18650 Battery size-dimensions. What do all these numbers really mean? Wild, wild world of Lithium-ion batteries

The Answer:

18 - The first two digits "18" stand for li-ion battery diameter in millimeters. In this case width of the battery is 18mm (millimeters).
65 - The third, and fourth digit stand for length in millimeters. That would be 65mm.

0 ? -  For those who want to know why zero is there, this is how battery manufacturers calculate batt. length: 650 divided by 10 is 65mm.  Since we are simple people we will forget about zero for now.

18650 battery size dimensions
18mm by 65mm - 18650

Metric system (millimeters) is used almost always when we see li-ion battery with numbers like:
Above are the most common li-ion battery sizes. So, next time when you see 18650 battery you will know for sure meaning of all these numbers.

Let's see what we have learned today.

What is 26650?

26mm - diameter
65mm - length

Battery dimensions in a real world can, and will vary.
These measurements are for bare Li-ion cells only (also called "unprotected" or "flat top").
If you see "PROTECTED" printed next to 18650, 16340, 14500, 26650 ...  that means that external protection circuit board is welded to the bottom of the bare cell, and flat wire is added to the side of the cell.
Because of added external protection protected Li-ion batteries are 2.5mm to 3mm longer, and can be 0.5mm wider than bare Li-ion cells.
I will explain what Protected Li-ion battery is in one of my next posts.

By the way, 16340 rechargeable li-ion battery is also called RCR123. It is the same size as CR123A primary (non-rechargeable) cell. First letter "R" means rechargeable.
And again, if word "Protected" is printed next to 16340 (or RCR123), battery will be longer than regular CR123A by 2.5mm to 3mm.
14500 Li-ion is the same size as AA battery, but it should never be used as a replacement for regular (Ni-Mh) AA battery. Why? Well, stay tuned I will keep posting some interesting stuff.

As you can see from this photo battery size will vary slightly. This is one bare unprotected 18650 battery. Flat top.
Protected 18650 (or any 26650, 16340, 16650,14500 ...) lithium-ion batteries will be approximately 2.5-3 mm longer, and 0.5 mm-0.6 mm wider in diameter.


LG HG2 Battery Review 18650 Test 20A 3000mAh Part 1

Let's start with LG HG2 battery review - performance test.

LG 18650HG2 18650 battery li-ion (lithium-ion) is made and distributed by well-known LG Chem manufacturer located in South Korea.
LG Chem is also known as LG Chemical, the largest chemical company in S. Korea.
Quick Fact:The Ford Focus Electric, Volvo V60 & Chevrolet Volt are powered by LG batteries.

Basic info

  • Model: INR18650HG2
  • Capacity: 3000mAh
  • Released: 2014
  • Product Classification: Cylindrical rechargeable lithium ion battery
  • Intended use (application): Power Tools
  • Max. Constant Current 20 A (20000 mA)
  • Cycle Life @ 10A: 300 cycles at 10 A
  • Cycle Life @ 20A: 200 cycles at 20 A
  • Initial AC impedance: less (or equal) than 20 mΩ
  • Dimensions: Diameter Max 18.5mm, Height Max 65.2mm
  • Weight: Max 47g
  • Operating temperature (battery cell surface temp.): -20 ~ 75 ℃
  • Lower limit (cutoff) discharge voltage under load: 2.5V
Yes, that is correct this cell is made for Power Tools.
Unprotected 18650 batteries are not intended to be used in vape mod (e-cig) devices, or flashlights.
That is because each 18650 battery (or battery pack) should have properly designed and installed electronic protection circuit (per manufacturer recommendation). Incidentally, LG HG2 became one of the most popular 18650 vape battery cell. That is one of the reasons I picked this particular battery for this review & test.
lg hg2 18650 battery high drain 20A
LG HG2 18650

Manufacturer datasheet 

For this testing, I will use lab calibrated CBA IV Pro Battery Tester - Computerized Battery Analyzer. 
Calibrated and tested to accuracy levels of < 1% Amp load, < 0.5% volts

Review-Test 1 : Capacity @ 15A Continuous Discharge INR18650HG2

Voltage vs Capacity: Let's see how much capacity we can get from LG HG2 under 15 Amp constant (continuous) discharge load. The test battery is fully charged to 4.2V, and discharged to 2.5V. Click on the picture below to see full-size battery discharge graph with the (green) capacity curve.
lg hg2 18650 battery review test 15A capacity curve

15A continuous discharge is somewhere in between two max. discharge values provided by manufacturer-LG for this 18650 li-ion battery cell. 
10A for approximately 300 cycles, and 20A for approximately 200 cycles.
LG HG2 total capacity under 15A is 2835mAh which is very good for this type of battery under 15 Amp continuous discharge rate. 

Voltage drop/sag
LG HG2 test 18650 review voltage drop

The green line in the graph above visually represents what is happening with the battery voltage once power button on your device is pressed.
It is called Voltage Drop.
Voltage drop value greatly depends on:

  • Discharge Load. For this part of the test, it is: 15A Continuous high current drain
  • Internal battery resistance 

18650 Li-ion batteries (all lithium based batteries) have different internal resistance values. Internal resistance depends on build quality (quality control), design (internal, and external), chemistry modifications, a number of cycles, and age of battery cell.

Review-Test 1 : Time vs. Battery Voltage @ 15A Continuous Discharge INR18650HG2

This is the interactive chart. Hover mouse pointer over green line to see it in action.

Discharged from 4.19V to 2.5V @ 15A continuous load in 11 min. and 28 sec.

Review-Test 2 : Capacity @ 20A Continuous Discharge INR18650HG2

LG HG2 Amp limit (according to official manufacturer datasheet) is 20A Continuous current load.
Let's see how this high drain battery can handle 20 Amp

Click on the picture below to expand discharge graph with the capacity curve:
lg hg2 18650 battery review test 3000mAh 20A high drain brown
20 Amp continuous discharge graph

This battery can handle 20 Amp of continuous discharge without problems, but the question is: should you use LG INR18650HG2 @ 20A?
In my opinion, you should not run it at 20 Amp too often.
Why you should not run 18650 battery at full (max) amp load (limit)?
If you read manufacturer datasheet carefully you will see that discharging this li-ion 18650 battery with the very high load will drastically reduce the total number of charge/discharge cycles (lifespan).

Is it good for LED Flashlight?

Luckily LED Flashlights (even high-power 2016 models) do not require such a high current to work at the full power level (e.g. turbo mode).
I will test this (officially rated by LG) 3000mAh battery at lower currents (more suitable for flashlights) just to see how it behaves (voltage drop should not be as deep as @ 20A, and 15A discharge) under lower currents. I think we will be able to get more usable capacity out of it at lower loads. Scroll down to see the test at 5A load.

Is it good for vape mod (electronic cigarette)?

Some new, and inexperienced battery testers are trying to rate li-ion batteries for vape mod users based on continuous discharge tests, and temperature only.
This is definitely the wrong way to test, and recommend (not recommend) batteries for vaping devices.
Lack of experience and basic knowledge about li-ion technology is the biggest problem in the vaping community.

When we want to test 18650 li-ion battery for vape devices - pulse test is the only way to do it. Pulse discharge test is very close to what is really happening with battery cell when it is inside your box mod, or any e-cig device (mech mod, etc.).
I will perform pulse (burst) tests as well, stay tuned.

Using only battery temperature level to rate li-ion battery for vape mods is wrong and provides false (inaccurate) ratings:

  •  Battery temperature level during continuous discharge process is completely different from pulse discharging temperature. 
  • Measuring temperature and rating li-ion battery based on continuous current discharge have nothing to do with vapers. Or in simple words: it gives you wrong information about (real) battery capabilities.
 If battery tester provides ratings based only on temperature then always ask for full temperature graph to be revealed (alongside discharge curve).
Because, a temperature of that battery after 0.5 to 2 minutes under high current load, is much lower than temperature after 4 to 5 minutes under that same high current load.

Advice for vapers:
If you see battery tests ratings based on temperature, and temperature graph (curve showing temperature progress) is hidden, then something is wrong with that test data.
Always ask: Why temperature graph is hidden?
I will provide more tests with temperature data included. These are just basic continuous discharge tests - to see how this cell can handle various constant current loads. So far so good.

Review-Test 3 : Capacity @ 5A Continuous Discharge INR18650-HG2

Let's continue with LG HG2 review. This part of the test will be dedicated to continuous discharge at 5A (5000mA) constant current. From fully charged 18650 battery (full charge = 4.2V)] to the lowest voltage level we can go with this particular li-ion cell -  which is 2.5V.
Click on discharge graph below to expand image - full size.
capacity curve
5 Amp constant current load test discharge capacity graph

Review-Test 4 : Battery Temperature @ 10A Continuous Discharge LG 18650HG2

This is very interesting, and useful interactive chart - hover your mouse over red line (temperature), or blue line (voltage), and you will be able to see:

  • Battery temperature - red
  • Battery Voltage - blue
  • Time (in seconds)
  • Current load is 10A constant value

There is no 18650 30A 3000mAh battery in existence
There is no 35A or 40A 2100mAh or 2600mAh 18650 battery in existence
There is no 20A 3100mAh or 3200mAh or 3500mAh 18650 battery in existence

Safety is the only reason I am doing this.
Li-ion battery can be very dangerous when fake rating and bad seller/tester meet together.

To be continued...

Which is the best 18650 rechargeable battery for flashlight? Samsung 25R 2500mAh, LG HG2 3000mAh, or Orbtronic ORB3400 (Flashlight use)

How to choose the best 18650 rechargeable battery for flashlight?
Which one last the longest?
It is one great question for outdoor enthusiasts ( AKA flashaholics)

I always find reviews and tests from folks who are new to 18650 batteries genuine, and most entertaining.
Average flashlight user doesn't know battery test tricks, and will usually show us a real life 18650 battery performance. Which is very good to get real review data.
They simply charge those cells fully, run them all in the same flashlight (that is important part of this review)...
Lithium-ion rechargeable battery that provides the longest run time is the winner.
Simple as that.
This video shows which li-ion fully charged battery will run the longest in LED flashlight.

Samsung 25R green (very popular battery in vaping and flashlight community)
LG HG2 (good high drain cell, but not any info on flashlight real life usage)
or Orbtronic ORB3400 (well-known battery made for flashlights only)


No-go for Samsung's Batteries in Tesla's Li-ion Battery Packs?

Interesting (and contradictory) things are happening right now on relation Tesla Motors - Samsung-LG-Panasonic.
It seems that Panasonic batteries are, and will be Tesla's exclusive li-ion battery cell supplier.

You can read very good article about latest development here:
Elon Musk confirms that Samsung’s battery cells will not be used in Tesla vehicles, Panasonic gets exclusivity


18650 battery manufacturer Panasonic can speed up Tesla plant investment if needed

As many of you already know Panasonic is one of the main suppliers for Tesla's 18650 battery pack (Model S).
Very interesting news is that Panasonic is ready to do anything to speed up Tesla's "Gigafactory" project.
Tesla will implement existing, and already well developed Panasonic's 18650 battery manufacturing technology.
Gigafactory (located in Nevada) will be the first lithium-ion manufacturing plant of this size in USA.


BMW Adds New Range-Boosting Li-ion Battery Option to i3

Lithium-ion battery technology is very popular among electric automakers. One of the biggest brands that is currently using Li-ion cells to improve mileage is German BMW.
It seems that this time Samsung SDI battery manufacturer is BMW's nr.1 choice.

BMW Adds New Range-Boosting Battery Option to i3

Would you switch to li-ion powered car if prices get more affordable for general population (us)?
What is your favorite electric car?


18650 Battery Review-Vape & Flashlight communities need some real battery tests.

18650 battery test-reviews is what I will start doing from the next week.
It will ne very interesting to see how 18650 batteries behave under different working conditions.
These bench tests and reviews will include:
  • Visual discharge graph (curve) at various continuous and pulse current loads.
  • Battery Amp limit.
  • Real capacity (cell will be discharged from full charge to the lowest voltage discharge cutoff limit).
  • Working temperatures during discharge in real time.
  • Original Battery Specs - datasheet from manufacturers.

You will be able to see the actual performance of the battery cell (in various situations), that you might be using already or that you would like to buy somewhere online but not sure about performance.

Why am I doing this?
Answer: Safety!
It is getting out of control.
Flashlight community is pretty much safe, because 99.9% of today's LED flashlights are running on 18650 Protected batteries.

One, and only independent battery tester is HKJ. You can trust his extensive Li-ion testing 100%.
The lithium-ion safety risk is the highest in vape (electronic cigarette) community that is growing very fast.

Lack of proper li-ion 26650,18650 battery knowledge is the biggest enemy for average vape (ecig) end user (vaper).

To make this already dangerous situation for vaping users even more risky we can see more, and more companies (usually Chinese) releasing unprotected vape 18650, and 26650 batteries with exaggerated Amp limit rating numbers. Sometimes 500% over actual battery Amp rating.
It seems that box mod e-cig batteries are becoming good source of income for individuals who represent themselves as "independent" battery testers.

I will talk more about these "unbiased" battery tests too, and what tricks they use to make battery performance bad, or good.

Just some of the 18650 batteries that will be tested with very accurate (lab calibrated) computer battery analyzer:
LG HE2 and HE4
LG HD2 and HD2C
Samsung 30Q , 25R, 20R
Sony VTC4
Sony VTC5, VTC5A
Sony VTC6
Panasonic NCR18650GA, NCR18650B, NCR18650PF, UR18650NSX

Some very good, and some really really bad, and dangerous rewraps will be tested as well.
Many more batteries will be tested and posted on this blog. This is just a beginning...



How much storage does Tesla expect to sell in 2016?

How much storage does Tesla expect to sell in 2016?: Tesla could sell 168.5 megawatt-hours of energy storage systems to SolarCity this year – 6 times what Tesla sold to SolarCity in 2015.

Tesla, Panasonic, LG Chem, Reposit win ACT battery storage auction

Tesla, Panasonic, LG Chem, Reposit win ACT battery storage auction: First stage of ACT “next generation solar” auction will see 200 Canberra households install a range of battery storage products at a significant discount.


Panasonic NCR18650B 3400mah Amp Limit & 18650 Battery Datasheet

What is Panasonic NCR18650B amp limit, and where I can see original manufacturer datasheet to confirm exact maximum current draw?

Many people from vape, and flashlight community ask this very same question, searching for one simple (and correct) answer.
Continue reading, and you will finally see 100% correct data for NCR18650B 3400mAh Panasonic 18650 Li-ion battery:
18650 Panasonic 3400mah NCR18650B specifications datasheet
Maximum amp limit current draw is 2 C. It is called 18650 battery C rating.  I will explain C ratings in details later.
Right now in plain English, all you need to know when you see "C", and number before "C" :
Multiply the number printed just before letter C by battery capacity.
Where can I find typical rated capacity for NCR18650B?

If you read carefully this PDF document from Panasonic, you will see that typical capacity is  3350mAh, and 2 C (bottom right - battery discharge characteristics graph).

2 x 3350 = 6700mA
In Amps (Ampere) :  6.7 Amp  - much easier number to read.

Maximum NCR18650B discharge amp limit is 6.7 Amps under continuous current load.

There are many high quality 18650 batteries on the market right now.
Panasonic is leader in manufacturing lithium-ion rechargeable cells with unbelievably good quality control.


What does "18650" printed on Li-ion battery stands for?

Now when you have your new LED flashlight, you start looking for the best li-ion batteries money can buy. Searching the internet will not reveal what 18650 stand for. Everything is so confusing, and all those numbers: 18650, 16340, 18500? Thousands of batteries to buy online- the question is: will they fit my new flashlight?
Is this the right battery for me? Will this type of li-ion battery work in my flashlight at all?...
Do you know what all those numbers actually mean?
I will start with 18650 Li-ion battery
Why manufacturers use number 18650? No, these numbers have nothing to do with battery chemistry.
These numbers, printed on li-ion rechargeable battery cells are so easy to forget if you don't know what their meaning is. Numbers, and abbreviations printed on rechargeable li-ion batteries are not that complicated after all. I will explain it in my next post.


The best 18650 Battery in the World? - Panasonic 18650 3400mAh NCR18650B Li-ion

NCR18650B - Weird combination of letters, and numbers that altogether represent one of the most powerful lithium-ion rechargeable 18650 batteries in this present world.  The unbelievably amazing capacity of 3400mAh ( 3.4Ah ) sounds unreal today, but Panasonic specs datasheet is very real, and serious. Imagine millions of ions, jam-packed in one small 18mm by 65mm tube (approx. 1/2 size of permanent marker). But, if you have available: Li(NiMnCo)O2 - magic chemical formula, and the latest battery manufacturing technology then incredible things actually can happen.

NCR18650B Panasonic 18650 battery approximate weight is only 47 grams and that is roughly 1.66 ounces.