quickly.
So, we rip off the heat shrink:








Because I needed current leads, so I bit them off with side cutters to the very root, i.e. at the board itself:




Using a thin screwdriver, or better yet, plastic cards, disconnect the plastic washer:


If you need a convex contact, as I wrote above, then carefully break off the down conductor by numerous bends and put the washer back. In my case, I don’t need it; with such a contact, this battery simply does not fit into the cylindrical PB, so we tear everything clean off:




We bite off the long conductor, it will still be useful in the future PB:


Here's what happened:




And here was the following protection board:

This battery will be wrapped in heat shrink along with the intestines of the PB.

General Notes:
Often, you can simply remove the protection contacts (plus and minus) and the board itself, and leave the transparent/colorful heat shrink along with the conductor (yellow stripe along the body) as additional protection for the battery case. The conductor itself cannot be pulled out from under the heat shrink; it is glued to the tape. You can solder anything to the contacts of the protected battery; there is a gap there, so the can itself is not in danger of overheating. The protection must be removed carefully, without short-circuiting the conductors.

Actually, why did I remove the protection? My first flashlight with a powerful LED was a cheap shitfire. Later, having felt the flashlights, I purchased better ones, but these cheap ones, although they were improved, were still not up to the level of a good product. Therefore, it was decided to put them in the garage/garden. They were rarely used and installing a driver with protection in them was not entirely advisable. Therefore, a basic stabilizer was made without overdischarge protection (cheap and cheerful), and using a can without protection in such a flashlight was dangerous. That's why batteries with protection were purchased. But recently the fleet of flashlights has been replenished and the modified flashlights have retired. But banks with protection turned out to be unnecessary. This is all about Sanyo. The story with the can of pornoslonika is a little different. It was purchased as a replacement for the battery built into the PB. Maybe I’ll tell you how I installed the porn elephant in the PB in the next article...

And more additional information on batteries:
Photo of discharge in comparators:
Let's compare our players with their brothers who have the best price/performance ratio


Because I don’t know how to insert a large photo into the review, so I’ll explain:
Discharge current 3A to 3V:
- The undisputed leader LG ICR18650D1 3000mah 4.35V (10Wh, the voltage holds perfectly, the capacity is 3000mah, i.e. in theory it should hold 3A - 60 minutes, in the test - 3400 sec/56-57 minutes, measured capacity at 3A - 2840mah).
- Next comes the popular bank Sanyo UR18650FM 2600mah 4.2V (8.65Wh, the voltage holds a little worse than the Ski, but there is a high threshold of 4.35V, for 4.2V batteries it’s just fine, the capacity is 2600mah, i.e. in theory it should hold 3A - 51.6 minutes, in the test - 2960 sec/49.5 minutes, measured capacity at 3A - 2473mah As you can see, a little less than stated, but the parameters are simply excellent).
Next is our Panasonic NCR18650PF 2900mah 4.2V (8.89Wh, the voltage holds perfectly, at first it even surpasses the Sanyo, the capacity is 2900mah, i.e. in theory it should hold 3A - 58 minutes, in the test - 3054 sec/51 minutes, measured capacity at 3A - 2551mah. As you can see, it is much less than stated, but it has a discharge threshold of up to 2.5V (in the test up to 3V). and Samsonov).
And the latest Samsung ICR18650-26F 2600mah 4.2V (8.73Wh, the voltage holds a little worse than the Sanyo, but the capacity is a little larger, plus it costs mere pennies, the capacity is 2600mah, i.e. in theory it should hold 3A - 51.6 minutes, in the test - 3036 sec/50.6 minutes, measured capacity at 3A - 2538mah As you can see, Sanyo is better, and when compared with Pornoslonik 2900mah).
Here is a comparison in another comparator between Sanyo and Samsung (unfortunately, our Panos is not in it):

A little information about the production date of Sanyo cans:
According to the official datasheet:


My jar was marked UR18650FM S15B, i.e.:
- UR18650FM – let it be the model name
- the first letter is the year of manufacture: A – 1996, B – 1997…. O – 2010, P – 2011, Q – 2012, R – 2013, S – 2014, T – 2015, etc.
- the next two digits indicate the week the can was released: week 15 - mid-April
- the third letter is the technological line.
Total: Sanyo UR18650FM S15B production date - April 2014.

A little information about the production date of Panasonic cans
My jar was labeled NCR18650PF 4307 (bottom line, four characters), i.e.:
- NCR18650PF – let it be the model name
- the first digit is the year of manufacture: 1 – 2011, 2 – 2012, 3 – 2013, 4 – 2014, 5 – 2015, etc.
- the next digit is the month of issue: 1 – January, 2 – February, 9 – September…… X – October, Y – November, Z – December
- the third and fourth digits are the day of the month: 05, 14, 29.
I don't know what the capital letter means. Maybe either a technological line, or a quality class, or a place of production. In general, I don’t know, but it’s interesting.
Total: production date of Panasonic NCR18650PF 4307 – March 7, 2014.

A little information about the production date of Samsung cans:
Old datasheet:


For example, marking SAMSUNG ICR18650-26F 2CB3 (bottom line, four characters), i.e.:
- ICR18650-26F – let it be the model name (according to the “standard”)
- the first digit is the branch of the company where the battery was manufactured (not interesting)
- the second digit is the year of manufacture: Y-2005, L-2006, P-2007, Q-2008, S-2009, Z-2010, B-2011, C-2012, D-2013, E-2014, F- 2015, G-2016, H-2017, etc.
- the third digit is the month of issue: 1 – January, 2 – February, 9 – September…… A – October, B – November, C – December
- the fourth digit is the week the can was produced: 1, 2, 3, 4 and 5
Total: production date of SAMSUNG ICR18650-26F 2CB3 – 3rd week of November 2012.

A little information about the production date of LG cans
For example, the marking is LG ICR18650D1 3000mAh L040B097A1 (the first four characters are needed), i.e.:
- LG ICR18650D1 – let it be the model name
- the first digit is the year of manufacture: J – 2010, K – 2011, L – 2012, M – 2013, N – 2014, etc.
- the next three digits are the day of issue: 040 (40th day), it’s inconvenient to calculate...
Total: production date of LG ICR18650D1 L040B097A1 – February 9, 2012.

PS, all the information was found on the Internet at different times and recorded in a text file (I always add useful information this way). I don’t remember exactly what resource I found it on, so don’t even ask :)

It is difficult to find an area where there are no devices running on electrical energy. Mobile sources include rechargeable batteries and disposable batteries that power the consumer by converting chemical energy into electrical energy. Lithium-ion batteries are electron pairs with active components containing lithium salts. The shape of the battery resembles a disposable AA battery, but is slightly larger, has hundreds of charging cycles, and belongs to Li-ion 18650 batteries.

Production of lithium-ion batteries is based on company sites Sanyo, Sony, Panasonic, LG Chem, Samsung SDI, Skme, Moli, BAK, Lishen, ATL, HYB. Other companies buy elements, repackage them, passing them off as their own products. They also write false information about the product on the shrink film. There are currently no 18650 Li-ion batteries with a capacity higher than 3600 mAh.

The main difference between rechargeable batteries and batteries is the possibility of repeated recharging. All batteries are designed for a voltage of 1.5 V, the product has a li-ion output of 3.7 V. Form factor 18650 means a lithium battery 65 mm long, 18 mm in diameter.

18650 lithium battery operating mode characteristics:

• The maximum voltage is 4.2 V, and even minor overcharging significantly reduces the service life.
• The minimum voltage is 2.75 V. When reaching 2.5 V, special conditions for capacity restoration are required. When the voltage at the terminals is 2.0 V, the charge is not restored.
• The minimum operating temperature is -20 0 C. Charging at sub-zero temperatures is not possible.
• Maximum temperature +60 0 C. At higher temperatures, an explosion or fire can be expected.
• Capacity is measured in Amps/Hours. A fully charged 1Ah battery can supply 1A of current for an hour, 2A for 30 minutes, or 15A for 4 minutes.

Charge controller for li-ion battery 18650

Major manufacturers produce standard 18650 lithium batteries without a protective board. This controller, made in the form of an electronic circuit, is installed on top of the case, lengthening it somewhat. The board is located in front of the negative terminal and protects the battery from short circuit, overcharging, and overdischarging. Defense is being assembled in China. There are devices of good quality, but there are outright scams - unreliable information, capacity 9,000A/h. After installing the protection, the case is placed in shrink film with inscriptions. Due to the additional design, the case becomes longer and thicker, and may not fit into the intended slot. Its standard size can be 18700, and can be increased due to additional actions. If the 18650 battery is used to create a 12V battery that has a common charge controller, breakers on the individual Li-ion cells are not needed.

The purpose of protection is to ensure the operation of the energy source within the specified parameters. When charging with a simple charger, the protection will not allow overcharging and will turn off the power in time if the 18650 lithium battery runs down to a voltage of 2.7 V.

Marking of lithium batteries 18650

There are markings on the surface of the battery case. Here you can find complete information about the technical properties. In addition to the manufacturing date, expiration date and manufacturer's brand, the device of 18650 lithium batteries and the consumer qualities associated with this aspect are encrypted.

1. ICR – lithium-cobalt cathode. The battery has a high capacity, but is designed for low current consumption. Used in laptops, video cameras and similar long-lasting equipment with low energy consumption.
2. IMR– lithium-manganese cathode. It has the ability to produce high currents and can withstand discharge up to 2.5 a/h.
3. INR – nickelate cathode. Provides high currents, withstands discharge up to 2.5 V.
4. NCR – Panasonic specific markings. The properties of the battery are identical to the IMR. Nickelates, cobalt salts, and aluminum oxide are used.

Positions 2,3,4 are called “high-current”, they are used for flashlights, binoculars, and cameras.

Lithium ferrophosphate batteries have the ability to operate at deep minus temperatures and are restored during deep discharge. Undervalued on the market.

By the marking you can determine whether this is a rechargeable lithium battery with the letters I R. If there are letters C/M/F, the cathode material is known. The capacity indicated will be mA/h. The release date and expiration date are located in different places.

You should know that manufacturers of rechargeable lithium batteries do not have products with a capacity of more than 3,600 mAh. In order to repair a laptop battery or assemble a new one, you need to purchase batteries without protection. To use a single copy, you need to buy elements with protection.

How to test a 18650 lithium battery

If, when buying an expensive device, you doubt the veracity of the information on the case, there are ways to check. In addition to special meters, you can use improvised means.

• You have a charger, you can time the time of full charging with a certain current strength. The product of time and current will reveal the approximate capacity of the li-ion battery.
• A smart charger will help you. It will show both voltage and capacity, but the device is expensive.
• Connect the flashlight, measure the current, and wait for the light to go out. The product of time and current gives the current capacity in A/h.

You can determine the power of a battery by weight: a 18650 lithium battery with a capacity of 2000 mAh should weigh 40 g. The higher the capacity, the greater the weight. But the defectors have learned to add sand to the body to make it heavier.

Charger for 18650 lithium batteries

Lithium batteries are demanding on terminal voltage parameters. The maximum voltage is 4.2 V, the minimum is 2.7 V. Therefore, the charger works as a voltage stabilizer, creating 5 V at the output.

The determining indicators are the charging current and the number of elements in the battery, which you set yourself. Each element (jar) must receive a full charge. Power is distributed using a balancer circuit for 18650 lithium batteries. The balancer can be built-in or manually controlled. Good memory is expensive. Anyone who understands electrical circuits and knows how to solder can make a charger for li-ion with their own hands.

The proposed do-it-yourself charger circuit for 18650 lithium batteries is simple and will turn off the consumer after charging on its own. The cost of components is about 4 dollars, not a shortage. The device is reliable, will not overheat and will not catch fire.

Charger circuit for lithium 18650 batteries

In a homemade charger, the current in the circuit is regulated by resistor R4. The resistance is selected so that the initial current depends on the capacity of the 18650 lithium battery. What current should be used to charge a li-ion battery if its capacity is 2,000 mAh? 0.5 - 1.0 C will be 1-2 amperes. This is the charging current.

What current to charge a li-ion battery 18650

There is a procedure for restoring the functionality of a 18650 lithium battery after the voltage drops to operating voltage. We restore capacity measured in amp hours. Therefore, first we connect the Li-ion battery form factor 18650 to the charger, then we set the charging current with our own hands. The voltage changes over time, the initial value is 0.5 V. As a stabilizer, the charger is designed for 5 V. To maintain performance, parameters of 40-80% of the capacity are considered favorable.

The charging scheme for a li-ion 18650 battery involves 2 stages. First, you need to raise the voltage at the poles to 4.2 V, then stabilize the capacitance by gradually reducing the current. The charge is considered complete if the current drops to 5-7 mA when the power is turned off. The entire charging cycle should not exceed 3 hours.

The simplest single-socket Chinese charger for li-ion 18650 batteries is designed for a charging current of 1 A. But you will have to monitor the process yourself, switch it yourself. Universal chargers are expensive, but they have a display and carry out the process independently.

How to properly charge a Li-ion 18650 battery in a laptop? Connecting a set of energy sources in the gadget via Pover Bank. The battery can be charged from the mains, but it is important to turn off the power as soon as the unit has reached capacity.

Restoring li-ion battery 18650

If the battery refuses to work, it may manifest itself as follows:

• The energy source is quickly discharged.
• The battery is dead and won't charge at all.

Any source can quickly discharge if the capacity is lost. This is precisely why overcharge and deep discharge are dangerous, from which protection is provided. But there is no escape from natural aging, when storage in a warehouse annually reduces the capacity of the cans. There are no methods of regeneration, only replacement.

What to do if the battery does not charge after a deep discharge? How to restore li-ion 18650? After the controller disconnects the battery, it still has a reserve of energy capable of delivering 2.8-2.4 V voltage at the poles. But the charger does not recognize a charge up to 3.0V; anything lower is zero. Is it possible to wake up the battery and start the chemical reaction again? What needs to be done to increase the charge of li-ion 18650 to 3.1 -3.3V? You need to use a way to “push” the battery, give it the necessary charge.

Without going into calculations, use the proposed circuit, mounting it with a 62 Ohm resistor (0.5 W). A 5V power supply is used here.

If the resistor heats up, the lithium battery is zero, which means there is a short circuit or the protection module is faulty.

How to restore a 18650 lithium battery using a universal charger? Set the charge current to 10 mA, and perform precharging as written in the instructions for the device. After raising the voltage to 3.1 V, charge in 2 stages according to the SONY scheme.

Which 18650 lithium batteries are better on Ali Express

If the cost and quality of a 18650 lithium battery is important to you, use the AliExpress resource. There are a lot of products here, from different manufacturers. The battery you are looking for is in demand and people like to counterfeit it. Therefore, it is necessary to know the main differences between a good model and a replica.

Be critical of the indicated capacity. Only the best manufacturers have achieved 3,600 A/h, the average ones have an indicator of 3000-3200 A/h. The protected battery is 2-3 mm longer and slightly thicker than the unprotected one. But if you are assembling a battery, protection is not needed, do not overpay.

High-quality products are more expensive here too. Please note that Ultrafire promises 9000 mAh, but in reality it turns out to be 5-10 times lower. It is better to use a product from a trusted manufacturer, and try to always buy the same brand of battery.

We suggest you look at the procedure for restoring a 18650 lithium battery

I’ll say right away that Li-ion (lithium-ion, lithium) batteries size 18650 at 3.7v, like many other things, I buy on AliExpress. Links to them are at the bottom of the article.

Why there? Because on AliExpress has a very large selection and you can buy them at a very affordable price..

But precisely because 18650 batteries are very popular, the Chinese are very fond of counterfeiting them, so it’s not worth rushing for beautiful numbers with an unrealistically large capacity or a low price.

I will talk very briefly about the batteries themselves, give some advice - which batteries are better not to buy, how to use them, and give links to really good 18650 batteries, and which ones are better is up to you to decide, because... and their characteristics and purpose differ, although the average operating voltage is the same for all - 3.7v.

As a rule, 18650 battery size is: diameter - 18-18.3 mm, height - 65 mm (for batteries without protection). Protected batteries have a diameter of about 18.5 mm and a height of up to 70 mm.

A protected battery, unlike an unprotected one, has a board built into it (charge/discharge controller), and it externally has a positive contact like a small (about 1 mm) protruding pin.

This controller protects the battery from overcharging above 4.2v and from discharging below 2.75-3.0V (different batteries have different lower values, you should look at its description (datasheet), because beyond these values ​​the battery will quickly fail.

Which one is better to use? It depends on what you charge it with and where you use it..

As a rule, normal chargers (designed specifically for charging lithium-ion batteries, for example the 18650 type) have a charge controller and do not overcharge these batteries, so any type can be used in them.

PowerBanks have a full charge and discharge controller, so they use batteries without protection, and in some cases protected batteries will not even fit into the PowerBank due to the protruding contact.

But if you use a battery, for example, in a simple Chinese lantern, a children's car or an electronic cigarette, where there is no built-in discharge controller, then you must use a battery with built-in protection, otherwise it will not last long.

By the way, about electronic cigarettes, mechanical mods etc. – it’s better to use them high current 18650 lithium batteries, designed to deliver high currents - up to 40-60 A(short term). Conventional batteries designed for loads of 2-3C (up to 4-5A) will also “die” quickly.

If you use a battery with a step-up voltage converter, then pay attention - at what minimum input voltage does this converter start working? If it’s from 3 volts, then everything is fine, you can use any type, but if, for example, from 2 volts, then the battery without built-in protection will be “sucked out” completely, which “is not good.”

Regarding the capacity of 18650 type batteries: at the time of writing (beginning of 2017), the maximum capacity that I encountered was a maximum of 3400 mAh, and only from well-known manufacturers such as Sanyo, Panasonic, most others, for example LG, Sony, Samsung, etc. - about 3000 mAh, and the price for them is also not the lowest.

Personally, today I prefer already time-tested 2600 mAh batteries from Sanyo and Samsung, which can already be purchased at a very affordable price.

But, On AliExpress you can buy a lot of cheap fakes like Ultrafire, on the cases of which the capacity may be indicated as 3000, 5400, or even 9000 mAh, etc., but the real capacity of which will be 5 or even 10 times lower!

Also, if you have an 18650 battery and have nothing to check its actual capacity, then just weigh it! Batteries with a capacity of 2000 mAh or more must weigh at least 40 grams! And, as a rule, the higher the actual capacity, the more it will weigh.

Although some “leftist” manufacturers have already learned to “bypass” this point. They just add something inside for weight, like regular sand.

That's why, Don’t chase a low price and big numbers on the case, you shouldn’t save on this!

The most reliable thing is to use verified links, but always, without fail, anyway carefully read reviews for a specific battery and then you won’t get into trouble.