pros/cons lights that dim/lights that quit ?

i had a light just 'instantly shut off' :huh: yesterday (jetbeam IBS with a protected trustfire 18650) im not certain i wouldnt prefer a light that dims slowly and i get some warning.:candle:


that has to be better then a light remaining 100% bright and then nothing?


doesnt it?

I prefer the lights that blink a few times around 5%, but otherwise instantly die from 100% output. I don't actually own any, but it sounds great.

Lithium cells can be dangerous if over-discharged. If you are constantly deep-discharging Lithium rechargeable cells in a slowly dimming light, you are increasing the risk of a vent/flame incident. As annoying as it is to be left suddenly in the dark, its better & (generally) safer than a Lithium cell explosion. The counter-argument I suppose would be lights that switch to low current draw modes when Vin drops.

I have a solarforce module that flashes for 3-4 minutes and then cuts off at ~3.3V. Very nice, relatively worry free.

I killed one 17670 by over discharging it... never again.

The best is gentle dimming, for some reason all those strobe modes are really irritating. As a matter of efficiency its probably better as you can drain the battery to the bottom with direct drive after regulation ends. You also have the option switch out batteries if you can.

Sudden offs are really disheartening...

my jet 1 proV3 is the light that taught me to carry a backup,, Instant darkness isn't cool

waddup said:

i had a light just 'instantly shut off' :huh: yesterday (jetbeam IBS with a protected trustfire 18650) im not certain i wouldnt prefer a light that dims slowly and i get some warning.:candle:


that has to be better then a light remaining 100% bright and then nothing?


doesnt it?

Click to expand...

My preference is for a light that gives some warning before shutting off.

A lot of the drop-ins that I've modded use the driver from the L-Mini II, which has voltage protection.
When the voltage gets too low, it drops down to low to let you know it's time to change and/or charge the battery.

I also have some other drivers that will blink when the voltage is getting low.

Echoing what some others have said, some kind of a warning is nice. Regulated, but with a low voltage warning of sorts, whether that's some flashing, or a noticeable decline in brightness.

My favorite two edc lights both drop levels before dying
When my U2 gets to level 4 I know I have around 20 mins before the protection circuit kicks in

I haven't really run the novatac flat enough but when high is no brighter than the secondary level (approximate 45lumens) I know it's time to feed it a new battery

I have been stuck in the dark by a pila glx3r at an alarm response
Glad I had my 6p backup with me

these days i always have my Primary fed Surefire T1A hanging around my neck, which will happily provide light in the event my primary EDC light dies.
it is also great for checking the street directory without blinding me, and staggering to the toilet at night without destroying my night vision

If your Jetbeam cuts out when powered by a Li-Ion, it means you're triggering the protective circuit on the battery, which means you're over-discharging it. General rule of thumb, you should not let a Li-Ion fall below 3.6 volts (the protection kicks in at ~3.2 volts, which means you haven't checked it in a while).

If a light turning off abruptly is not acceptable for your application, either carry spares or use some other power source than Li-Ions.

StarHalo said:

If your Jetbeam cuts out when powered by a Li-Ion, it means you're triggering the protective circuit on the battery, which means you're over-discharging it. General rule of thumb, you should not let a Li-Ion fall below 3.6 volts (the protection kicks in at ~3.2 volts, which means you haven't checked it in a while).

If a light turning off abruptly is not acceptable for your application, either carry spares or use some other power source than Li-Ions.

Click to expand...

This.

Some lights will achieve perfect regulation even on CR123's and just quit when there's nothing left without warning. But very, very, few lights are like that, most have some warning when using primaries. When you use protected Li-ions, the protection circuit kicks in before any low voltage warning can be triggered on the flashlight side, unless it's a very smart flashlight like the Ra that detect and monitor the status of the battery, which AFAIK should give some warning.

Unfortunately this isn't always the case. The protection circuit isn't always triggered when the battery is discharged at a very low rate.

At those times dimming is not very noticeable, and a flashing indicator will draw attention far faster. I think the Ra's have a combination. It's odd, my zebralight would flash on some eneloops and just quit on others. The type of batteries must also have something to do with it, depending on the light.

I have never let my torch batteries get so low that they are switched off by a protection circuit.

When I started using 18650 cells , I made the decision to refresh the cells sooner , rather than when they were low ... In my case this means checking the cell voltages when I think the torch has had sufficient use to warrant a new battery ... I always seem to overestimate the useage of the torch ... I find that the voltage is always at least 3.8 volts which means that there is at least 40% capacity (one hour on high) still left ... If I know that I am going to go near the capacity of the 18650 (2hr 30min on high in my Solarforce) , I would put a fully charged battery in and carry another ... But I always carry my two bunches of keys with iTP A3s attatched plus an iTP A2 clipped in a pocket.

It is so easy to check the Li-Ion battery voltage that I would hope that it would become second nature to most torch users ... My Solarforce L2 weighs 157.5 grams complete with a 18650 protected cell ... If I was going to need full power for a longer time than 2 hours and 30 minutes , I would consider taking two L2 torches ... Two torches and two spare batteries would give continuous full power for ten hours ... Luckily , my dogwalking routes are never much more than about one hour ... Depending on how much time my torch spends on the high mode , I find that I can get several walkies per charge.

You have to plan for all possible contingencies , hence my two keyring torches and my EDC.
.

Had a light running on a couple of 18650s die on me while using it at work. Pulled out my back-up light and finished up what I was doing. Since then, I mainly stick with primaries.

march.brown said:

You have to plan for all possible contingencies , hence my two keyring torches and my EDC.

Click to expand...

Yep, that's also why I have two EDC lights on my belt. Both are regulated lights but my primary light is very bright and thus it does not last as long on a freshly charged set of batteries. My backup light has an extremely underdriven LED in it and thus it has a very long burn time while remaining very cool. It's not anywhere near as bright as my primary light, but it's plenty bright enough for most of my tasks. In an emergency when I need to use my backup light, I find that having a long burn time is much more important than lots of light output.

The reason I like the idea of Carrying my MiNi AA when using my other bigger lights with Lithium protected batteries.:thumbsup:

Not much to add here other than I now try to use lights that are right for the task (lower level/longer running) rather than the barn burner all the time.

For me, I like the level drop that my Ra offers in combination with the long running level 1 Eiger I have as a primary light(The Eiger dims over time). If I need more light than the Eiger, the Ra fills the gap. If that's not enough. I still carry the Ra and the Eiger and simply add the bigger light I need. My backups to these backups comes in the form of a spare eneloop AAA for the peak, which simply fits on my keychain.

So to answer your question (finally!), I don't like surprises and prefer some sort of warning.

Like others responding I would also like a bit of warning -- even if it's only a minute. The other day I was mucking about with a Maratac AAA powered by a NiMH cell when it went to black on me in about the time it would take to let out a good sigh. It's certainly not a deal killer for me but it does mean that one must always be prepared for it...

i use unprotected li ion in 4 lights, from 3 to 6 cells per light, if it wasn't for dimming i would kill all my cells by now,
my l900 starts blinking when batteries get low (unprotected) so i know when to change them.
i don't like sudden shut off thing, i'd like to know that my cells are low, so i can replace them and not to get caught in a dark with a dead light.

I like lights that kick down to low to warn you. You don't wind up in the dark and it gives you notice that you should change the batteries soon. My Surefire A2 does that too, it drops to a low-ican mode that gives off a weak yellow light along with the low LEDs. My L4 flickers when the batteries are getting low which is a good warning too. I always have a backup light and batteries nearby if they aren't on me.

Since I use flashlight as a headlight I only will use one that gives warning preferably with a dim mode. Right now I use a Fenix L2D which when I use in Turbo Mode will switch to Dim mode near the end of battery life. This is still enough light for me to be seen and will give enough light to see the road in total darkness when there are no street lights, so I can pull over and change battery.