Are my estimations correct? (parasitic drain in different lights)

Just tried what you mentioned with 4 different lights (Skilhunt M150 and M200, OTR M3 Pro, and Sofirn SF14).
I tried all 4 on the three settings (2000, 200 and 20) and the results are always “Zeros” :zipper_mouth_face:

I guess the multimeter is damaged :zipper_mouth_face:
I went to look for an older post I did and it was working… not now .

So I will not have results with this :frowning: and this function is ruined…

Thanks again for your support on this and for your explanations!!!

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.

That’s probably what happened :zipper_mouth_face: And…it is probably not an easy fix, is it? :weary:

I tried what you suggested, but only zeros again. It was the fuse, most probably.
Thanks for the suggestion!

I think you have to switch the red+ probe lead to the Amp side, far left hole. :+1:
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.

I tried it on both, middle and left, and on the different settings above. Nothing works… Sometimes the - appears, but it disappears then…
I believe it is “poof” :person_facepalming:

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.

Given the current situation I may have to wait some weeks to take it to the store where I bought it and check if they have fuses there. It is a small shop, but the guy seems savy on this.

Stupid fuse … or stupid me :rage:
Now I won’t be able to entertain myself measuring this :person_facepalming:

Thanks for the help folks :+1:

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.

Can I take some conclusions through this comparison?
Mine (left) is different. It only has 1 fuse, and it is not ceramic… :zipper_mouth_face:

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. :person_facepalming:
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.

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.

Thanks for checking it!!
I was a bit :o when I noticed that mine didn’t have the fuse…
I will have to go to the store where I bought it and ask the seller about this.

Not knowing how this things works completely, I may have screwed up the only fuse it has, so my fault is there too.
However, it seems that the other fuse could have been useful avoid some damage, no?…

The rest of the functions seem to work well, so far. I tested LEDs and battery voltage. So far they seem to be working except this… :weary:

I will have to get a DMM as it seems more appropriate to the type of measurements we do concerning flashlights.

Thanks again folks for your help and for checking this stuff! I still have a lot to learn…

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.

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

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

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

Well, as I am not familiar with the looks of the fuses, I am not sure. It doesn’t seem to be “blown”, it is not “dark” or anything like that. (Looking at the images provided by HKJ, it doesn’t seem to abnormal!)

Picking your suggestions I dismantled the MM again and checked those contacts. All seemed well.
However I picked a piece of kitchen paper and cleaned the board where the button rotates. Also, one of the metal spheres inside was not on its place (over the spring). I am not sure if it was me that took it out when pulling the round button or it if it was already out.

What happens now is that when using the RED probe on the left side (10A max / Unfused; Max 10 Sec each 15 min) I managed to get some readings on different lights. While using the RED probe in the middle (200mA; Fused) doesn’t get any reading in any of the settings.

So, using the probe on the left side, and on the different settings, the lights with tailclicky switches started to turn ON and a change modes (when I lift the probe up and down in the + contact).

On the Skilhunt M150, with the light OFF, there was no reading in any setting, so I clicked the switch to turn it ON and it started getting readings. I also locked it up with the switch blinking red, but I couldn’t get any reading of it.

In this specific case why do I have absence of a reading?
Due to the probe being on the left side?
Due to the MM screen/specs?
Due to a very low drain while locked?

At the same time, how can I read the other numbers?
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 :zipper_mouth_face:

you should use your DMM to check the fuse

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