Before anything, I’ll briefly explain what 18650 cells are and what uses they may have. I have worked a lot with 18650 cells and I used them for pretty much anything that needs power.
Basically, they are Li-Ion cells, that means they have the same overall parameters as a now-days phone battery. Their nominal voltage is 3.7V or 3.6V, but this is not too relevant. What’s important to note is that they are fully charged at 4.2V and they are considered discharged at 3.3V. Overcharging or excessively discharging them will shorten their lifetime.
The cells can be used for quite a lot of applications: flashlights, lasers, measurement tools, even power tools (but in this case some special ones are used that can provide higher current and have lower capacity – I will not discuss the tech details here). Practically, anything that used to be able to work with 3 AA/R6 or AAA/R3 batteries can be safely used with an 18650 cell. If the space conditions are met, it’s really good to have only one standard type of cell for anything. It’s very useful instead of having various sizes of rechargeable batteries.
Now, to get to the point of the article: there are many dozens of types of 18650 cells that can be found in shops, on-line sites or laptop batteries. I will try to explain here how to find the correct capacity for the biggest 18650 cell manufacturers around. Note that ripping old laptop batteries is a good near-free way to acquire cells. Usually, you will find a dead pair, a good pair and 1-2 intermediary ones (assuming there are 3/4 pairs in the battery). Most of the time the cells that have 2V+ when ripped out can recover most of their capacity when charged, while the ones under 1V are no longer usable and will overheat if you try to charge them.
There are 4 very big companies that produce (used to be) very good quality cells: Samsung, Sanyo, Sony and LG. And there’s also the 99.998% fakes called Ultrafire. Practically, all Ultrafire cells on the online market that state any capacity over 3000mAh are fakes. Since there are other fake cells with fake-stated capacity, I’ll tell you how to detect them too. Fist of all, they have stated capacities of over 4000mAh, which is not currently possible. The best confirmed capacity original cell at this point has 3400mAh. Second, their weight is lighter. Original cells are 45grams+. Fakes have mostly under 40g, and the worst quality ones are even 20g. Those have an effective capacity of under 500mAh, even if they state 4000mAh+ on the label.
Now, for each of the 4 big companies I’ll tell you how to see what actual capacity a cell is. I’ll also post RGB values, since the pictures may not look 100% like the original.
Most Samsung cells in circulation are kind of Cyan color (RGB: 80,255,255). Note that other smaller companies use this color, but only the Samsungs have Samsung written on them.
Here is the color I’m talking about – in this picture we have a 2000mAh cell. Same color can be found for 2200mAh (most common) and 2400mAh.
The 2000mAh ones can also be light blue (RGB: 40,200,255).
Light green (RGB: 15,240,115) is used by Samsung for 2200mAh and 2400mAh cells:
The majority of the 2200mAh cells are Cyan, like the pic with the 2000 ones. The green version is the newer 2200 model.
Most 2400 mAh cells are DarkSkyblue (RGB: 0,120,240):
The 2600 mAh cells from Samsung come in only one color so far – Ugly Pink (RGB: 255,128,255):
Note that it’s more pink/ugly when seen live.
Samsung also has 3000mAh cells on the market, which are not that ugly as the pink ones (RGB: 100,133,200):
Since for 2000,2200 and 2400 mAh cell things can get confusing when it comes to colors, the best way to identify capacity is from the end of the line number in the first text line on the cell (the row where it says 18650). As you can see in the pictures, that’s exactly what 20,22,24,26 and 30 mean – it’s the capacity tag for any Samsung cells. So there you have it, you can now identify any Samsung cell.
Most Sanyo cells are RED (RGB: 255,0,0), or the new fakeRED (RGB: 255,0,64) that’s infested with blue (we’ll talk about that later). They are the most hard to identify overall.
This is how a real red cell suppose to look like (RGB: 255,0,0):
The 2000mAh original ones are indeed red by any standards. The cap is white. So if it’s pure red ones it’s 2000mAh capacity. The newer ones were also fakered (RGB: 255,0,64), but the cap is still white.
Here they are:
The 2200mAh cells and above are fakered (RGB: 255,0,64). It’s hard to detect in a picture, but there’s a clear tendency towards purple for those.
You can tell the cells that have 2200mAh capacity be the RED cap. Yes, the cap is true red, unlike the rest of the cell.
The 2600mAh ones are also fakered (RGB: 255,0,64), but those have cyan cap. Don’t get tricked by the red in the picture, it’s a lot more towards purple in practice:
The new 2800 and 3100 capacity models are orange and purple, but I haven’t seen any yet, so I won’t post them yet.
The high power cells (like the high current 1500mAh ones used in power tools) have a pink or light blue cap.
So, to identify the Sanyo cell, you’ll have to use actual color nuance and cap color, since the series written on them are most of the time barely visible.
Still, I’ll list the known series so you know what’s what if you can actually read it from the cell:
UR18650EA 2350mAh High Drain
UR18650RX 2050mAh High Drain
UR18650W2 1600mAh High Drain
UR18650WX 1600mAh High Drain
UR18650A 2250mAh Standard
UR18650AA 2250mAh Standard
UR18650ZY 2600mAh Standard
UR18650ZT 2700mAh High Capacity
UR18650ZTA 3000mAh High Capacity
They are part of the above, so I did not consider them a separate company.
Panasonic has 3 common cells in circulation.
Sony are standard green (RGB: 0,183,0). All of them are the same green so we’ll have to identify them differently. The way to identify them is the G-number.
On the second line, the first number after the G is the capacity identifier.
Here’s the 2200mAh cell:
Here we have the 2400mAh cell:
And finally the 2600mAh one:
As you can see, the 2000mAh cell is marked with G5, the 2400 one with G7 and the 2600 one with G8.
That’s how to tell them apart. There’s also another important difference for the 2600mAh cell: it’s case does not cover the bottom at all, unlike the 2200 and 2400 ones there it’s bent and covers about 1mm of the bottom part. I think 2400mAh cells do exist that have no bottom cover also, but are in significantly smaller number.
Last one in the big league is LG. In their case, the series on the cells are a big mess and will never make sense unless you search for them and even then you may not find anything relevant. But the good thing is that they can be identified very easy by color.
The 2000mAh cells are pale orange (RGB: 255,155,112); they can still be found around:
As you see, the good way to identify LG cells is directly by color.
So there you have it – each one has a trick: for Samsung you have to check the tag at the end of the line, for Sanyo the cap for Sony the G-spot and for LG just the cell color.
If you have any unidentified cell, don’t hesitate to post a link with a picture of it and I’m sure we can find what’s with it.