Decided to Go Unprotected

[tatasal]

This is taken from a Panasonic Lithium-Ion Batteries Technical Handbook:



■ Structure
A lithium-ion rechargeable battery consists of a spiral structure
with 4 layers. A positive electrode activated by cobalt acid
lithium, a negative electrode activated by special carbon, and
separator are put together in a whirl pattern and stored in the
case. It also incorporates a variety of safety protection systems
such as a gas discharge valve which helps prevent the battery
from exploding by releasing internal gas pressure if it exceeds
the design limit.

Hope this releases the pressure gases in our minds!

 

[Shadowww]

This is taken from a Panasonic Lithium-Ion Batteries Technical Handbook:



■ Structure
A lithium-ion rechargeable battery consists of a spiral structure
with 4 layers. A positive electrode activated by cobalt acid
lithium, a negative electrode activated by special carbon, and
separator are put together in a whirl pattern and stored in the
case. It also incorporates a variety of safety protection systems
such as a gas discharge valve which helps prevent the battery
from exploding by releasing internal gas pressure if it exceeds
the design limit.

Hope this releases the pressure gases in our minds!

The problem is that when people see report of e.g. UltraFire cell exploding, they immediately think that ALL Li-Ion's are unsafe.
They don't even begin to think that high-quality cells may have safety features, which cheap/crap cells don't.
I've never seen a report of Panasonic, Sanyo, Samsung or LG cells explode, unless abused in horrible way (e.g. NASA had to overcharge Sanyo cells to over 10V to make them explode (and even then, only like 1 out of 10 did), in their Li-Ion safety testing report).

 

[tatasal]

The problem is that when people see report of e.g. UltraFire cell exploding, they immediately think that ALL Li-Ion's are unsafe.
They don't even begin to think that high-quality cells may have safety features, which cheap/crap cells don't.
I've never seen a report of Panasonic, Sanyo, Samsung or LG cells explode, unless abused in horrible way (e.g. NASA had to overcharge Sanyo cells to over 10V to make them explode (and even then, only like 1 out of 10 did), in their Li-Ion safety testing report).

So very true!

 

[DonK]

This is not about $

You can get the cheaper Panasonic based protected cells (Orbtronic etc) for about the same price as the unprotected Panasonic cell. $2 more at most.

The issue for me is the trade off between reliability, safety, and potential cell damage.

Reliability is better with unprotected cell - no additional electronics to fail, or come detatched.

Safety is clearly better with protected BUT the chargers being used have protection features too - so unless they fail, the cell protection features are not needed.

Cell damage due to over-discharge may be an issue in some applications, but single cell flashlights are the ideal application to natutally avoid over-discharge - what other appliance constantly keeps you informed of battery condition ? The most recent cells have lower base voltage limit (2.5 now, down from 3.5 just recently).

So, going forward, I see cells continuing to improve to the point where protection is not essential - we are almost there with the latest Panasonics. Chargers will improve too. Appliances - especially lights, will have min voltage cut-off built in (this is already happening on new models - take the cheap new Fenix E35 as a good example).

Protection circuits on the cell are now not essential, and within a year will be totally obsolete due to advances in charger and appliance design. Just my predicion of course, but you gotta watch the trend and run with it, not against it.

 

[Shadowww]

This is not about $

You can get the cheaper Panasonic based protected cells (Orbtronic etc) for about the same price as the unprotected Panasonic cell. $2 more at most.

I can get unprotected NCR18650A's at under $6/piece - mind showing me protected 3100mAh batteries at under $8/piece? Cheapest I can find is $23/pair (Keeppower-branded), which is 2x the cost of unprotected cell.

 

[sidecross]

I can get unprotected NCR18650A's at under $6/piece - mind showing me protected 3100mAh batteries at under $8/piece? Cheapest I can find is $23/pair (Keeppower-branded), which is 2x the cost of unprotected cell.

I bid $20/pair for the Keeppower and use them on all my lights running on two and four 18650 batteries; I also use Eagletac 18650's 3100mAh batteries on my multi-cell lights that the Keeppower height may be an issue.

This is more a question of knowledge and experience; if your light is running on just one unprotected battery it may be worth the savings in cost. If you are using multi-cell lights then this is an issue of more than only cost.

 

[DonK]

cheapest I've seen those cells is about $10

 

[kwak]

I use protected cells in my lights that don't have a low voltage cut-off and non protected in all my lights that do.

It's not just the price it's also reliability and fitment as 3100mAh protected cells and bigger do not fit in many of my single cell lights.
Unprotected ones drop straight in though.

But then i have been using far bigger and far more powerful lithium batteries for many years in my RC vehicles NON of those are protected and a 5000mAh 10S (37v nominal 42v fresh off the charger) carries a damn site more power in it than a little 4.2v 1S cell.

Totally agree, I mean there is no way keeping my fingers intact is worth the extra $5 per cell. I need that money to buy more flashlights.

Yet there is a good chance you have a cell phone, laptop, tablet etc and all those will use lithium batteries very few of the batteries themselves will have voltage protection and yet you sit with a laptop on your lap and a phone next to your ear

I've seen cars burnt to a crisp from folks incorrectly charging LiPo's, i've seen planes and helicopters burst into smoke while flying and cars burn till they were just a molten blob on the floor.

By far the worst i've seen though is when a NiMh pack literally exploded while it was being charged on the owners passenger seat.
The car was a complete right off.

Lithium cells will smoke then flare up like a Katherine wheel type firework, the only time they explode is if they are inside a tube that is unable to vent.
When i'm not using all my torches i back out the tail cap.
1/ It stops the battery discharging by breaking the circuit
2/ IF the cell fails in that state it will allow it to vent

I do this on ALL my light, protected or unprotected cells, lithium or NiMh.

 

[Norm]

Lithium cells will smoke then flare up like a Katherine wheel type firework, the only time they explode is if they are inside a tube that is unable to vent.

I personally have experienced a cell exploding like a fire cracker when it was accidentally charged on the wrong setting, this was in the early days there was a commonly available charger which charged Li-ion in series, (we now know that's a no no), the cell was a Chinese 14500.

Similar to but black.

Norm

 

[iron potato]

I use NCR18650B unprotected cells in SC60w & SC600, used to lockout when not in use. (and other electronic switch flashlights)

Protected cells for series connection flashlight or without low voltage cut off / indication driver.

 

[Overclocker]

i just experimented with a Thrunite T30 and an unprotected cell. it gave off warning flash starting at about 2.9v and continued all the way down. i stopped the test at 2.31v

if left overnight it would still go lower

if you have a particularly low Vf it would probably overdischarge even lower

i don't wanna babysit my lights. i want fire and forget. that's what the protection circuit is for

 

[DonK]

I can live with that. If you get a warning at 3v and you can go down to 2.5 then what is the problem. Unless you leave the light on and unattended. Something I will not do.

 

[Overclocker]

I can live with that. If you get a warning at 3v and you can go down to 2.5 then what is the problem. Unless you leave the light on and unattended. Something I will not do.

exactly. babysitting

 

[DonK]

My point is WHY would anyone turn on a light then walk away and leave it. Sounds like that person would need a babysitter. Such a person would not keep a light for long, so what kind of cell they used would be a moot point.

This is akin to saying that you need a car that shuts off the engine when you get down to 1/4 tank of fuel just so the tank does not run dry when you walk off and leave it running.

 

[Overclocker]

Something I will not do

famous last words LOL

 

[march.brown]

My point is WHY would anyone turn on a light then walk away and leave it.

Some people keep torches in their backpack/rucksack/suitcase when travelling ... These cases do get thrown around or knocked about during transit ... It is quite possible that occasionally a torch is turned on accidentally ... So simply carry the batteries out of the torch just "in-case" (pun intended).
.

 

[Joe Talmadge]

Obviously, different people have different judgements of risk, and different risks. To me, if I have two protection circuits (cell and light) instead of just 1, I'll pick that every time. But then again, for me, there are a host of variables out of my control: 1. Despite being told "don't touch the lights in this box", sometimes I come home and one of the kids is using that light, 2. spouse might grab a light and she is capable of nearly anything, 3. I might turn a light on low during certain situations and fall asleep, 4. I might start some work with a light, leave to go grab a drink thinking I'll be right back, then get distracted in the house, 5. etc. etc. etc. I think there's uncontrollable variables for everyone, but maybe I'm wrong. I'll keep with 2 layers of protection everywhere I can, maybe that's not right for everyone

 

[archimedes]

Obviously, different people have different judgements of risk, and different risks. To me, if I have two protection circuits (cell and light) instead of just 1, I'll pick that every time. .... I think there's uncontrollable variables for everyone, but maybe I'm wrong. I'll keep with 2 layers of protection everywhere I can, maybe that's not right for everyone

Redundancy is a critical issue in designing safety systems ... "Two is one, and one is none" :thumbsup:

We're glad that cars have both brakes and airbags, right?

Safety engineers look at situations from the perspective of "worst-case scenario" (what must fail for a hazard to occur), not the opposite (if everything works properly and as intended).

 

[Shadowww]

Redundancy is a critical issue in designing safety systems ... "Two is one, and one is none" :thumbsup:

We're glad that cars have both brakes and airbags, right?

Safety engineers look at situations from the perspective of "worst-case scenario" (what must fail for a hazard to occur), not the opposite (if everything works properly and as intended).

Too bad that protection PCB on a battery can't be compared to brakes nor airbrakes, because the way cells are protected increase changes of failure in single-cell lights.

 

[archimedes]

Too bad that protection PCB on a battery can't be compared to brakes nor airbrakes, because the way cells are protected increase changes of failure in single-cell lights.

Actually, airbags can increase the risks of certain types of injuries, too ... everything is a balance of benefit versus risk.