Yes, I am lucky, it could have been much worse. These were fairly new batteries with less than 10 charge cycles on them. I have several other brands of protected cells, Orbtronic, Soshine, Zebralight, etc. and have not tested the protection circuit on any of them. Many others have however, posted positive results on several of these brands. Not sure if HKJ actually trips the circuit in his testing, or just reports the manufacturer claimed over-discharge point on the cells he tests.
I trips the over current protection, but does not rapport or test on the over discharge and over charge protection.
Generally these protection circuits uses a chip with all the 3 protections in it.
These chips can be bought with a lot of different voltage threshold, but they do all have the same 3 protection functions.
Overcharge, overdischarge or short them? ;)
No, please dont. It could be that it works sometimes but not everytime. Just keep on using it.
Just treat ANY cell like it was unprotected. As I said, the protection is a safety feature and should not interact with regular use.
Makes sense.
I’m currently running my Uniquefire UF-X8 on high (somewhere between 2200 and 2800 mA) with one of my new Panasonic 3400mAh protected 18650B cells. We’ll see if the protection kicks in. If I see it getting dim I’ll immediately stick it in the charger and assume the protection didn’t work. Or, if I never post here again, you’ll know what happened to me…. 
Another question: Does the rated capacity of protected Li-Ion cells (like 3400 mAh on mine) refer to absolute capacity of the cell after crossing the danger line, or can it safely provide 3400mAh before the protection kicks in?
OK, I’m still alive, and the protection circuit just tripped. It’s now on the Intellicharger, and appears to be charging (currently one of the three yellow indicators is flashing.)
I hope you also have a DMM? ;)
3400mAh is the rated typical capacity (minimum for these cells is 3250mAh) but at a given C-rate (I think 0.2C, so 680mA) and down to 2.5V.
Some can deliver more if overcharged or overdischarged, but thats not healthy for the cell.
Depends on the current draw from the battery but they should be close. The pcb should kick at the upper and lower voltage limits of the cell. If it doesn’t then its not being very useful. At higher current draws (Say 3amps) the cell will have a greater voltage sag, so the pcb should trip early giving you less useable capacity. At lower currents you should get close to the 3400mah. They are rated by Panasonic at a certain temperature, at a certain discharge current to achieve there rated capacity.
They should provide the advertised capacity as listed here.
http://www.industrial.panasonic.com/www-data/pdf2/ACI4000/ACI4000CE54.pdf
I had this kind of failure on protected cells and since then I don’t use them because they are too long and they damage soft springs on your flashlights or if you have fat thick spring and protected battery comes as a very tight fit into your flashlight and that same thick spring will dug(press it hardly) your protected cell and destroy protection.
This will happen in all flashlights that are tight fit with strong spring.
Manufacturers are not putting protection on their cells by default right? So any protected cell is result of other people job, and although I would really would like to thrust famous battery companies (re wrapping experts) they still IMO probably put cheap China protection circuits inside? I am not sure that I can thrust this small piece of electronic.
Of course that some guys will make better protection on cell with better care but just imagine mass production of protected cells. Probably people work on norm, and place for failure rate is big in this case(probably 10% if not more)
Overdischarge is not dangerous at all so if you destroy cell just hit yourself with palm in your head and buy another one, and be more carefull next time.
Overcharge? This could be the biggest issue with this cell. Cheap China chargers could work for years but you never know when they will screw things up. I had case where cheap charger pumped sanyo 2600 to around 5V(more or little less i am not remember) i fall asleep… Charger had red light(it should be green)and it was hot in the morning when I awoke. I put that on dmm and was shocked. Threw that charger(universal 2 channel charger 
) into garbage and since then I am buying single channel one and so far so good… Btw this cell is still working great It did not explode.
This should be one of main rule while using unprotected or protected one: Charging cell should be strictly under your supervision, and if charger chargers 1 or 2 hour(red light) longer than usual take damn thing out of the wall!
I am not using protected cell but it is logical solution to recommend it to most people. But don’t rely on protected cell. I think charging under your supervision is best solution to prevent disaster.
So Unprotected vs Protected? Very queasily question…
This is similar as airbag in a car. Will it open? You never know but it is good to have it.
Good protection circuits are made by Seiko, Japan. Thats what most quality brands (Keeppower, AW, Enerpower, Eagletac etc.) use.
That is so wrong. You can easily discharge a cell down to 1V and have it recover to 3.4V again. It might be internally defective though. Now you measure it 2 hours later and see "oh 3.4V, thats low, better recharge it". You put it in the charger, because of the internal short circuit the cell gets hot, the wrapper burns, the charger burns etc. You say "charge only when watching" but will you really unplug the charger if you have to do something else for 30min?
I would have disposed that cell, but hey, its not my health.
I only use unprotected cells and I'm sure I know how to deal with them. But I'm very happy there are protected cells out there. I started using protected cells and after a few months I sold them and got unprotected cells.
Thanks on info NightCrawl,
I am not sure I got you on overdischarging issue. I had few newb(me personal and few friends) cases of overdischarging long time ago on crappyfire brands but that cell never worked again, I even tried to recharge them and stil nothing… No signs of life… So I just threw that away, and advise everybody to dispose that kind of cell.
So if cell overdischarges will it return to 3,4V after 2 hours without charging? I am not getting that in your post.
” You say “charge only when watching” but will you really unplug the charger if you have to do something else for 30min?”
If I have 30 minutes job in meantime there is no need to unplug it. But if any job occurs it would be good to unplug it… You never know when you will return…
If charger charges 1-2 hour more than usual I will unplug it from the wall, and I think it will not made to big damage to cell like in my above mentioned case overcharging whole night because I fall asleep… Maybe I should add this to above mentioned rule “never try to charge battery when you are sleepy”.
“I only use unprotected cells and I’m sure I know how to deal with them. But I’m very happy there are protected cells out there. I started using protected cells and after a few months I sold them and got unprotected cells.”
Yes and I am very happy that protected cells are out there but I will stick to unprotected ones since nanjg likes them better
If you actually manage to drain a cell down to 0V, then yes, it is crap. But you said "crappyfire", so maybe those were protected and the protection just didnt reset. In single cell lights, you wont get a cell below ~2V, in multi-cell flashlights.. depends on the number of cells. It is possible to discharge an unprotected cell down to 1.5V (for example) and having it jump back to 3.4V within 1-2 hours. It has happend and Iwouldnt put such a cell anywhere near a charger again.
Well, a damaged cell can go wild within 30 minutes or less. As I said, it might get hot and burn some stuff. So if you are in doubt about the condition of a cell, get rid of it. The risk is not worth the 5 bucks.
Nanjg doesnt care if your cells are protected or not..
Thanks on explanation,
It is very fascinating how voltage can return from 1,5 to 3,4V without charging. Hope it will not happen to me
Well my 3A nanjg (single cell light) performs better with unprotected cell… It works with both but performs better with unprotected.
Light meter measures little more lux on unprotected cell. Sanyo 2600 vs protected 2600(marsfire) I think same sanyo is inside it.
LiIon cells voltage recovers once the load is removed. That's part of the problem.
At 3A you should not be able to measure a difference with fully charged cells.
We all have to commit to making some effort to get valuable reusable materials back into the Supply Side of this carnival ride we’re on. Either that or tolerate higher prices…
Don’t even think about it. Just send it on its way & get another. There are plenty where that one came from, and they’ve gotten much better since that one was made.
If we all put one hand in the water and push together, we can make the whole ocean move.
That’s what I think, but you know I’m just…
Dim
Looks like I’m going to have to retract this statement. The PCB didn’t trip, but rather the UF-X8 apparently has low voltage protection. I stuck the almost dead cell in a P60 flashlight and it fired right up and kept going and going and going… until I could look at the emitter directly, still dimly illuminated, at which point I got scared and pulled the cell and put it on the charger to get the voltage back up. Both a “protected” XTAR 18700 and a “protected” Panasonic 18650B from BangGood behaved this way. So this leaves me wondering, is undercharge protection working on these protection circuits?
Maybe you didn't get the voltage down enough. You could have measured the voltage under load and it probably was at 2.8V. XML2 has a higher Vf than XML, so maybe it's not possible to trip the protection with this specific led.
That could be. These are both XM-L (older) lights. I just assumed that if the LED was that dim, the voltage must be really low. But I’m probably wrong, and my next purchase will be a decent DMM so I can test this a bit more. Thanks for walking me through this with patience.
I'm surprised nobody has gifted you a DMM yet. :P
But a cheap one is good enough for LiIon cells, unless you want a good one anyways, its no harm to have one.
Cant recommend you one though, you are like on the other side of the world.
If you really want to trip a protection, its easier to use 2 in series. But dont do that without a DMM. ;)
Just ordered one of these. Should be good enough to check voltage anyway.
You’re right about these protection circuits working with multiple cells in series. As a matter of fact, I already managed to test this by accident a few years ago when I first received my XTAR 18700s. If I remember correctly, I inserted two of them with unequal charges into a 2x18650 (in series) 3xXM-L light and ran it on high. The protection circuit on one of the cells (presumably the one with a lower charge) did trip and probably saved me from some indoor fireworks.
You are truly living the budget spirit, you could buy a decent DMM locally for 10 bucks but decide to order from China to save 1 buck. *g
I doubt you would have seen fire. But maybe one of the cells would have died.