For anyone that might stumble on this thread because they are searching for high capacity 18650 cells…

At the time of this post, the maximum legitimate capacity for an 18650 cell is 3500mAh.

High quality, reliable cells with this capacity are available from manufacturers like Molicel and Samsung. It is important to consider that capacity is affected by discharge rate and the A (discharge current) rating of a cell must be considered along with the mAh (capacity) rating to determine the best cell for your application.

Increased capacity and discharge current mean increased cost, and you can save some money if you buy cells with reduced discharge current ratings if your focus is battery life and your application doesn’t require maximum current. For example if you are rebuilding a pack for a cordless drill, you might want to choose the more expensive, high current options—but if you are building a pack to run a microcontroller for a long time at low power, you can save money by not choosing something you will never actually use.

Examples of top-end cells are listed in the table below. These are meant to be exemplars only, there are other brands with good reputations—though Molicel and Samsung are common safe bets.

Manufacturer	Model	Style	Capacity (mAh)	Discharge (A)	Price (USD)¹
Molicel	M35A	FT, NP	3500	10	7.99
Molicel	M35A	BT, P	3500	10	9.99
Samsung	35E	FT, NP	3500	8	7.99
Samsung	35E	BT, P	3500	8	9.99
Samsung	35E	BT, NP	3500	8	9.99
Samsung	30Q	BT, NP	3000	15	7.99

1. Street price from a reputable dealer at the time of this post.

STYLE KEY

FT	Flat Top—suitable for building batteries
BT	Button Top—for devices with replaceable cells²
P	Protected—includes protection circuitry
NP	Not Protected—does not include protection circuitry

2. Please note that a button top is no guarantee of protection being present as in the Samsung 35E and 30Q. Such cells should not be used in devices that don’t have their own over-voltage, under-voltage, and over-current protection for the cells—this is a potentially dangerous thing to do and a fire hazard which may not show up until you attempt to charge the cell.

 

I know they do not have 9900mAh capacity. I used to order such items and used to open disputes with test videos. So I used to get a partial refund and the final cost was too cheap.

I'm actually trying to find some batteries that offer close to the advertised capacity. Now, I send messages before I buy about capacity verification and no-return 100% refunds for batteries that don't actually have much capacity.

The 9900mAh battery I tested had 125mAh capacity. Unfortunately, I didn't know at the time that I needed to test capacity and didn't ask for a refund. I did buy some 18500 1600mAh at the same time that turned out to be accurate (1.59-1.66Ah for the 3 I tested).

The 88800mAh 18650's would have made great 2Ah batteries.

I've been asking for, and getting, 100% no-return refunds. I have no patience or sympathy for sellers who are selling batteries with less than 10% of the advertised capacities. I bought some "real capacity" 2.5Ah 18650's that had about 2Ah of capacity and I'm letting the seller get away with that.

I have some 1.2-2.8Ah 16340's that a member gave me. They test at 5-50mAh. He used them to power a homemade experimenter. I'm looking for some 16340's that would make the experimenter "work". In the meantime, I added a power jack so I can use an adapter for power.

I ended up buying a capacity tester for the last two sets of batteries I purchased because the method I initially used isn't as accurate and I adjusted the discharge current to discharge the batteries in an hour (once I determined the ballpark for the actual capacity). I used one of the cameras from my surveillance system to record battery voltage because it puts the time in the upper left corner. But it breaks up the video every hour; and I didn't want to have to upload videos as evidence that were larger than a few hundred MB.

 

didn't want to have to upload videos as evidence that were larger than a few hundred MB.

There was a limit on file size and I kept having to convert images from png to jpeg or gif and in some cases edit the image in order to upload them below their limit. Not sure if an hour long mov file would fit within their limits. Can't find any info online. It just pops up as an error when trying to upload to their report software function.

 

There was a limit on file size and I kept having to convert images from png to jpeg or gif and in some cases edit the image in order to upload them below their limit. Not sure if an hour long mov file would fit within their limits. Can't find any info online. It just pops up as an error when trying to upload to their report software function.

I think their limit is in the GB range for videos, but I have slow DSL. My surveillance videos are .mp4 with decent compression. An hour is under 300MB.

The problem for me is that I could never upload videos to the AliExpress website. After complaining many times in the midst of a dispute, they said I could upload to YouTube and post the URL. YouTube was much more accommodating of my extremely slow (<1Mpbs) upload speed.

 

They've mentioned movies to me but I have no desire to do so. Pics are a pain in the ass enough for my lack of patience and I fought them hard about them needing one before I sent the first one to them. FWIW

 

Flipping through news articles and this little ad popped up...

Now even with the $230 delivery that doesn't sound too bad for a sit-down auto-balancing powered unicycle. See that little "Color: wheelbarrow" near the bottom of the ad? Here is what you are actually buying...

The real deal is...

Caveat Emptor!