Most of my lights I lock them out either by unscrewing the tailcap, or the head. Tailcap does not always lock out.

Voltage vs capacity is pretty nonlinear, and even varies by type of cell. Best to go by current, and extrapolate.

Eg, a 1mA drain would be 2400H for a fully-charged 2400mAH cell. So 2400/24 would be 100days, around 3mos.

A 10mA drain (eg, light with magnetic ring/slider) would have only 10days before draining it dry. Etc.

Someone (HJK?) posted graphs of various makes of cells and capacity vs voltage. Some cells peter out at 3.4V and drop like a rock suddenly (ie, are already near 0% at that higher voltage), while others have a gradual taper down to 2.8V or whatever and still have plenty of juice left at 3.4V.

Best it to just get the capacity of the cell and measure current draw of the light.

Yup, LB. It was HKJ: https://lygte-info.dk/info/BatteryChargePercent%20UK.html

MascaratumB, like LB was saying originally, it is best to measure this using a DMM if possible. I have one capable of measuring “uA” while most of the rest can at least measure “mA”. Essentially you remove the tailcap, put the DMM in uA or mA mode, and put the leads in between the battery and the body (replacing the path of the tailcap). This will tell you the rate of drain.

Many times if something active is happening (like a blink) the MCU may be left running at normal speed instead of sleeping. This can have a very high drain. Like 10mA vs 5uA (0.005mA).

MascaratumB wrote:

Thanks gchart! I tried with my Uni-T UT33D multimeter but I guess it doesn’t read such small values. I need to get a decent one or a DMM to make this type of measurement!

Also, as I am not familiar with some of these measurements and concepts (theoretically and empirically) I was relying more on the type of “action/tests” i did above.

Now I see they may not be worth due to the aspects you guys mentioned
Thanks again for the clarification!!

You might give the next setting or two a try (20mA or 200mA). The 2000uA setting is max 2mA. The lights might be max’ing that out. Especially the SF14 being a clicky, the flashlight will try turning on and will likely be using more than 2mA.

Even the M150 will probably be over 2mA. The MCU will try turning on and unless they’re using a really low power mode, it’ll initially be quite a bit over 2mA.

It may be that the current probe fuse has blown on your meter. Easy to do this accidentally by trying to measure something that exceeds the rating (200mA in your case).

Try the 10A probe hole for the positive lead and the 10A setting on the dial, then reduce the setting one step at a time to see the reading.

I think you have to switch the red+ probe lead to the Amp side, far left hole.
Alot of meters have this same feature.

The fuse should be an easy fix if you have a spare fuse—sometimes there is a spare in the case. You will have to open the cover, likely some screws on the back cover to access the battery and fuses.

Then like others have said it’s about got to be the fuse.
You can just jump the fuse to get it working but I wouldn’t try to actually measure current draw with the light full on unprotected like that.
Even a lesser value fuse would work for measuring the parasitic drain.
The red probe lead will have to be in the left side hole though.

Two screws and the rest is up to you.

Take a 9V battery and hold one lead, touch the other lead to one nipple (on the battery, duh), then touch the other nipple with your opposite hand. Ie, use yourself as a resistor. See how much current flows through the meter. You can throttle it by squeezing harder on the leads and lightening up, too.

The SF14 is a tail-clicky, no? So making any connection is essentially turning it on, full blast. The fuse won’t blow, but it’d show overrange “0L” or similar.

The sense resistance at the lowest scale might be too high to even let it get started, dunno.

So… first check the ammeter through a large resistance (multimeg). The “10A” socket is only used at the 10A range, and is unfused. That can make your meter go pouf, but V/Ω/mA should be fused.

I hate to say it but the current measurement part of your meter maybe toast.
That’s a little dissapointing that they obmitted the fuse to save a few cents.
I went back and looked through the owners manual of the Uni-T UT33D and all current measurements are made on the far left red probe hole. Which is the far right hole on the back of the pcb where the fuse should have been. The actual board has been designed to jump the fuse by a added trace. The trace could be cut and a fuse added but if it’s toast there’s no point unless you had one that worked. They had to actually go back to their gerber files and add that trace to jump the fuse and have that new file submitted to the pcb manufacture with new boards being made just to admitt the fuse to save some pennys.
It also says as a warning that if the fuse blows it could still damage the meter.
Well, yours did not have a fuse to start with, so it could be damaged.
.
Reading from page 17 of the manual.
https://f00.psgsm.net/p/840023/UT33BCD_Eng_Manual.pdf

Always leave the black one in “COM”.

According to the front of your meter, the red should be in the left for > 200mA and that port is not not protected by a fuse. For < 200mA use the center port. It is fused. But if you use it for > 200mA (easy to do) you could blow the fuse.

The big bare wire is the current sense shunt for the 10A range and it is certainly okay. It looks like your fuse is intact too? So no blown components.

My guess is that either the wipers of the rotary switch are not making a good contact to complete the circuit, or the Chip On Board (COB) controller is broken. You should be able to inspect the wipers to see if they contact or have a gap.

You should be able to read current with the left or center probe socket, the sensitivity and fusing is the only difference, but try the left with a known low-level current and then work your way on the settings.

I found a clearer pic of the labeling for the probe holes. The red center probe hole does look like it says ma with a 200ma fused.
So I’m assuming that the 3 positions of 2000u, 20m, and 200m probably all are measured with the center hole not to exceed 200ma.
The labeling suggest the far left hole is only for measuring currents on the upper end of less than 10 amps.
Kennybobby also brings up a possibility of the wipers not making good contact. That might be something to check also.
HKJ has alot of good multimeter protection info in this thread.
http://budgetlightforum.com/node/66691

Has anyone checked the drain on the WildTrail BLF (D80) lights? I picked up mine last night and both were dead. I didn’t put them in the bag dead I am sure.

Thanks

MascaratumB wrote:

moderator007 wrote:

I’m not sure, but it looks like your model does measure mico amps. It’s marked 2000u at about 7’oclock on the selector dail. That should be plenty good enough for parasitic drain measurements.

Please see if I am doing something wrong in the images below.
I am trying to measure on a Skilhunt M150 and on a Sofirn SF14.

You forget that uA current scale on a DMM has usually a high internal voltage drop in the DMM if some more current flows,
the flashlight may simply quit in LVP because your reading simply lets it see not enough battery voltage through while the MCU is booting up and draws a few mA for a very short time
a common way to avoid this is first short out the tail then let the MCU settle into sleep mode, then add the DMm probes and disconnect the bridge

or the DMM needs a minimum voltage to do the measurement at all

Usually the best method is to have a very high resolution and do the measurement in a larger mA or A region
your DMM is 2000 counts so it can display in 200mA range only down to 0.1mA and had a quite high error on small amounts due to the +/- digit and base accuracy

for example with my lab DMM I have a resolution in the 10A range of 1uA and in 400mA of 0.0001uA
of course the internal resistance will be very low at 10A and fairly low on 400mA so the voltage drop does not affect the light much

Another thing I noticed with Skilhunt lights is the short output spike when the battery is connected
This may even blow the low current range fuse in the DMM and of course you read then nothing

bikenber73 wrote:

Has anyone checked the drain on the WildTrail BLF (D80) lights? I picked up mine last night and both were dead. I didn’t put them in the bag dead I am sure.

Thanks

BLF D80 has no standby drain as the battery stays disconnected if switched off, if you get them out the drawer dead either the battery is faulty, your kids stole it and played until it went to LVP or you left them turned on by accident

even other BLF drivers with Anduril draw only like 30uA in sleep mode with no indicator LEDs connected

you should use your DMM to check the fuse

MascaratumB wrote:

Ex:
MM on setting “10”
Flashlight w/: 18650 cell (at 3.85V) + Lexel Driver w/ Bistro HD OTSM + 4 Luxeon V
Levels: Moonlight + ONE 7135 + Turbo
Readings: 0.00 > 035 > 3.90

Thanks again and sorry for so many questions

My advise take the DMM and throw it as far as you can, walk 1 meter and try to pick it up at the distance you can trust it
then buy something a little more expensive tested by HKJ
https://lygte-info.dk/info/DMMReviews15.html all look bad, you cant trust UNI-T they cut internals in DMMs older are usually better then they save cost on same model number

any Bistro HD driver should draw 4-5mA in moon, you should be able to read that easily in 200mA range
3.9A the leads plus DMM reduce the current like crazy, Luxeon V x4 should draw more like 15-20A

The fuse will have a tiny wire inside going from one end to the other—it could be the size of a hair so you might need a lens to see it. But if it has blown then the wire will be broken or melted.

If the flashlight or whatever is being measured has a high in-rush current during turn-on, then that could blow the fuse. These sort of nuisance blows are common until you get experienced with measuring current and how to avoid such situations. So buy a pack of 5 fuses to have some spares.

In a pinch, you could use a piece of aluminum foil wrapped around the fuse to make an emergency repair. But understand that you will have no protection against an accidental over-current. But if you had a known low current situation then you could use this trick to make a measurement to prove that your meter is functionally okay. This is an advanced trick that i can’t really explain, someone would need to show you how to do this, and it could really damage your meter if the current was too high for the range setting. If you have any breadboard resistors then you could make a test circuit with limited current and this would be a safer way to check the meter. Good Luck, and avoid the copper (Cu)