18650 questions

Hello - I am a new member with my first post. I will confess up front that I do not know much about electricity. Recently I purchased a couple of Olight flashlights that use the 18650 battery. While perusing the Olight web site I noticed something that raised a question. I saw multiple 18650 batteries having different mAh ratings. My understanding is all 18650 batteries are the same size physically so are these batteries having different mAh ratings interchangeable? Are more mAh better?

The other question has to do with charging these batteries. When I recieved the lights I connected the magnetic chargers to a USB port on my computer and that worked fine. My question is can I use an adapter that accepts a USB connection (Olight charger) and plugs into a standard wall socket? Will this charge the battery faster? Will it damage the battery?

Sorry for the basic questions and thanks in advance for any input.


These are all good questions!

Most 18650 batteries are interchangeable because they have the same voltage (3.7V nominal, with a maximum of 4.2V).
However, Olight often uses proprietary batteries for their lights, meaning the light may not work (partially, or at all) with other 18650 batteries. (It’s not the most consumer-friendly.)
You’ll have to do some more research on the specific models you bought to see how much flexibility you have.

Additionally, more mAh is often better…but high-capacity batteries tend to have lower maximum current.
This matters for very bright lights that demand a lot of energy at once, like the Lumintop FW3A.
For lights that put out about 1000 lumens or less, this isn’t as important and you can generally put whatever you want in them.

Your Olight chargers would do fine on a wall adapter, as it’d still give the 5V that that charger expects.
You may see some speed improvement, since computer USB ports can only put out so much current - but it depends on the wall adapter.
Take a look at the adapter’s maximum current (they usually have it written on the bottom/side), and if it’s quite low (1A or less), you might not notice the difference.

For 18650 a couple of things. More mAh isnt always better, and you dont always need high discharge rates. Basically you need to match up your led/driver setup with the right battery specification. Olight does a great job of that with the cells they include with the light you buy-they’re matched up really well for the led/driver.

The general rule of thumb is this: high performance leds behind fet drivers need higher drain cells like a fw3A or Kr4 that pull 15 or 20 amps on turbo. Something like a 7135-based driver at 2.8 amps doesn’t need a high drain cell. Also, The higher the current carrying capability of the 18650, the lower the capacity will be. The highest capacity, highest drain cell currently is the Sanyo 18650GA or the Samsung 35E.

Olight recommends using a charger with at least 2.4 amps output for optimum performance of the MCC3 charging system.

Hey hcaroselli, Welcome to BLF

I will try to explain a bit about batteries and specifically about 18650.

1. The name (or number) 18650 is represent the size and shape of the cell the first 2 digits means that the diameter of the cell is 18 mm, the next 2 digits means the length of the cell is 65 mm and last zero means it is a round cell. Another example is 21700 cells - a round cell with 21 mm diameter and 70 cm length.

2. Since the number is only represents the shape, 18650 cells can be of different technologies such as LiFePO4 or LiCoO2 it means that 2 different 18650 cells that looks the same may have different properties such as capacity, maximum current and even voltage and it is important to know what type of cell you have in order to properly charge it.

3. the basic 18650 cell is non protected, it means the cell has no electronics inside and the user can charge or discharge it as he want. the problem is Lithium cells are not meant to be charged above their max voltage (usually 4.1 or 4.2V but not always) and not to be discharge below the minimum voltage (around 3.5v). Because of these limitations, some cells have a built-in protection circuit and will be a bit longer since the circuit is about 2-3 mm thick but they are just called protected 18650 (and not "18670" or so).
the protected cells are "safer" since they are protected against over charge, over discharge, short circuit etc. But the problem they can't provide high currents and are not good for turbo mode that requires high current.
In addition the driver inside the light has a over discharge protection and the charger or the charging circuit in the light have a over charge protection so non-protected cells are not so dangerous as one might think.

4. Another type of 18650 is button top and it have a metal button on the positive terminal (the same as Alkaline cells have) some lights will only work with that type of cells

5. A rare type of 18650 comes with a USB socket and a built-in charger.

That is all I can think of right now :)

PS: maximum capacity of 18650 cell is 3500mAh so anything above this number is a fake (many fake cells are out there so buy only from known sellers)

ALL great answers above :+1: :+1: :+1:

I wish I had stumbled across a post like this when I was getting started!

You got some last minute advice there that I’ll second… there are lots of counterfeit 18650s and MOST come from China and are typically separate from the light purchased (unless a better brand like Olight for sure). There are two reasons for concern there:

1) Ratings are usually overstated from reality on a lot of batteries out of China (including eBay too BTW). Yes, there are a FEW good batteries coming out of China, but a LARGE majority are going to not meet specifications and a “rewraps” come from lesser quality makers OR are rejects from the larger makers (sold off in bulk and then resold through places like AliExpress, etc.)

2) Some of these “rewraps” can be dangerous. Stick with major brands like: Samsung, Sony, LG, Molicel, Panasonic and you’ll be fine. Remember… these are considered OEM products and so there is no UL or CE listing on these batteries. YOU have to be the safety guy!

There are several great battery sellers in the US so I’d say start with my personal favorite (18650battery.com) where you can LEARN about capacity Vs. current output (ability) by just looking over their inventory. They are honest, sell authentic only, and give the stats for each battery at a realistic level.

If you decide you want a certain battery, you can also search it here at BLF and look up reviews (from cool dudes like HJK who reviews HUNDREDS of batteries here).

Welcome to you next bad habit :stuck_out_tongue:

Thank you all for this great feedback. I will reread it and see how much I can digest. Forgot to mention a couple things. I am 75 years old and reminded of the old dog new tricks story.

There is another thing I did not mention and I have a little more information now.

The 18650 batteries that were causing my confusion are both Olight brand batteries which I understand are proprietary. At this moment I am staring at both of them; both Olight brand and both 18650 batteries. One is specified as 3200 mAh and one is 3500 mAh and this is what was causing my confusion. For what it’s worth the 3200 mAh Olight battery came in the Olight S2R Baton II and the 3500 mAh Olight battery came in the Olight Baton Pro. These are new lights received in the last few days.

Is the 3500 mAh battery simply an update? Can I use it in the S2R Baton II without damage?

Thanks again for the great info.


You should be able to use the batteries interchangeably, but the performance might be different. The Baton Pro is brighter so the led is probably driven harder and/or different than the Baton II.