The "better" chargers I got don't revive a dead cell but some cheap ones do. A bench Power Supply is better to use for reviving them - limit the voltage - just couple secs sometimes.
My Olight Universal Charger has had no problem recharging a protected 16340 cell that has tripped protection, and reads 0 volts. (the battery is not really at 0 volts when that happens, its just blown the fuse)
The fuse did reset, and the battery started charging normally. After a few seconds I disconnected from the charger, and tested the Voltage of the battery with my DMM, which showed it was above 2.7v.
===
doing another test now, to intentionally trigger protection
16340 w built in USB
ran it in an Astrolux S41 on maximum
started out reaching 400 lumens when battery was at 3.6v
after a few seconds, the light stepped down to about 200 lumens, and I then bumped it back up
after doing that a couple times
it stepped down to 40 lumens and would go no higher,
at that point the battery tested at 2.9v
I could not make that light blow the protection by trying to force it to give me maximum mode, it just kept stepping down and getting dimmer
since I wanted to trip the protection, I put the already depleted 2.9v LiIon in a different light and cranked it up to maximum… it produced 140 lumens (on a full charge it does over 400), and a few seconds later the light turned off completely.
I have a dead battery. It reads 0 Volts, and will not work at all, in any light.
Protection tripped.
I plugged in the mini usb charge port on the battery, and counted to 10, then took it off and tested with my DMM.
The battery reads 3.0 volts
I plugged it back in to its built in USB charging port, and it is continuing to charge normally.
===
conclusion
the Astrolux S41 has a step down system built in, that prevented the protection from tripping
my Jetbeam RRT-01 Rotary has no step down system, it just gets dimmer, but when I try to use maximum power, it trips protection and leaves me suddenly in the dark.
Both the Olight Universal Charger, and the built in USB charging port in my 16340 battery, have no problem recharging a LiIon that reads 0 volts after tripping protection.
a couple of details to consider
Using a Protected cell in the RRT-01 can result in the flashlight suddenly turning off completely. This happens when the battery is below 2.9v and the maximum output has dropped to 35% of initial maximum, on a fresh battery.
Since I have a light meter, I often use it to check the maximum output on RRT-01, which is my EDC, instead of opening the light to check battery voltage.
I have learned that when the max falls below 50% lumen output, it is wise to replace the cell with a fresh one, and recharge the one coming out.
IF instead of using protected cells in the RRT-01, I use UnProtected, then the light drops below 50 lumens in brightness, as battery falls below 3.0v. It is then up to me to replace the battery, before the output is so low as to be unuseable.
The UnProtected batteries I use are IMR and INR, they are safer than ICR, which I would avoid unless protected.
Moral of the story
Protection can be tripped by turning the light up when it gets dim (in my RRT-01, but not in the Astrolux S41)
Would the Panasonic (or Sanyo?) NCR18650GA as safe as the INR? I know that those NCR18650GA can support 10A continuous draw. Which I don’t need. I am looking for better safety.
according to this your battery is unprotected NCR chemistry
and according to this it is not as dangerous as ICR chemistry
> I am looking for better safety.
you would need to define your use case risk
for example
any chance you would leave the light on, unattended?
if yes, then you might be better off with a Protected battery, or a flashlight with built in Low Voltage Protection (LVP), that will turn the light completely OFF below a certain voltage… (not just dimming, not just a warning light)
bear in mind that some lights such as Klarus, will claim their light has Low Voltage Protection, when in fact it is just a low voltage warning… this might be a flashing event. That requires that the operator is awake, and able to respond appropriately to the warning.
I applaud your efforts to learn safe practices.
Sofirn’s D25S & SP40 headlamp are decent with low voltage protection
If I was you I’d just get a good brand 18650 and continue to use your headlamp. Switch it off once it dims or use a protected battery
I think the NCR18650GA battery he is considering buying, is a good battery, though I dont really understand all the details of this review:
I know nothing about the batteries he presently has.
And even less about the light that started this educational $eminar
Will do both, planning to buy Sofirn SP40 + good 18650 cells. Current headlamp and its cells would be used as backup and experimentation.
There are several brands and models of 18650 cells. Among those, there has to be one which is safer than others. Maybe that model is not powerful, or cannot sustain high load, but it is relatively safer. That the “safety” I meant. I could order from 18650canada.com but the vendor seems clueless about his products so I prefer the Convoy store on AE (b/c I need to buy an S2+ too). In this store, the 2 unprotected are Samsung INR18650-35E and Panasonic NCR18650GA. Which one would you pick?
Edit: reading the forum post link you gave NCR vs IMR battery - any difference? It looks like NCR is better: quoteing the answer here for convenience:
if one is safer, it is probably due to the chemistry, not the brand
but I challenge you to define the type of safety you are in need of
for some, safety refers to the battery being able to deliver a lot of power, fast… vaping people use that kind of “safety”
but I dont think it applies to your headlamp use
I think your use has a primary risk of overdischarge, even at very low rates… the key is to get the battery, or the light, to turn completely OFF, before overdischarging
so in your shoes, I would focus on Protected Batteries, or Protected lights.
a Protected Battery, can be “unsafe”, if used in a light that can trigger the protection circuit and leave you suddenly in the dark. So again, which light you use with a protected battery, matters…
that is why I suggest focusing on your use case risk scenario, and that is why I caution you to have a protective strategy that addresses the granny fell asleep with the light on, scenario
so now Ive given you two specific failure cases that apply to your headlamp
- it overdrains the battery when left on accidentally
- a protected cell can leave you suddenly in the dark, in a place where that could be dangerous…
soon you will develop your own comfort level and will decide which use case scenario is your primary concern…
for me, using a protected battery in an RRT-01, would protect against overdischarge if I fall asleep with the light on… otoh, it would put me at risk of sudden darkness… My solution is to carry a spare battery, within reach, for the latter scenario, or use an unprotected cell. But that does not protect from overdischarge if Im unaware the light is running unattended.
from where you are now
the next step is to get a tool that can inform you of battery voltage
then do a rundown test
for example
set a 30 minute timer, and run the light down, plotting voltage at each 30 minute interval
when you “notice” the light get dimmer than “normal”, note the voltage…
that will give you a “map” of the voltages you can keep using the battery at, and the voltage at which it is a good idea to replace the cell…
This is one of, maybe the best, protected cell on the market: https://liionwholesale.com/collections/batteries/products/protected-panasonic-sanyo-ncr18650ga-button-top?variant=12534255236
Jon at Liionwholesale knows his batteries. Check out the description and specs on the protection circuit on that page. If I was into protected batteries, this is the one I'd buy. The better PC designs also have lower resistance so you don't lose much in performance (amps).
I do have a set of these, but from like 3 years ago, and they've been improved upon since then.
Oh I get it now. I was more thinking about the safety related to the Li-ion cell like burning or exploding. You meant a more general safely for both the cell and related to the usage.
I don’t do rock climbing in the dark so if the light goes dark for any reason. I have plenty of time to switch to the backup light. Neither I have any needing for “a lot of power, fast”.
The risk related to the light being turned on unintentionally, this could happen but I will make sure this would be almost impossible. In the unlikely event this happens, well, the cell is dead and I will buy another one. At the beginning of this thread, I was concerned that the LED could run the cell below 2.5V without any visible effect (analogy with a gas tank). But it turns out common sense is enough to avoid the troubles. Just to be overkill on the safe side, I would switch to a protected light. Planning on Sofirn SP40 and brand name cells.
After I buy multimeter, new cells. I will definitely do this to get acquainted with the equipment.
all of those things
overdischarge leads to burning or exploding when recharging
repeatedly triggering Turbo demand after step downs is a recipe for overdischarge… this is a typical behavior for some untrained operators
different battery chemistries produce different maximum output capabilities
both batteries in these photos are UNprotected so neither will produce sudden darkness,
both lights were fired on Maximum to measure their output
different lights have different maximum output capabilities, that still vary by battery chemistry
IF you are reasonable in your demand for Lumens (define reasonable as, sustainable for an hour, an output of not more than 400 lumens…), then issues about high discharge rate batteries, are as you said, not relevant to your use scenario.
otoh, if you insist on hitting the Bear with Turbo, over and over, expect your battery to be toast before long… you will be too… lol
There's a usage scenario many of our firmware designs were intended for - what if you are in a pitch black cave on your last cell, you would want to get as many minutes out of it as you can, so the idea is keep stepping it down and never shut it off. Of course LED's have a minimum voltage requirement so there are limits, but again, point is to extend output of light, any amount of light as long as you can. I think this was originated by Dr. Jones.