How to Know a Fake 18650 Battery
Intro: How to Know a Fake 18650 Battery
An average genuine 18650 batteries will weigh about 45g and no nothing less than 42g. You can see I have a fake 18650 battery in the pic weigh 32g only and the genuine 18650 battery weight 45g. Some genuine 18650 battery can weigh more than 50g. Good brands will tell you the weight of the battery.
You can use a digital kitchen scale.
Why fake 18650 battery weigh less?
That is because inside is a smaller battery with step up circuit which wrap in layers of paper and stuffed inside a 18650 battery size case then heat shrink in a tight plastic label sheet to make it look real.
Genuine sellers will specify battery weight in their product description/sheet.
34 Comments
frer 8 months ago
I have a similar experience with my e-kickbike's battery, the seller on Alibaba stated it was an ekickbike with 21ah battery but when i charged it to full it was only 15.5ah. Seller denies the problem and Alibaba's complaint mitigator denied it too.
englishrupe01 7 months ago
frer 8 months ago
I have a question about how battery Ah is calculated. If a battery pack for ekickbike (mine mentioned above) is stated to be 48v 21ah (48x21= 1.008 kwh) does this mean that if only 0.74kwh (equates about 15.5ah) is used to charge it from "empty" to full it can still be a stated to be a 21ah battery because it maybe has a "hidden" or unaivailable charge below cut off voltage which together with the charge above cut off voltage becomes 21ah (i don't think though there 25% of battery left below 39v because the ekickbike could barely move last 100 metres)?
golowtec 3 years ago
Big Texun 3 years ago
There are a lot of different capacity cells sold, and each weigh a different amount. There are a lot of reasons for using smaller cell sizes, ranging from reducing the cost of the cell for marketing or cost reasons, to safety regulations for a particular regulated application. There are safety standards for appliances used in critical or hazardous environments that might limit how much lithium is present, or have containment requirements that reduce how much you can put in a cell and still meet the safety spec. A cell that is integrated as a backup of short duration might be made for one application, and find it's way to the surplus market where it is sold on ebay... Nothing fake going on there, as long as no lies are being told.
If the battery has a rating that matches it's actual capacity, any capacity or weight is valid. That is a big IF as exaggerations and rip-offs are common. Anyone can cut the shrink wrap off a cell, and replace it with a new wrap, with whatever markings they want. These repackaged cells can simply be remarketed cells, or actual forgeries of popular brands. Some flashlight makers rebrand all batteries they sell. Some are honest and some are not.
And besides capacity specifications, there are safety features, and the absence or presence of cell protection circuitry that has an impact as well.
When evaluating a cell from a new vendor, you should perform a capacity test where you drain a cell to the rated cutoff voltage, then test the charge cycle to see how much charge it takes, then perform a discharge at both slow and fast rates to see the results from thos tests. Discharge rates matter! The slower you discharge a storage cell, the more power in total you get from it. And that affects the cell rating for a given application. So the same cell can have a different capacity depending on what it is used for.
And a sand filled cell sounds fishy, and probably is... Unless there are weight requirements that need to be met coupled with a lower capacity requirement. The buyer of a manufacturer's production run is responsible for the specifications of that run, and their reasons and final product markings could be honest or dishonest. While I would agree in principle that dishonestly market batteries are somewhat fake in nature, the word fake is not an accurate word in most cases. A buyer will always do capacity spot checks as part of the qa of the incoming parts, as most parts have a certain percentage of bad units, and for a product build there will need to be some way to accommodate for the occasional bad part, especially from a new manufacturer or from a surplus supplier. Even "new" chips might be remanufactured pulls from scrap electronics, so the incoming QA team is there to keep suppliers honest.
So you are right that there is more to a battery than the claims printed on the shrink wrap cover. But the QA process is so much more than just weighing the cell.
lnxpro 5 years ago
Lots of chinese shenanigans going on over there.
BorgOvermind 5 years ago
Seriously ?
That's obviously fake. No such thing as an 18650 with capacity above 3700mAh.
Yes, the weight difference makes a clear fake too, but it's not everything.
I explained things in more detail here: https://xaeus.wordpress.com/2016/09/08/how-to-identify-18650-cell-capacity/
aleggert52 5 years ago
A good article weight of 45g or more is the easiest clue to a fake 18650 battery! Generally speaking most batteries made in China that are labeled over 2600mAh are fakes as to there mAh rating. China's highest capacity for 18650 is 2600mAh as a rule of thumb. There are a lot of fake labeled and fake 18650 batteries being manufactured in China these days. Be sure what you are buying from China. It is worth it to get a confirmation from the manufacture as to the 18650 batteries weight and real capacity in mAh, not peak capacity!
arvevans 8 years ago
High cost Li-ion cells contain a MOSFET in one end that shuts off once the battery gets down to 3.2 volts. This is the MOSFET turn-on voltage and is used to protect the cell from discharge below that voltage. If you discharge it below that voltage (difficult but it is possible) it is very difficult to restart the charge process because the charging current is not adequate to force battery voltage high enough to turn on the MOSFET.
Since the MOSFET "ON" resistance is only a fraction of an ohm it does not significantly reduce battery maximum current to have it in series with the cell.
Many so-called "fake" Li-ion cells do not include this protection device. This lets them actually have more chargeable material inside, and thus their higher than normal current and capacity. But this high capacity comes with a caveat...if you discharge them below 3.2 volts (remember, there is no low voltage protection) the cell may be damaged. Typically these damaged cells will not retain a charge for as long as a virgin cell might, or they might even overheat and catch fire when charging or discharging at high current rates.
On higher cost (i.e. non-fake) Li-ion cells you can usually feel an insulated metal strip down the outside of the cell covering. This is the sensor lead that provides gate voltage to the internal MOSFET switch. So-called ":fake" cells do not have this strip.
DanieleT15 6 years ago
mc172 8 years ago
texas hank 7 years ago
If it's a single mosfet to disable discharge, its body diode would still allow charging of a deeply discharged cell. The safest way to attempt recovery of a deeply discharged cell is to attempt recharge at low current maybe 0.1C or 250mA max for an 18650 for up to 10 hours or so. If it's voltage recovers to normal minimum or more (but don't let it get over 4.2V) congratulations!!! If it doesn't, the cell is garbage now.
Douglas75 8 years ago
Yes, I to got caught purchasing FAKE UltraFire 18650 Batteries. I was able to go back to mu eBay purchase history and discover the FAKE 18650 battery sellers. THEY ARE: ebanlan, hksells, yallstock, led201314, laptopz-outlet, hkiron-aus. I reported this to eBay but received no responses. In total, I purchase 32 batteries which I must re-purchase. Need more info? Just ask.
Douglas
Chris TibbM 8 years ago
You must not know how many Battery manufacturers there are in the word for 18650's . There are ONLY 5. Aspire being the newest, with Sony, LG, Samsung and the Leader Panasonic the rest are simply rewraps of the subsequently lower grades on those 5 production lines Bins A-E A being the best and gets the company TM logo the rest as I mentioned are wrapped by those other companies that purchase from the B-D bins. So in other terms those FAKE Ultrafires are not even Ultrafires lol.
IceC3 7 years ago
Eddieb1213 7 years ago
danleow 8 years ago
Daniel
Chui Lerhern 7 years ago
Thanks for your advice, i got that my 4 batteries bought are fake. But anyway, if the battery is fake,how much is its capacity?
danleow 7 years ago
M.J3 8 years ago
From ebay. 4200mAh, but only 650mAh in use. I was wondering why:
https://plus.google.com/u/0/photos/104329020925538604658/albums/6220722228646169665
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