Perhaps in a dive light, but the plastic clicky switches are not solid.
Millions carry cell phones and whatnot in their front pockets right next to their family jewels, so I would think fire is a danger.
+1
It depends on the battery and charger.
I inserted an Asucell the wrong way into a cheap “travel” charger. The pcb on the Asucell burst into flames.
It doesn't need a dive light.... standard Ultrafire's are sufficient. Standard cell phones might also do the trick. Again the chances that something like this is happening are very slim to none, but better be safe than sorry... right? Nobody was injured by reading about battery/cell safety so far. A good indicator is that you aren't able to buy round LiIon-cells in retail stores German retail stores yet, so most large retail sellers are not taking the responsibility to sell them to the masses.
You are right that there are reports about cell and battery fires, but the fires need at least needs a few seconds to minutes to develop. Pipe bombs go from click to boom in under 2 seconds, if the circumstances are right. I don't like aluminum shrapnel particularly.
Man I really do sound like CPF... don't I?
Not true, I have seen 14500 and 10440 at walmart. 18650 at tractor supply co and 26650 has been seen by other members at fry's. :)
Hello, I am new to this forum. Currently generally reading and learning new things etc.
Actually I just saw this thread and just registered to ask this… Now I am worried about ultrafire batteries because I recently purchased 4 pieces ultrafire from lightmalls. See link below.
I want to ask is it really that dangerous? I am going to use (multiple) 2 cells in my flashlight that I also recently purchased.
Thanks in advance.
The details:
4-Pack UltraFire Genuine 18650 3.7V 2400mAh Rechargeable Li-ion Battery(4pcs)
UltraFire 18650 li-ion rechargeable battery.
Capacity: 2400mAh.
Voltage: 3.7V.
No memory effect.
Short circuit and over-current protection.
Can be recharged over 500 times.
Low internal resistance.
Environment friendly: no toxic waste.
Widely applied in Telecommunications, Audio and Video Devices, Information Devices, Electric Bicycles and Miner Lamps.
The main way it’d be dangerous is if the batteries were very different capacities, so as they are discharged from 4.2 to 3.5, the voltages would be different. And then they start charging each other while discharging, it’s a recipe for disaster. There are some genuine ultrafires though. The fakes will just take old used laptop batteries, which use 18650’s and repackage them as ultrafire 18650’s.
A way to tell if yours are similar capacity is to take a multimeter to your batteries. Measure the voltage of each one before you put them in. Then run the light for say, 15 minutes. Then check the voltages of each cell. They should all be within about .01 volt of eachother, for my Crelant, the battery closest to the head is always .01 volts lower than the one near the tailcap. If they aren’t very similar voltages, then you’ve got a problem. Multimeters are really cheap, harbor freight has them for $5. And I got mine on amazon for a total with shipping of like $8 just 2 or 3 weeks ago! But chances are that someone you know has one. But you really should get a multimeter if using multicell lights.
Sorry to worry you or anything, but ultrafire cells have a big risk to being fake. Maybe someone can credit lightmalls to having genuine ones. This thread they sell fake ultrafire stuff though.
Alot of people buy old laptop battery 18650’s, and not a lot have problems. But most use them in single cell lights, so the only downside to them is very low capacity possibly.
I agree with you , agenthex, that it’s not as simple as oops, BOOM!!! A lot of things need to happen for that to occur. However, from the user’s prospective, it will take on the appearance of oops, BOOM!!! Secondly, I’d say that the fact that something bad didn’t happen on occasion a, b, c, d, and e, doesn’t mean that there is no cause for concern for those circumstances. I’ve flicked hundreds of cigarette butts over the balcony, with no problems whatsoever. Does that mean it’s safe to do so? No. About a month ago I did it, and I set the mulch on fire. There were flames four feet high. Fortunately, nobody was injured, and there was no property damage (other than to the mulch). But yes, starting a mulch fire is unlikely. That having been said, the consequences are potentially dire, and I won’t be doing it anymore.
Yeah that light looked like a pipe bomb all right, if by pipe bomb you mean something apparently much weaker than an exploding plastic cell phone. Note the reason for the injury is that the cap blew off (presumably when he was holding it). Apparently not even protected cells: Ultrafire 18650 3000mA exploded | Candle Power Flashlight Forum. Perhaps likely one of the cells wasn’t even charged.
A water heater/boiler is likely far more dangerous overall than a lithium light. Certainly a lot more people are burned/injured than by perhaps similar numbers of li-on batteries. If CPF had a thread for everyone who ever got a hot water burn then it won’t even be predominately about flashlights anymore.
Sure, it’s entirely true that the li-on chemistry isn’t 100% safe. That doesn’t mean it’s 0% safe either as often presented by chicken littles. It’s just safer overall than cars, water heaters, cigarette butts, etc, etc.
I used to be paranoid about charging after reading CPF’s warning threads, but then I actually thought about the actual risks instead of assuming CPF is right about anything.
Just another example of how paranoid CPF is: There is a nihm charger model BC700 by Lacrosse (I have one). When some design flaw was found on CPF (basically in its failure mode a power fet is left on and “burns”). This quickly turned into all out hysteria on the forum thread much like the lithium cell threads. However, it’s one of the top nihm chargers on Amazon for a long time and likely has sold hundreds of thousands in total with maybe handfuls of problems. Surely flawed and maybe dangerous if you’re extremely unlucky, but hardly an epidemic that it’s made out to be.
Do you still buckle your seatbelt ?
Agenthex, maybe I can put your mind to ease by clarifying my goals for this guide. It’s not my intention to scare people off of using 18650’s. Nor is it my intention to prevent people from buying discounted cells. All I’d like to do is give people a list of a few easy-to-implement best practices for using the technology safely, and provide food for thought when considering what cells to buy and where to buy them.
I’d also like to give a little bit of a heads up for the consequences one might face if they choose to be willfully ignorant of the safety guidelines. You’ve read the stuff, have experience buying and using the technology, and have decided that the risks are acceptable. All I’m shooting for is a quick crash course so people can have a quick read, and still be reasonably assured that they have the pertinent information as to what the risks are, and how to minimize them.
The more relevant analogy is if you avoid being around cell phones, cameras, etc because they ALL use potentially explosive li-on. The low risk tolerant in our hobby can mitigate it by buying protected cells.
Please answer the question.
Ignoring a risk and mitigating it are far from the same thing. Perhaps you should read from the link in your sig more often.
Sure:
- buy cells and charger of somewhat known quantity (ie those reviewed somewhere to be not fake, instead of lowest price mystery ebay special)
- don’t use dissimilar / unprotected cells in multi-cell lights
That’s it.
I think I can come up with a better list; but that’s why I’m writing this guide. Let me know when I’m done if you think I did ok 
Made a tiny bit of progress. I think I’ll leave it here for tonight. Let me know if there are any mistakes
Here’s the thing: If this were a forum for overprotective soccer moms, it’d have a list of do’s and don’t of how to protect your children from splinters, bicycles, and strangers in ice cream vans.
There’s also a reason why soccer mom’s are stereotyped the way they are.
It’s anyone’s individual prerogative to write whatever they want, but personally speaking that’s not the image I’d want to cultivate for myself.
You’re a friendly sort, aren’t you?