https://www.google.com/search?q=lithium-ion+battery+design+variety
“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
The world is moving rapidly toward Li-ions. I am the only one moving away, well me, Bubba and Ennis are, LOL.
The biggest selling battery type in the US is still Alkaline (unless you count Lead Acid, which is the number one selling battery type, but not for flashlights). Lithium is "predicted" to overtake other rechargeables of the sizes we use, but if you take into consideration all of the batteries in use, including laptops, phones, tools, etc. With all of them being counted, Lithium (of some sort) has already taken over the world.
It’s not just the matter of chemistry… My battery preferences would look like this:
Yup, that’s how it is for me - I’d rather stay in the dark, than ever go anywhere near a *Fire-labelled Li-Ion battery.
But with NiMH, I have no concerns at all using cheap chinese cells - worst that can happen is that I’ll be left without light in a inappropriate situation, but that’s better than being left without a hand (or, considering that I carry my EDC in front pocket, even something worse).
That’s not true either.
NIMH can blow up as well as lithiums. Might not be as likely. No battery is completely safe. But I can tell you I have tons of lithium ion batteries. I have yet to have a problem of any blowing up. And all hold their charge for months and months. I have messed around with some doing things I shouldn’t have to make them do some crazy things. But that is on me. I now buy all the good batteries like the top end Panasonic and Xtar that way I know I am getting good top end Japanese cells. The top end Panasonic lithium-ion cells will easily give far better overall results than the best NIMH batteries. And for durability I would say lithium-ions will hold their own as well.
I love both Nimh and lithium ions, and I’ll continue to use both happily. Lithium will always have more punch for there size, and both Nimh and energizer lithiums because they don’t leak.
I’m developing second thoughts about whether Lithium Ion batteries are suitable for my use. I’d always use protected cells, but I had plans on buying multi-cell 18650 torches, and I feel that checking the voltage on the batteries, especially with such accuracy, before putting them into the flashlight, is a bit beyond what I feel comfortable with.
I’ve been reading old4570’s advice:
http://old4570.com/extra/batterywarning.html
amongst other advice, and the sensitivity, the low tolerances, required in “nursing” the Li-Ion batteries is making me nervous. Also, it seems a bit of hassle, more bother than it’s worth for me.
I suspect I may, regretfully be moving away from Li-Ions, though I’m not sure.
And yet, 18650s are in my laptop. I don’t understand why they can be so safe in laptops but so risky in flashlights….maybe it’s because as old4570 says “the number of counterfeit batteries and some seriously low quality offerings have made Li-ion more dangerous than it has been for a long time ”?
There are protection circuits to prevent over charging and over discharging the cells.
Some flashlights protect the batteries from over discharging them too. There are protected 18650’s too, for double protection you can get one of those and run it in a flashlight with its own protection circuit (or minimum voltage requirement that it won’t run when the battery drops below 3 volts)
Nimh AA are the best for throwing them in and run them till the flashlight dims, if that’s what u want.
I find that very worthy of note - your order of preference, especially 1 and Infinity.
Maybe if I just bought Sanyos and Panasonics, etc., from reputable sources, I would need to worry vastly less. Even so, these brand-name batteries would still need to be “nursed”, if used in multi-battery lights, something I would find a bit bothersome. Duh.
Thanks. The matter of overdischarging Li-Ions is another issue. Some torches apparently cut out if the voltage drops below - I think it was - 2.7 volts - but I thought that was too low to be OK.
I need to check this out more.
2.7 is as low as you can safely go with a quality cell. If your not willing to buy a multimeter and treat flashlights like a hobby, then don’t buy multi cell 18650 flashlights.
I’m a full blown flashaholic, I love multi cell lights, making sure the batteries are balanced in between charges is all part of the routine for me. I use single cell lights at work, because they are edc able (every day carry) I have a lot of flashlights, but don’t have a favorite battery chemistry.
I think I only have a couple of functional lights that use primaries. All recent purchases are centred around li-ions, their just more compatible with led’s, run time and pocket rockets. :bigsmile:
These nice AA lights make it possible for those that don’t like to use 18650s to have similar lights without feeling so left out, but they won’t make anyone stop using li-ions to switch to ni-mh.
Actually, Panasonic’s NCR series (and couple other, less popular ones) have no problem going down to 2.5V.
Thanks for the heads up Shadowww 
Well I don’t know about you but many people have moved from Africa and lions ages ago.
Just kidding.
How about your cellphone and laptop?
Switch them back to NiMh?
I don’t think so.
More care? What care? Do I have to polish my 18650s? I didn’t know.
Batteries have protection and devices have a protection or should have one as well.
That protects the batteries from over discharge and overcharge.
Chargers actually neat for Lions, like the ML-102, I can’t say I’ve seen one like that for Nickle based batteries. It’s usually something bigger and in a pair.
Plus the power stored in a lithium 18650 vs an NiMh AA/14500?
I’m too sleepy to do the calculation but it’s going to be quite a few times more in the lithium 18650. Also NiMh AA will not ever give you the current a lithium 18650 can.
3.6V @ 3A?
vs
1.2V @ 9A?
I don’t think an AA NiMh, Eneloop or not can give you 9A/10.8W.
Of course for general use lower output is fine and there are AA lights around.
Why don’t we see high capacity low self discharge NiMh 18650s? Just upsize the so praised Eneloop. But it just can’t compete with the lithiums in that format.
I wasn’t aware of that. I did notice most suppliers ship Li Ion at 3.6v rather than fully charged which I thought was for shipping safety. I have been in the habit of recharging cells when I return from an outing so they are ready to go next time. Is that a bad practice? I guess if storing them fully charged is not good, then it would be best to have some sort of charger that can charge them to 3.6v for storage? Fasttech sells some dual chemistry chargers with a switch: 3.6v for LiFePO4 and 4.2 for LiCo. If you want to charge your 18650 LiCo’s for storage then would it be best to put the switch at 3.6v and charge them that way? Should fully charged cells be stored in the fridge?
I only know what I've read here, other tech forums and in "the other flashlight place that dare not be mentioned here" 
I'm not sure about setting a charger to a different voltage but you could manually spot check your cells as they charge. Some chargers have a voltage meter that reads output during charge - I have a couple of Cottonpickers units like this.
Alternatively, you could drain some charge before storing - about 40% of capacity is regarded as optimal for long-term storage.
Interesting, my Lenovo ThinkPad has the ability to program the charge parameters for the battery. I have mine set to terminate charging at 90% and resume at 70% meaning I have a higher number of partial charges. Various Lenovo forums suggest utilising this in order to prolong battery life.
If you haven't been there, batteryuniversity.com is a great resource. Have a look here:
To quote from the link above...
Lithium-ion suffers from stress when exposed to heat, so does keeping a cell at a high charge voltage. A battery dwelling above 30°C (86°F) is considered elevated temperature and for most Li-ion, a voltage above 4.10V/cell is deemed as high voltage. Exposing the battery to high temperature and dwelling in a full state-of-charge for an extended time can be more stressful than cycling. Table 3 demonstrates capacity loss as a function of temperature and SoC.
Again, horses for courses - Li-Ion cells have their advantages in high powered applications, but definitely need more care than NiMH unless money is of little consequence to you.
Well, that’s very interesting, thanks for the info. So I think unless I’m counselled otherwise, I’ll drain the cells that I have sitting around fully charged, and stick them into the charger with the switch and set it to 3.6v and place them into storage. Perhaps I’ll just keep one set of cells ready to go at any given time.
Do these rules just apply to Li-ion, or is it the same for LiFePO4?
Agreed. I think alot of people just don’t appreciate NiMH batteries for what they can do. They can kick out boatloads of amperage for high powered lights. And the low voltage (vs Li-Ion) isn’t something that can’t be solved without just using multiple cells. No, the light won’t be quite as small. But seldom am I looking for th tiniest thing out there. And alot of the time, I like the feel of a larger light anyway.
Of course, one thing that kind of kills AA lights is the fact that they are generally designed around alkalines rather than NiMH. Because of this, many AA lights just don’t put out. What we really need are more AA lights specifically designed around high current NiMH batteries.
I think Fenix fits the bill on that , their lights are maximized for the NIMH I believe.