Li-Ion or NiMH?

Ok guys, I get the impression that Li-Ion batteries are not the popular choice. Seems to be NiMH? I've done a little bit of reading and it would seem that Li-Ion batteries are "better." Are the choices of batteries and chargers available all fire hazards or have I just stumbled across a few isolated cases while surfing different forums? I'd like to hear from the experience here on the forum (hence my joining so I can learn) on which type of batteries and chargers to get if you were me. I've got 5 flashlights on order and they'll all use 18650.

Before considering the NiMH batteries, I've read suggestions on the WF-139 charger and the Pila IBC. I definitely want one that won't charge the batteries too fast and decrease the life, shuts off when the batteries are charged, can analyze the batteries, etc. and I'm not necessarily looking for the budget model. If a quality charger costs more, I'm ok with that.

Any advice on where to purchase batteries and charger is also welcome.

I've got my notebook handy ready to take notes. Thanks in advance for your help!

Hi there jb1, I'm definitely not a battery expert, but here's a few ideas:

If you already own or ordered 18650 lights, I think you don't really have a choice but to use Li-Ion. To my knowledge, those lights require the much higher voltage provided by the Li-Ion chemistry. And there are no commonly available NiMH equivalents of the 18650 size. Somebody please correct me if I'm wrong on this.

I personally only use NiMH AA and Alkaline AA batteries. The best NiMH batteries (Eneloop or Duraloop are the surest bet) store a lot of energy, last for hundreds or thousands of recharges, and they don't discharge themselves very much in storage. And there is less danger involved if you buy a cheap charger. Mine cost $4. ;) For my purposes, another advantage of NiMH is that it usually gives better runtime than Li-Ion.

sb56637, thanks for the reply. All of my 18650 lights are on order. Any lights I have now came with batteries. Ugghhh. So now begins the task of figuring out which batteries and charger and place to purchase. I sure hope I don't have to get them from overseas while my new flashlights arrive with no batteries. Talk about torture not being able to fire up a new flashlight.

Hmm, if you don't want to wait maybe you could look on

^ i tend to disagree with some of what sb said. i found run times to longer on flashlights using li-ion. see what you need to realize is there is ALOT more power in Li-ion (and various lithium chemistries) than a Ni-mh can provide.

18650's offer great runtime. most are in the range of 2000-2600 mah at nom 3.7 (up to 4.2)

using the nominal battery voltage, thats (on the high end) 9.72 Wh

compared to a AA Ni-MH at 2500 mah and 1.2V = 3 Wh

not a fair comparison?

14500 = 900 mah at 3.7v = 3.33 wh (consider its LIGHTER, slightly smaller, and a lower capacity than a QUALITY 14500)

18650 is a great form factor too. and safe under decent loads.

the pila is a NICE charger, my gripe? PRICE!

i like the trustfire chargers myself, but have ordered a hobby king charger/discharger as an ultimate replacement

sb IS correct on 18650 equivalents, however the closes ni-mh in that size is 4/3A, which comes approx 3800 mah

comparitively, the longer, slightly narrower (approx 17670 size) is only 4.56 wh. half that of the 18650!

OH i take that back

4/3AF is 18650 sized. and sadly the same capacity as the 4/3A. sorry. 4.56Wh.

better off with the 18650!

a safer alternative (for those who are careless with batteries) to li-ion, is li-fepo4. or LiFE batteries.

they are not WIDELY available yet, but offer a more stable chemistry.

as long as you dont DROP, overcharge, incinerate, over dishcharge, or lack care for your li-ion batteries, they will be just fine.

if you own a cell phone, laptop or other battery operated device, it is of li-ion chemistry. perfectly safe when buying quality products.

keep the 18650 flashlights, and get some good quality 18650s and charger (whatever you can afford. ive heard great things about the xtar wp2)

also, tenergy's ni-mh charger might be a good investment anyways

i have that one and its a GREAT smart charger/discharger for ni-cd/ni-mh

also look into powergenix Ni-Zn (future replacement for ni-mh) it has a nominal voltage of 1.6, better for your high power demand electronics. you can pick these up at Big lots (white charger and 4 batteries is 8 bux!)

what ive done is:

own 2 Ni-zn chargers and over 8 AA batteries

own tenergy ni-mh charger and:

4x D sized Tenergy 10,000 mah ni-mh

4x C sized Tenergy 5000 mah ni-mh

tons of energizer, rayovac, and sanyo ni-mh AA and AAA

own Trustfire TR-002 (i suggest getting the 2 battery version, but only use one bay)

own Hobby King charger/discharger (waiting for it in the mail)

and the following batteries

18650s trustfire flames (mixed luck)

14500 Trustfire flames (great luck)

16340 Trustfire flames (ok luck)

16340 Trustfire blue (good luck)

and other various sizes.

ill be ordering Tenergy 18650s soon, as i love their non-li-ion products ive ordered!

xP.1337, tons of info. Thanks for the detailed response. I also forgot to mention that I *think* I want to get protected 18650s. With respect to the charger, I'm looking for a "smart" type of charger that won't allow me screw them up by overcharging them. I probably won't drain them as these flashlights will be used to goof off since we moved into a new house and I'm surrounded by woods on 3 sides. Plenty of darkness out here once the sun sets. The town I live in has some type of light pollution policy so our subdivision is pretty dark.

So I'll just be lighting up the back yard and trying to spot critters running around. I'm pretty particular about taking care of my toys so abuse, dropping, etc. hopefully won't be an issue. I just don't want a charger that will overcharge or catch on fire. That's really my biggest concern with Li-Ion.

I picked up a Sanyo charger and Eneloop batteries at Costco. Haven't plugged it in yet but I knew it was a good deal so I snagged it. Would my new lights run on the AA Eneloops?

they MAY run, but the battery would be super loose inside, so probably not. keep those eneloops for things like remotes.

the costco deal was a good deal, my problem is i already have LOADS of ni-mh, so i decided against it.

even tho they stay charged, i buy 100 packs of Utilitech AA and AAA alkalines at Lowe's.

the Ni-zn is also a great deal. so if you can, go to Big lots and pick up a set.

as far as a good charger, the pila is the best li-ion you can get besides a universal charger like the one from hobby king (which requires you to make your own mount for the battery)

so ifyou can afford it, go for it.

the trustfire chargers trickle a little after they turn green, so i just watch them. im still waiting on my hobby king charger as i stated lol

also, if your that dark, consider modding a spot light too

at big lots i picked up a 12V spot light for $20 (tho im pretty sure the battery is WICKED old, cause it charges and discharges far to quick) and used an HID and ballast from a set for a car with an H3 base. less than 10 min mod, and that thing is BRIGHT!

brightest flashlight i own, probably 2000 lumens OTF easily. if not brighter (rated at 3200 lumens)

I remember seeing that thread. I've NEVER run across a smoking deal like that. I do have a Thor 10,000,000 and a Cyclops 15,000,000 spotlight. The Thor doesn't work. I don't know if the battery or the bulb died. I'm hoping that by joining this forum I'll be able to learn how to either fix or upgrade the dead one. Unless it's a drop-in, I have 0 mod skills currently. LOL

I'll go check out the Pila charger - thanks for the advice.

the hobby king has an accucell6 this is it or some version of it ,, down side is it doesn't come with a power supply and you have to either have a 12 volt Laptop power supply to mod or just a regular 12 volt power supply.. It also doesn't come with a way to connect batteries to it .. some have used magnets on the ends of the wires , others will tear up an older junky ni cad charger etc and use it as a host ..when they say hobby they mean it .. the hobby king one was 32 $ think before x mas .. they don't come with manuals eother but don says he'll copy his for you if you need it done .. i have the trustfire 101 because it charges everything ,every size , but I watch em and charge only when I'm in the room . .. I don't know about lipos i don't think they are recommended for high discharge .I know rc car guys use them and they are reportdly safer but I've never even heard anyone using them for flashlights .I think capacity is lower too ..

Most people are running the trustfire 2600 flame 18650 from Deal extreme ..lots of people have had very good luck with them for the price they seem to be one of the best bang for your buck . lithium does have a life span and so newer is important .. It's a huge topic . i think you were really smart to score some eneloops , if your lights are 18650 lights no thing else will work except possiblt 2 cr123a primaries . but make sure the emitter is rated at over 6 volts or you'll burn it up .. I remember those days when i had lights ordered that needed batteries i didn't have ..Welcome to the insanity ..

Boaz, thanks for the info. I'll check out the batteries on DX - I was afraid someone was going to say that was the place to get 'em. I sent them an email last week regarding the status of my order. No reply. Must still be on holiday. As far as modifying a charger - that's probably something I shouldn't do because I have no idea what I'm doing. I appreciate the info but at this point in time, I'm one of those people that would be better of buying something that works from the minute I open the package. My wife would ____________ (insert violent act here) if I burned our brand new house down farting around with a battery charger. LOL

I haven't dropped mine, but... now I'm really scared

There is no real danger. But it is best to treat lithium cells with respect. They can do bad things if seriously abused.

But as long as you don't puncture them, try to charge them if they are below 2V (It might work, but don't try this indoors), or cook them, they will almost always fail gracefully and harmlessly.


The obvious newbie question is "when the batteries are being used in a flashlight, how does one know if they fall below 2V?"

Wouldn't a "smart" charger alert you that they were too low to charge? If they fall below 2V, is it safer to throw them away?

Sorry for all the rookie questions - I'm just trying to get a handle on this topic so I don't hurt myself or my home.

My experience with li-ion is very good. I scavenged the net for info ona good (noon house burning) charger and found out that XTAR indeed makes good chargers at a decent price. Pila charger is out of my budget but XTAR MP1, and WP2 are awesome. Once you try a good 18650 flashlight is hard to go back to AA's if not for car or pocket flashlight. My advice woudl be to get better li-ion cells not the cheapest yo ucan find. I find myself pretty happy with XTAR 2400mAh and Hi-max 2600mAh which are perfroming very well. Both protected. I have a few sony unprotected that i use only on a bike. I like my teeth to stay where they are supposed to. More than once i left the batteries in XTAR charger overnight and when i realized the idiocy i immediately checked the voltage. The highest voltage i got was 4,20V.

Safety tips:

- Never damage the cell.

- Never heat it over 55 degrees celsius

- If the cell does not work as expected by a decent margin - dispose it

- Stay away from ultracheap cells of unknown manufacturers

- Prefer protected cells instead of unprotected ones if you don't specifically require the unprotected ones. More peace of mind.

- Store cells in cold dry places at 3,7-4V not empty not fully charged. Nothing bad could happen but you will most certainly degrade them faster.

- Use decent chargers and pull out when charging is complete.

A lithium ion cell is essentially empty by 3.3V - the light will most likely go out and if not, will have dimmed dramatically. It'd be hard to miss.

Any cell I think I've over-discharged I'll leave to stand overnight to see if the voltage will recover. If it doesn't reach 2.8V after standing with no load on it, I'll toss it.

Some chargers will - my hobby chargers will refuse to charge anything where the voltage is too low - this also applied to my car battery the other day. I can force it to do so, but you have to know that you are doing it.

The RC model guys are much nastier to their batteries than we are, pulling crazy currents from them and then charging them at very high rates. The tradeoff for this is short life of the batteries. They will give great performance that way, but they won't live for many cycles. And they do tend to burn up at the end of their lives.

Charging to 4.1 instead of 4.2V will increase the cycle life of a cell by several thousand cycles.

Most exciting things happening to lithium cells happen when they are charging. It is a good idea to charge them on something that can take heat, just in case.

I've never had anything exciting happen unless I deliberately caused a wrecked cell to fail. 24V at a lot of amps through an RCR123 will do it every time. Don't try that indoors. Or where you can't get away and upwind from the resulting burning mess. The gaseous products of cells burning up are extremely bad for you. This is one of them.

But like I said, it won't unless you make it do so. It is most likely to happen in high current devices using multiple cells in series. Such devices need to be treated with a great deal of respect and the cells carefully balanced. In practice the only LED lights where this is likely to be an issue are SST-90 lights. Mostly these have multiple cells in parallel rather than in series so as to keep the cells to sane discharge rates - it is mostly the 250-1000W incandescent bulb guys who have these sort of problems.

As I've said before:

You are more likely to be killed by a dead fish dropped by a seagull in the middle of the Sahara Desert.


I'll go check out those batteries you mentioned. I've read good things about the XTAR as well. So in the winter, I'll keep the batteries in the insulated garage. We don't get very cold here in the southern U.S. In the summer, I'll bring them inside the house because it's over 100 degrees (F) often. Usually high 90s at the very least.


NOW I finally know what your tag line means. LOL. I'm starting to get the idea. I thought, what's the point of getting a charger if you can't charge it when it gets (too) low. I understand now that I probably won't drain them that low. It would be nice if the charger showed the volts the batteries were at while they were charging so I could pull them at 4.1.

Do you know if the Pila analyzes and/or re-conditions batteries? I'm not sure of the phrase I'm looking for but "re-conditions" comes to mind.

Hey guys. I am giving my friend Norm the UltraFire WF-502B that came as a set with a charger and battery. It's the one that had UlrtaFire on the white gift box. Laughing It will be his first 18650 li-ion flashlight so I want to also print him a list of things NOT to do just for safety reasons. After reading this thread I put this list together so please check to see if it is accurate and if I need to add to this list. Thanks guys!


- Don’t overcharge more than 4.2v (100% Charge) Check voltage with multi-meter

- Don’t let cells sit in charger after charging is done

- Don’t over discharge below 3.2v (Check voltage with multi-meter)

- Don’t drop, damage, puncture or physically abuse them

- Don’t incinerate them

- Don’t get them wet (water and li-ion DO NOT mix)

- Don’t leave house while charging cells

- Don’t expose to heat over 100F

- Don't charge hot/warm batteries - let them cool first = per Don

I am also adding this to the list:

4.2V = 100%
4.1V = about 90%
4.0V = about 80%
3.9V = about 60%
3.8V = about 40%
3.7V = about 20%
3.6V = empty
less than <3.5V = over-discharged


Good info for rookies like me as well. I'll print it out and put it by my charger.

You might want to wait for a while until the other members check and double check it. They might have additions to this list.

Jepp, wait for old4570 to arrive .... he is our go to guy when it comes to batteries.... I only own 2 x 18650 Hi-Max (protected , from 1Ebay 6Ebay ) which are supposed to be the successors of the WOW 18650 which old4570 tested on .