[ASK] Li-Ion NCR18650BF 18650 cell, is it really made by Panasonic ?

[BravoV]

All this time I used only NCR18650B (green jacket) which is rated 3200 mAh according to the official Panasonic datasheet.

Recently bought new one as seller claimed its 3400 mAh, named NCR18650BF (with "F" suffix) , red colored jacket, no readable text printed what so ever at the label. 

Only few really faint markings like 3D code and some dented text at the plastic jacket. Also there is a word "SANYO" printed at the jacket, although very faint. I thought Sanyo brand is gone as it's battery division is swallowed by Panasonic, cmiiw. Also this supposed to be new manufactured stuff, not an old stock.

Close up photos attached below.

As currently I don't have any Li-Ion battery analyzer to check its capacity, is this real / genuine cell made by Panasonic ?

Also about it's datasheet, I'm aware there is one circulating at internet, but that is not 'official' datasheet, and can't find it at Panasonic web site either.

[dmwahl]

Bought on ebay? Amazon? Unless you bought it from a reputable supplier there's a decent chance it's old, recycled, or otherwise not new. I don't know if Sanyo still makes these, but if not that would be another bit of evidence that you didn't get what you paid for. My guess is that it's an old Sanyo cell of unknown origin. Could be new old stock given there don't seem to be weld marks on the terminals, but probably no way to know for sure unless the seller tells you, and then probably no way to verify it.

[TheDirty]

The Candle Power forums is probably the best place to ask.  They follow this stuff pretty deep.

[HKJ]

It looks like the new Panasonic/Sanyo cells are sold with the Sanyo brand and wrapping, i.e. that red wrapping where it is very hard to read the text.
For some reason many LiIon datasheets are confidential and usual not posted on the internet by the manufacturer (Panasonic has mostly been posting short from datasheet).

[zlymex]

NCR18650B and NCR18650BF rated the same capacity at 3350mAh according to Panasonic. 3200mAh is the minimum.

[peter.mitchell]

if they were less than say $4 usd they aren't likely to be legit.

[Siwastaja]

No way to really know without testing. Fortunately, this is state-of-the-art technology with high enough capacity, so that counterfeits have very hard time being even close, so capacity reading alone will suffice. If you don't have a tester available, consider discharging it manually with a high-power resistor, two multimeters, pen and paper and a bit of patience to sit down for an hour. A 1.2 ohm resistor would give you an initial current of about 3.5A, dropping to less than 2.5A near the end. Calculate A*(h/60) every minute and accumulate the result until discharged down to about 2.5V.