Ding ding ding! BU-409: Charging Lithium-ion - Battery University
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That does not apply in this case as it's impossible to recharge a cell that's never been charged.
Why not buy some protection circuits and put them on before you use them in series? Nobody can really tell you “its safe” running those in series, we can’t know if you’ve gotten close to hitting the “negative lottery” or not. It just makes more sense to at least protect yourself with protection circuits on them if you are going to use them and they started out at .88V. I have cells I harvested from a new laptop battery at 2.6V and I don’t use them in series either, I use my protected cells.
Ok then ok, i’ll scrap the idea of using them in series, everyone’s swayed me. Will just use them as singles in smaller flashlights or power packs for charging things like phones.
What would be some decent cells (preferably protected i’m guessing?) that i could get for use in 3x series?
Stick with name brands (Sanyo, Panasonic, LG, Samsung) from reputable suppliers. DX is not the most respected seller, but they still have a pair of protected Sanyo 2600's for $8.36 (less if you buy 3+ pairs). I took a chance and ordered two pairs (just over a week and they still haven't shipped). I highly doubt you would beat this price. Shipping Li-Ions from overseas is kind of questionable right not too. Are you in the US? If so, look at Mountain Electronics or Illumination Supply.
-Garry
Yeah, i usually do stick to name brands. I’ve been looking at DX for a while now for cells.
I’ll think about getting a couple sets of those cells.
I’m in the UK, so my choices of usual stores are a bit limited
“Name brands” for batteries is different from say clothing in that if you buy a non name brand pair of jeans it may not be stylish, but it will probably still last a long time, and function exactly like the name brand, whereas with batteries if you buy a non name brand battery it will probably not last a long time, have much less capacity than it states, not deliver as much A of power, and may fail very much sooner (or outgas/explode), but will function just like an average person expects at first in a stock LED light like a Trustfire. At least at first.
I do understand that, I’m a computer parts guy myself and I know all too well the dangers of going non-name brand just to save some cash. Almost always go for reputable brands for peace of mind
What folks are scared of is the cells being poorly matched. What you need to know is internal resistance, not capacity as someone else said. This could be a good excuse to get a hobby charger, or wait a little while longer for a smart charger to come out that will let you know the internal resistance of your cells.
They all came from the same battery pack and have the same serial, i guess that would be considered matching?
Nah i don’t care any more, i’ll get some cells that i know i can rely on, probably those linked sanyo’s from DX, then just use these as singles
When they're brand new they should be matched very well. Time and use may have changed that. Knowing internal resistance is still good to know since it lets you know when you should discard cells.
The reason people aren’t going to “OK” your idea (which, however, you can do whatever you want) and give “approval” is the risk is increased for a mishap, which could cause you severe bodily harm, who knows, maybe death. The chance is very low, so its up to you. Yes the cells probably were matched for the laptop battery pack. But you have to understand that any risk is multiplied in a 3x light and the possible “damage” is also multiplied. And they are old, who knows what happens in age (increased modifier), and they were discharged to 0.88 (another increased risk modifier).
Here’s why: ONE cell with a problem/very mismatched can “go off”, and this risk is therefore tripled, since any one of 3 is 3x compared to one alone. Now remember, this is modified by the risk of age and the risk of over discharge, and if for example both factors triple a small chance, then your increased risk is 3x3x3=27x. Next, it could cause the other two cells to also go off, which means any possible damage/explosive force is tripled or more (no I don’t know the correct explosive formula, I just know its bigger). Now, its probably extremely rare that anything like this would happen, but the fact of the matter is, is it really worth it for you to give a triple multiplier, or 27x, or to who knows how large a multiplier factor to even a rare chance, especially when you are also increasing the base explosive force possible of that chance? Even if it were one in a million say (which I have no basis for its just an example), its possible your over discharging batteries could have 100x the chance to “outgas” and maybe one is old and has a fault 10x ing the chance, so you multiply that by 3 and actually end up with a chance that’s more like one in 330. Probably nowhere near that high, but I don’t know, who knows what the real risk percent is, nobody in their right mind is going to say “sure, go ahead, its fine!” on that basis. 
Psst, i’m not going to use them in series, it’s ok, no need to persuade me any more
I will remember what everyone’s said here though, in case i ever need to build an improv pipebomb hehe
NP, I was waiting on a break and thought I’d illustrate the risk a bit. I know its tempting, thinking about it this way helps me.
This goes out to everyone here:
Or you could just ship them to me.
I promise to keep you Safe.
I will post pictures of any and all damage they cause, as soon as the Doctor lets me.
If you ask, I may work very diligently to destroy one of them in a disturbingly violent manner, and post the video on YouTube for all to watch.
This applies to all new, chargeable cylindrical Lithium-Ion batteries of any size. (except the ones made by Saft! I’m irrationally prejudiced against those low-current bastards!)
That’s the safest route of all! Guaranteed! Even if you come over to watch, I’ll protect you; with my life if need be. Only my camera will ever be at risk. Best of all, I’ll do it all For Free! That’s right, a 100% Guarantee of Safety at no cost at all to you other than maybe a little postage.
Easy, right?
Yeah, right.
going to make lots of photons and post the outdoor tests on youtube eh?
to the o p.
if those hold voltage well say a week they are probably ok.you need an entry level hobby charger like a REAL imax b6.
otherwise you dont know if those are good or recycling bin fodder.
You can stack li ion…but they have to be balanced
The laptop battery circuitry balances the batteries (your’s were left “dead” way too long)
Single stack, keep the batteries in mated pairs, use them together, discharge them together, mark on A, the other B, then swap them when you use them…they “condition” themselves as a mated pair, it still ups the “chance” that something catastrophic can happen…but keeping them together can help lower the risk
Best thing to do is educate yourself on Li Ion batteries
http://magazine.sfpe.org/content/lithium-ion-battery-hazards
There is a TON of education out there…you just gotta go get it 
That may come back to haunt you, or not.
To be fair to the new guy, who just signed up to start this thread, he really is keeping up with his homework, from his replies. His nickname seems to be the ironic opposite of himself, kinda like me, and a lot of us here.
Maybe I’m wrong, but speaking of a lot of us here, before I get misunderstood, let me put in my vote for 1S LiIon configuration ONLY, please! Scrounge cells are flat-tops anyway, which are hard to connect Serially. One cell, one LED, y’all; it’s a Natural Thing!
But this is the special case we all dream about. 4.3v batteries, matched at the factory — and about “name brands”… these are “name brand” batteries, the name of the brand is LG, and they are highly respected by most people who know what they’re talking about. These are even sturdy enough to run a 4.3v standard charge! The horde under scrutiny was put together by Dell, so it’s not inconceivable that the Serial Numbers are sequential. The “balancing” has been done — by pros! All the OP would need to do is keep pairs mated & watch his assets… sorry…
Best of all, as per the OP statement here:
we’re clucking and coo-ing over brand-new, virgin, 4.3v, 3AH 18650s!! Is anybody else a little envious?
Sorry to interrupt. Back to sniffing glue and building that one-hand-only dead-short rig for Intrinsic Safe testing…
PS: the Protection Circuit Upgrade is a Danged Good Idea anyway, regardless, whatever. For Safety’s sake!
It’s ok i agree with ya’ dimbo! Have entirely given up on the idea of using them in serial!
They do look like pretty healthy cells though… the first pair that i charged 6 days ago have only dropped 0.01v each, and i think that was them just settling, were probably on the lower boundary. 
I’m not so sure about sending them to you for destroying now… hehe
For protection of the cells. Since i’m only going to be using these LGs as singles now, is there any point looking into getting any for them, would it be worth the hassle?
On another note, the tr-3t6 i ordered arried today (exceedingly fast postage from china, quite confused and happy there) and it’s built like a damn tank. The quality is superb. And the light that it chucks out… yikes! If this is any sign of what’s to come, i might have just caught the flashlight bug, uhoh.
Oh, it also came with a pair of ultrafire cells, supposedly 4800mAh (yeah right!). I don’t suppose those would be matched, so are you lot going to tell me to not use them in this either?!
I’ve ordered 3 pairs of panasonic 18650A protected and sure enough, they don’t have them in stock, i get an email after 10 days!!! So i just canceled the order 
Ah damn was that from DX? I might think twice about buying from there now then…