I just received 4 x Panasonic NCR18650PD. They were all exactly 3.55V.
Well, that same 2900mAh cell, from the “reduced charge loss if used in high drain situation” info given above (if accurate) would be OK there, because I doubt you wont be in the “high drain” category for your high lumen lights.
I don't recall this being the case with mine, but I've just started recording this info so I can really be sure. I typically recharge my cells once a month, and last time none of my six 2900's were below 4.19V. I didn't charge this time, so it'll be interesting to see how much they self discharge by the next charging day.
I have a modified Solarforce M3 that pulls 4.28A, pretty much use the PDs exclusively. I have several of them, guess I should check the ones that have been sitting for any length of time and make note of their charge level in relation to down time.
Nice info, thanks!
Makes me want to pick up another half-dozen…
>>>> don’t recall this being the case with mine, but I’ve just started recording this info so I can really be sure. I
It’s not just me. There are other threads here on BLF where others have had the same results. If you have 2900s that hold a 4.20 charge for more than a couple days without the warming trick, you are a VERY lucky minority. Or maybe they changed the catalyst chemistry?
“I have some brand new factory fresh ones that do the same thing. Voltage falls to the 4.17V area and stays there.”
As you can see in that thread, those are where my 2900s came from. I don't know about this warming trick you speak of. Maybe I am lucky.
Please look this thread. Thread is about to help me decoding date code of Pana 2900 NCR18650PD from FT.
It has strange X symbol unknown in panasonic code table. So could it be fake?
Look here:
I don’t think they are fake at all. Just the Panasonic numbering system. We have to find a way to figure it out and decode it. Maybe an E-mail to Panasonic Li Ion division?
Where did you get the batteries? I trust Fasttech most of the time, but who knows how reliable their suppliers are.
If you have “REAL” 2900s, you can sometimes tell by the positive poles. Each company makes slightly different poles. If they don’t look exactly like the other 2900s you have, I would say there is a good choice that they are fake.
It’s not for everyone, but that’s one of the main reasons that I get 99% of my batteries from packs. Big companies like Acer will be getting their batteries straight from manufacturers like Panasonic and Samsung.
The PDs from FT are just fine. They are exactly the same as the ones I get from DoingOutdoor. They both have those same symbols. I believe the date codes are printed right on the metal battery cases. Sometimes if you hold them right, you can see it through the wrapper.
>>>>> I believe the date codes are printed right on the metal battery cases.
Yes, you are completely right. Well, at least they are on Samsungs. The stuff printed on the label on Samsungs is useless. Just machine used, that kind of thing. The date codes are ON THE CAN.
Sometimes you can see through the label more easily if you use a …… drum rolll …… flashlight!!! Just need to find the right angle.
Or just sacrifice one battery for the bunch and peel the wrapper off. Recover the battery with aftermarket 18650 shrink tube, available on ebay. Don’t go anywheere without it. 
Which symbols?
Can you see symbols on mine and compare it to symbols on yours in this thread?
Anyone?
>>>>>Can you see symbols on mine and compare it to symbols on yours in this thread?
Once again, for Samsungs, at least, the numbers are ON THE METAL BATTERY CAN. Not on the label. The label stuff is useless, for samsungs anyway. They are UNDER the label. Near the positive end. Three lines of alphanumeric code.
You need to look carefully, closely and try to see through the label. If you can’t see through the label, you’ll probably have to remove the label to see the date codes.
At least they’re that way with Samsungs.
I looked a little bit online and saw a bunch of people “guessing” how to decode the Panasonic code, but nothing really from Panasonic.
I’ll look more later if I have time.
Hope this helps.
I can find nothing on how to read the can codes, if in fact they contain the dates. I do strongly suspect they do contain dates though.
Here is everything you need to know about panasonic li-ion cells, EXCEPT the date codes.
I found the panasonic date code explanation that is cited in this thread on several sites, but not on any Panasonic site that I could see.
I unwrapped a 2900 to see if were more codes. No, there are just three lines of alphanumeric codes. With a little creativity, I could get them to read anything I wanted.
So what the mysterious “x” means is anyone’s guess.
Yea, I saw that one.
Can’t help but think it must have changed by now. Those date code instructions are 11 years old. There has to be newer instrcutions, even if they are the same instructions.
Yes, my guess is there is a revised/improved date code in which they replaced 0 with X (this follows the 11=Y, 12=Z pattern and removes possible O/0 confusion). However, those cells with the X also have two stacked letters above the code and beside the big letter, which none of mine have…so it may be a different naming convention.
OK, I ordered batteries. I just got tired of looking and placed order for the Panasonic NCR18650A 18650 3100 mAh protected.
At $16.86 it was a bit more than what I wanted to spend, but after talking to someone who has a TN30 (ordered) about what would fit it, I decided on these.
This morning I got the TK75 in the mail, so now I will have enough good batteries for both.
these cells are really ageing very well. just recently got some of these gray panasonics. one is even exceeding 2900! this is at 3A discharge!
if anyone’s still doubting that electric car batteries last 10+ years this should change your mind. these are mostly 2008 2009 production so almost 10 years sitting in some warehouse most likely not at ideal storage temps
It certainly does look like they age well, reading my messages above yours it looks like I got my cells back in 2013, 4 years passed already, wow! The laptop pulls of the same type I got all still seem to be functioning very well. I don’t use them as frequently now though, since I have higher drain cells for performance and I am not hiking in the dark as much. But when I use them, (recharged yesterday) they are still reliable and going strong.