This came up in another thread. I had never seen a official charge rate for the NCR18650B. So I did some searching and found this datasheet.
http://industrial.panasonic.com/www-data/pdf2/ACI4000/ACI4000CE54.pdf
Link for those who don’t have a PDF viewer.
I had always assumed the charge rate was the same as the NCR18650A. The datasheet says a std charge rate of 1625ma, a little less than .5c charge rate. The NCR18650A was listed on the datasheet at .3c or 930ma charge rate. From what I know about how batteries are made to achieve a higher capacity in the same size package this shouldn’t be correct. As the capacity increases the discharge max current should decrease along with the charge rate. Does anyone know how they achieved a higher capacity while the charge rate was increased?
HKJ I would like to hear your input on this. Does std mean standard charge rate, that’s Panasonics suggested charge rate for a NCR18650B cell?
Actually 1625mA is exactly 0.5C of the nominal capacity, so thats fine (although the C rate is sometimes also related to the minimum capactiy, seems random..).
Standard charge rate is what it says, the charge current Panasonic uses to rate the cycle life (and so on) of the cell.
From what I know, Panasonic made some rather big chemistry changes allowing for a better performance and higher capacity. Its still a very safe cell but keeps a higher voltage under load. Up to 5A its about as good as the NCR18650PD.
Thanks NightCrawl for the info. I did go to HKJ site and compared the voltages between a 3100mah and a 3400mah in the same brand. So hopefully they used the same PCB. From what I saw in the comparison the 3100mah cell was not all that much different in discharge voltage. There was a slight advantage to the 3400mah but not as much as the older 2900mah. The 2900mah seem to hold its on with the 3400mah except for the efest black 3400mah brand. The efest seem to perform better than the rest, maybe a better PCB. All the comparisons I checked where at a 5amp discharge.
Panansonic has improved the charger rate, maybe in the chemistry or maybe in how they plate it onto the electrodes.
Std. charge rate is the rate where the cell has the specified parameters inclusive cycle count.
If you can get the full data sheet, it might also list a maximum charge current, that is the maximum safe charge current, but it will reduce the lifetime of the battery. These data sheets are difficult to get for Panasonic cells (I do not have any).
Thanks HKJ, this was the first time I had actual seen a datasheet for the ncr18650b. So the charge rate is becoming higher with higher capacity cells. That’s good news for some applications that depend on charge rate in the design, like a electric car. It does seem like they may be a shift in 18650 production from high capacity cells to cells with higher discharge rate and better charge rates.
Thanks again HKJ, for all the great information you have given us. 
Electric cars need high energy density.
When you have a couple hundred strings in parallel, you already have high current capability.
They also need to be charged in a reasonable amount of time which looks like they have improved upon (better design) with higher charge rates while still retaining more capacity.