I have a newbie question. unprotected batteries, I know you are not supposed to discharge them below a certain point. How will I know if I am/have and also, do these batteries discharge over time with them sitting inside the flashlight with the light turned off? If so, what is the best way to store these batteries and maintain them?
Any knowledge on both protected/unprotected cells would be greatly appreciated.
Sort of depends on the light but most 18650 lights will dim as the voltage drops. You shouldn’t discharge batteries below 2.7V (2.5V for some models) but a light will lose access to the higher outputs as the voltage drops and by the time you get down to 3.2V you’ll probably only have access to the lowest 1 or 2 modes so it’s hard to intentionally over discharge a single 18650 light/battery during actual use. 2x18650 lights are a different story and will possibly not drop in output as the voltage drops (depends on make and model though).
Depends, all electronic lights will drain the battery with a stand-by current but that stand-by is typically very very low and would take like a year or a little more to actually drain the battery. Lights with a mechanical switch won’t have this since the mechanical switch physically cuts off the connection to the battery. There are some models though with a mechanical switch that still has stand-by drain like the Klarus XT series due to the internals of how it’s designed.
Do you have a DMM? [Digital Multi Meter]That is an important tool to know the health of your batteries.
Most of my batteries are Unprotected high drains needed for my Modified lights. Every new light I get I do an incremental Max run time test. I measure the voltage after each increment. When the batteries are near 3.60v, 3.50v at the lowest I can see how much time that is so when I am on the trail I know when to switch lights or change batteries.
With a little knowledge and effort their is no reason a battery should get too low of a voltage.
Also, many lights have low voltage protection. This is very helpful for the aforementioned UP battery.
I have been on these trails w/ my Husky so much that I know how long it takes to get to certain points. And for those who do not hike nightly just look at your watch and know that, for example I can use this light for 40 minutes on max and the voltage will be ~ 3.58V.
Most manufactured lights only have a Low Voltage Warning though and no actual protection (Acebeam, Fenix, Nitecore, Olight, Klarus, Sunwayman, Jetbeam, Manker, Niteye, Rofis, Thrunite).
Armytek, Eagletac, Zebralight, BLF lights, and a few random models from the previous manufactured names do have built-in protection but I don’t have a definitive list. There might be a few more but nothing is coming to mind at the moment.
Ok,ALL of my modded lights and a few stock have low voltage warnings.That is what I was thinking of.
Then my simple steps[run time tests] are the solution to enjoyment and safety.
TBH I never depended on a lights built in protection/warning.Again ,because of my simple and valuable run time tests. If one is aware, no need to beware of dead batteries! lol!
I've never let any of my batteries run low enough to see any LVW in my lights. I keep an eye out to make sure it never gets that far.
Agreed!! Nether have I. :sunglasses:
That is the whole point of me doing run time tests when I get a new light.I know my lights[and batteries] very well. No lie here. I have guessed EXACT voltages of my batteries numerous times when getting back from the trail.
My Husky and I have logged over 16K miles on the trail. :+1: That would be ~ 8K at night since I walk him twice a day.
It is so routine and easy to get to know the limits of my lights/batteries. Not just that, I bring 3 or 4 lights each night so none of them have a chance to be entirely drained.Variety is the spice of life!
With all that we have said, this is about the OP who is asking for suggestions and who does not have the experience that some of us may have.
Yeah, for the most part it’s hard to over-discharge an 18650 unintentionally during actual use. But it’s possible through accidental activation in a bag or such where it’s out of sight.
This. 
Unless I’d be stuck in the woods at night or in a maze of twisty little passages, all alike, I’d never let the light run down to vapors.
Only once did I somehow manage to run down an S2+ that got dimmer and dimmer, ’til LVP started blinking the light.
And for some lights, the resulting smoke and eventual fire would be sufficient indication that the light was accidentally bumped on.
Thanks for all the answers!
So, the difference in the unprotected and protected is only in the discharge? or you have to keep an eye on the unprotected when I charge them as well?
Get a proper charger. They stop at 4.2 Volts.
I have only protected 14500 because i use them in lights that also work on AA batteries, protected to avoid them being discharged too far.
Other lights have Low Voltage Protection or at least Low Voltage Warning, no need for protected batteries.
Protected cells won’t let you discharge them below 2.8V while unprotected cells could be discharged below their lowest recommended safety voltage if left unattended. Most lights don’t have built-in low voltage protection and will discharge below 2.8V but typically have low voltage warning (light starts flashing) that kicks in around 2.8-3.0 volts. As for charging, as long as it’s a quality charger it doesn’t matter if the battery is protected or unprotected. The charger will safely charge the battery to the appropriate voltage and stop.
Y’all need to do more long night rides. I’ve seen LVW on S2+s, Convoy C8s, a Thorfire TK15S, and probably others I can’t think of right now. Now that the days are getting shorter, I’m looking forward to a C8F “runtime test” on my bike.
I prefer switching in my spare batteries than go the LVW route when doing night rides. I can't let all my batteries look pretty sitting on the shelf, I want to use them too!
I switch batteries, I but I don’t bike with a DMM, so LVW tells me when to switch.
I once managed to get LVW on a Convoy S2. A 3*7135 S2. So yeah, battery drain can sneak up on you.