Some of their lights do. But admittedly, most AA lights are alkaline friendly, low lumen lights.
I love my NiMH but there's no denying that it isn't good to run a AA into cell reversal and this is exactly what can happen with multiple cell lights.
Li-Ions can have protection circuits but I'm not aware of any means of protecting a NiMH from reversal. The trouble with lights using 4 AAs in series (made even worse when we are talking about 8 AAs in series) is that one cell may not be as fully charged as the rest or may be lower in capacity.
The "educated" reading these threads are probably fairly conversant with the need to keep NiMH cells in balanced sets but the wider public at large would not be. Ditto for not running it down until there is no light at all coming out of it.
Even with a "low voltage cutout" of some kind, it would still be possible to put one or two weaker cells in there and damage them even further. (I'm carefull and even I've accidentally done this with my Deerelight Javelin 3 cell body. I was using it as a bike light and didn't immediately notice the switch boot puffing up like a mushroom. Rather alarming and yet I didn't notice an obvious drop in brightness while riding.)
Imagine selling a light using 8AAs to someone who fills it with a mixture of rechargable cells of various pedigrees that they have lying about the house. The cells would quickly be ruined, leading to poor light performance and a generally poor reputation for the manufacturer when the light doesn't live up to its claims.
I was amazed at how varied and how crappy some of my NiMH cells were when I first got my MAHA C9000. Most of them were discarded within a month and I've moved almost exclusively to Eneloops and Imedions now that I have the equipment to test and maintain them.
I think it's a shame that NiMH in C and D sizes (LSD varieties please) are not more common or more affordable. (In fact, I only know of Powerex Imedions as LSD cells in a D size.) Surely it would be possible to design a good driver pulling enough amps from a couple of D cells to compete with the Li-Ion models.
4 AAs in a light like the EA4 - I like it (in fact, I love mine!) but it may be a problem for anyone less careful about recording the state of their eneloops.
8 AAs and even I think it's starting to get into the "too much trouble" realm.
[quote=hank]
lithium-ion battery design variety - Google Search “The term ‘lithium-ion battery’ is now used to represent a wide variety of chemistries and cell designs. As a result, there is a lot of misinformation …” http://www.maple.eece.wustl.edu/pubs/41_JES_Systems_Engineering_Review.pdf
[/quote]
exactly ...+1
Used to use a drill with a cord, then nicd, then nimh, and now lithium. First was a skil, all since have been Makita. The difference in power, weight, run time, charge time, battery life, virtually every aspect of battery usage in power tools is markedly improved with lithium but the fact remains that we use these cells in lights mostly without cell balancing pcb’s or the other whizbang circuitry that makes those benefits possible. It becomes the users responsibility to control and maintain cell management which is not for everyone. I have small damaged hands and weak thin wrists. Even my old 14.4v drills would make them ache driving the thousands of screws that go into a deck. Now, with an 18V impact driver, even with older body parts, it’s no longer an issue. I have 2 chargers and 6 batteries that I rotate through often a few times in a day. Nimhs just could not keep up. I like small flashlights. I like bright flashlights. And I’m willing to watch voltages to keep that size/weight advantage.
Ok, Ill bite...
Would you or Hank like to give those of us without physics degrees the short version of that paper? 
That’s my thing with Li-Ion. I’m NOT willing to watch voltages when I use my lights. For me, a flashlight isn’t just something to show off to friends. It’s a tool that I actually use to light the way while I hike in remote places at night. And the LAST thing I want to have to worry about while hiking down a dark trail in the Sierra on a moonless night is having to pull out my batteries (in pitch blackness) to test them with a DMM to make sure they are not becoming overdischarged. With NiMH, I simply throw in new batteries when my light starts to dim, and forget about it.
Likewise, the whole idea of having to monitor my batteries while they charge just seems stupid to me. I would rather let them charge overnight and have charged batteries when I get up. This is apparently courting danger with ICR Li-Ion batteries. And this is just one more reason I don’t like them. I have better things to do than worry whether batteries for a flashlight are going to start a fire or turn a flashlight into a pipe bomb. Until a battery can be made without these shortcomings, I’ll stick with NiMH. I’m actually quite happy with my Malkoff XM-L2 Mags.
I dont measure my batteries when I'm out. Good drivers have a low voltage warning. Once the light dims, just change the batteries. Of course you have to stay away from lights with multiple cells in series to keep it that simple, but I dont like multicell lights anyway, they are too big.
Long story short: LiIons rule!
I like multiple AA lights (EA4W, PA40, selfbuilts), but they tend to be very big for what they offer and non-edc-able. I think a 1x18650 slimline light is hard to beat in form factor vs. output/runtime.
It only takes a few seconds to check the voltage on say 2 lithium-ion batteries. Not any harder than starting your car and putting it in drive and taking off. People who say they don’t want to check a battery for an excuse not to use lithium-ion are gonna want the short way out on a lot of things they may adventure in life anyway. Like I said, I have yet to have a single issue with lithium-ion batteries when used correctly and I check the voltage afterwards each time. It’s probably even better to check the batteries before charging as well. I probably have as many lithium-ion batteries on here than most users. So what’s that tell you.
I am a carpenter, but, I AM NOT A KNUCKLEHEAD. I have two 14.4v drills, one NiCad, one Li-Ion. There is no comparison. Li-Ion has far more power. Higher discharge is very important in a cordless drill. Also every time I go to my NiCad it is flat, every time I go to the Li-Ion, it has plenty left. It also has only 4 cells as opposed to, what? 12 cells, which I presume means less resistance and they are less weight.
Nothing about my NiCad stands out over the Li-Ion, they have their place of course but Li-Ion is the future.
One other thing I would say is, that like Diesel technology Li-Ion has had a lot more money put into them, mainly because of electric cars and therefore in the coming years you may find Li-Ion leaving NiMh and NiCad behind even more than they do right now.
Marc.
Agreed, lithium ion drills are by far superior to the old nicad, remember to compare a 3amp hour battery to a 3amp hour battery. The handy man peeps buy the half batteries at the store and expect it to keep up with full size batteries. If you believe that I’ve got a bridge to sell you 
I’ve owned 8 drills in the last 7 years, because like flashlights I like to see what’s out there before settling in on one for daily use. Don’t compare apples to oranges and then try and sell me a fruit salad
I prefer to just be blunt and say don’t piss on my boot and tell me it’s raining. :bigsmile:
LoL true that ILF
It’s like the old saying you can lead a horse to water, but you can’t make him drink. There’s a lot of what if people around the world. My buddy who is more blunt tells those kind of people this when they start doing there if this and if that rant.
If my aunt had balls, she would have been my uncle.
No, it’s. ‘You can lead a horse to water, but but a pencil must be lead!’ :bigsmile:
One other point on Li-ion. I’m not sure if anyone has mentioned it yet, but they are cheaper! 4 eneloops cost me £7/8 where as 1 Sanyo 2600mah with similar power costs me half that.
Marc.
Me too!
Conclusion: Not pampering them anymore, treat them just like eneloops instead! Run them flat to the ground, recharge outdoors under a stone trough tipped over at 1/2C, store fully charged for months, then repeat. Why should I care? They’re living a second life anyways; all of my current 18650s have been harvested from years-old laptop battery packs. Besides, they seem to take the abuse quite well. Still holding their charge, and delivering over one hour of usable light from an XM-L U2 driven at 1.5A. What more could one ask for?
Note: I do not have any torches using more than one single 18650 at a time; otherwise I wouldn’t be so reckless.
I can well imagine that low quality cells are the major worry, but what I’m reading by people far more knowledgeable than I am is making me nervous.
Look at this for example:
“If say your battery terminated at 4.2v [ Normal ] , and after one hour is still holding 4.2v , then your battery is in good shape . If say the battery drops to 4.19v after one hour , then this is rather normal , as would be 4.18v , well within acceptable levels of voltage sag after charging .
Now lets say the battery sags to 4.15v after terminating at a measured 4.2v , then the battery quality - condition is really not so great , and is showing sign of more internal resistance than should be considered normal . If the battery were to sag to 4.12 or lower , then I would suggest replacing the battery or keeping a very close eye on it . ”
Scource:
http://old4570.com/extra/batterywarning.html
What strikes me about this is that we are talking about just hundredths of a volt. The tolerance margins seem slim.
Multi-cell lights appear to be a particular problem, needing a Digital MultiMeter to take battery voltage readings.
You raise an interesting point about laptop batteries.
In order to remain “on topic” without veering off too much, it looks to me as if Li-Ion is still very much the favourite, but that Nickel certainly has it’s supporters, and there may be fertile ground for a certain smallish level of drift away from Li-Ion.
What type of percentage increase in AA cell capacity and brightness are we talking about?
4aa batteries keeping up with one 18650, is not keeping up. Look at the size difference of the batteries
I’m EDC’ing a Nitecore EA4 at work, and the holster sticks out far enough to make it cumbersome. I love it but its bulky, it’ll be downgraded to a coat light once the thrill of how new it is ends.
I think your too stuck in the details, I check my batteries once per charging cycle, sometimes once per two charging cycles. Batteries that stop holding a solid charge, get disposed of.
If you want to stick to primaries or Nimh, no one is holding a gun to your head.
Just means your flashlight options drop drastically if you limit yourself to one chemistry.
Inside every laptop battery pack is a BMS (Battery Monitoring System). It monitors the voltage on each cell and controls charging and cell balancing. It is the reason laptops don’t blow up more often. Lights that use series connected cells have no such monitoring system. They are a disaster waiting to happen.
And, people, what’s so difficult and onerous about checking a cell’s voltage before and after charging? It only takes a couple of seconds and is well worth the trouble.
Thanks for clarifying that issue. 