scrutiny on aux led hasn't caught up with proliferation of aux leds

The difference in current consumption between different colors of aux lights is actually noticeable without testing to some degree. I had already gathered that the red aux lights seemed to drain the batteries faster than cyan for example.

It would definitely be nice to have a reference sheet for those concerned about their battery life. My own approach is to check the voltage every time before I put it in my pocket. I also do a physical lockout when I am not actively carrying the light.

I’m OK with bling. A $70 flashlight is 80% bling and 20% functionality if we are totally honest. But the bling needs to be accompanied with understanding and data. Otherwise, it transforms flashlights from a hobby where you make informed decisions about your preferences and priorities to some gross marketing driven smaug-esq pursuit.

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Thinking about it some more, I just realized that a good question to ask is this:

How would you review a flashlight that is designed to stay on ALL THE TIME.

That’s what lights with aux LEDs are. It’s two lights. There’s the main emitter that you apply the traditional set of analysis to that we see over and over again from established reviewers, and there’s also this second emitter that stays on all the time that also requires a pretty thorough analysis that maybe need more thought because it’s not the traditional main emitter analysis because it’s on ALL THE TIME.

@river345, for TS21 I got 12.9 mA on bright button mode.

You only got 1.48 mA? Which generation TS21 is yours?

I notice you measured at 3.6V. My measurement was with a full battery. Could this be why our results are different?

By 3.6V, I mean my power source was set to 3.6V when I measured the current on the LED. Even if I use the max of 4.2V as voltage source, my current reading should be 1.7mA max. So something is up. My TS21 was purchased 2 months ago. It has a orange color LED. Do you have readings for the other modes (low, blinking) to compare?

What other lights do you have to compare brightness with? I have a SP36 BLF 2nd gen with Anduril 2 and orange LED. The indicator light on my TS21 on bright is slightly dimmer than this SP36 on bright.

I’ll check later, but your other numbers seem close enough to Tom E’s. He was the first person to bring attention to Wurkkos TS21’s now infamous parasitic drain.

I measured with battery in light and rear cap off, one probe on battery negative end, other probe on battery tube and got 12.9 mA. Maybe Wurkkos has fixed this?

Your D4K’s number also seem to be pretty high at 3-4 mA? I only have D4V2’s and I was getting about 1-1.9 mA on the 2 lights that I checked.


“This light has a big parasitic drain, moderately high with the switch LED OFF (116 uA) or on low (180 uA), not visible in room light, and excessively, exceedingly high at 13.5 mA with the switch LED on High.”

Usually I directly measure the aux LEDs with a multimeter in series in the µA range.

If the aux LEDs are blinking I measure them with an oscilloscope and a ~100 Ω shunt resistor (which was very easy with this Armytek flashlight because I could use the magnetic charging contacts with a loosened tailcap):

Some great data points thanks! I’m a fan of low, night adapted eyes friendly colours (red, amber, maybe a yellow) not sure how anyone tolerates the blue, green, cyan even at low levels- especially if kept on a shelf/table in a bedroom!

I love the bling and have/had a lot of lights with auxiliaries. Especially lights I mod / build. However nearly all of those lights have the battery removed or at the very least mechanical lockout when not being carried. E-switch lights are treated the same.

I do have 2 exceptions to the rule, a d4 in the garage and an fw3 in the bedroom. Both set to battery indicator on low. These are for blackouts and are easy to find for my family.

My users that I take to work with me have no aux and are tail clicky’s so I don’t have to worry about battery drain.

I can appreciate it’s good to know the power consumption of aux and the same can be said for e-switch lights.

My biggest gripe about auxiliaries would probably be the limited flexibility of brightness levels

Extremely well-written and informative exposition of the issue! I'm so glad to see I'm not the only one concerned about unreasonable levels of drain in blingware.

So far my favorite is the blue lighted switch from Convoy, paired with 5A 4-mode driver. Draws around 1mA at full cell and drops pretty quickly when the cell depletes, which 1) saves capacity and 2) makes a great battery indicator--just by looking at the lighted switch, I could tell the cell voltage within 0.1V accuracy.

Having been away from the flashlight world for over 10 years I feel like I’ve woken up in some sort of dystopia. When I left electronic switches were a gimmick regarded with skepticism, people didn’t want parasitic drain.

To come back and find that electronic switches and additional parasitic drain devices are now the norm is rather disconcerting.

I would agree 100% that reviewers (and manufacturers) should publish current draw data on these auxilliary lights and electronic switches. Perhaps a small amount of parasitic drain could be considered an acceptable trade off for certain features and buyers should be able to make an informed decision on that.

There are different ways that people may want to use Aux and or Button lights, and they require different brightness levels, which will affect runtime. (same is true for main LEDs also)

For example

1. Aux as locator lights, for use with lights that may sit unused for a year at a time.

2. Aux as party lights, to add color patterns to a room, for one night.

3. Aux as emergency Red flashing marker on a disabled vehicle, or carried by a pedestrian or cyclist, to alert traffic.

Each of those applications will benefit from different brightness levels, and different battery recharging intervals.

I think its great that people are sharing parasitic drain info, so we can better understand how to make realistic use of Aux lights.

I get it. High aux levels have their uses, but high aux levels also make LVP and current draw info even more important rather than something that can be brushed off to the side. In fact, if manufacturers are going to make aux lights for the types of uses you listed, I think it’s negligent to not list LVP info and current draw when used with batteries that can be dangerous if over discharged.

I’m not necessarily against high current aux. It’s the combination of high current draw, lack of LVP, and lack of info that is crossing the line for me.

fwiw, Anduril 2 recently implemented LVP for Aux… for example, my TS10 lights have Aux LVP…

I dont expect manufacturers to tell me how long the Aux will last on various modes… Im glad there are people here that share parasitic drain measurements.

Same for CRI R9… manufacturers dont offer that info, but people here share their independent measurements.

Same for PWM and Flicker data, not always available from manufacturers nor reviewers… but again, there are people here who share that info.
btw, that is Opple data… the tool is on sale on Aliex… very helpful for comparing Tint duv also:

I dont expect reviewers to provide info they dont have equipment to measure, but Im glad there are people here who share additional details.

80–20. Yes I am also very in, but i feel like you are being just a bit dramatic (I tried to think of a different word)

cmon…you really feel that way?

edit: For what it is worth I DO agree that at this point it should be treated as a 2nd flashlight.


He would make such a good review of this. I have no affiliation, but I think he is making some of the best produced content I have ever seen. Talking outside of flashlights too.

I agree. Great combination of high level of technical knowledge, ability to get at what’s important, and great presentation skills.

My gf’s got a Cometa that I gave her as an around-the-house light. For me, well, I call mine My Big Blue Lighthouse for obvious reasons, but for her, it’s always on in a dark room in case the lights go out, and bright enough to find even from a distance. But I bug her to occasionally check and recharge all her lights, Just In Case.

I don’t keep ANY lights “armed” (ie, any cells inside) because of parasitic drain, if they’re not in active rotation. Even low-drain sideswitch lights, I either pull the cell entirely, or if a weirdo cell (overly long, etc.) I’ll stick back in any insulator disc to make sure there’s zero current passing through.

Hell, my DV-S9 diving-light has a mag-slider that draws 10mA and will run down a topped-off 26650 in about 3wks. So I only load it up if/when I intend to use it, and unload it immediately after.

So, it should go without saying that any aux lights, lit switches, any other beacons, should only be active in lights that you’re pretty much babysitting on a nightly basis.

Also to add, analysing that kind of drain isn’t always easy. Clamp-meters don’t measure sub-1mA very well if at all. Hell, most don’t even do DC at all. And wired-in current measurement does in at least a small way add resistance and affects the current itself. And that’s worse at lower current ranges.

Plus, some lights like the TS10 are tube-within-a-tube lights, so I wouldn’t even try measuring currents on those.

Oh yeh, the only lights which have always-on lights are my TS10, GTmicro, and Cometa.

My ’10 and ’micro, I have right here, and it’s easy enough to check battery voltage.

My Cometa is “semi-retired” for now, just because the My Big Blue Lighthouse is way way way too bright for me at night.

Only my MH20 has “beacon mode” (faint blip every few seconds on the sideswitch) which I can activate with a half-press from off. But any use on then off resets that. But that’s a carry-light, not nightstand light, so I rarely use that feature, even though I like it a lot, as it’s implemented perfectly.

Any other lights that have andy1/andy2, again, if I don’t have then in active rotation, then I keep them unloaded.

Maybe if you’re clueless and have nothing better to do with your time, otherwise you could just measure the parasitic drain and then you’ll know whether you’ve got 3 months or 3 years before the aux LEDs will drain the cell.

The OP’s point is that lights with aux LEDs should be scrutinized, i.e. measured.