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

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

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)

those fuses often blow where you can’t see it
anyway any fuse without sand —> return meter any buy something better
Meter without fuse on High range the same, as far as you don’t count traces as fuse

I have no DMM to check it :person_facepalming: I guess I really need to get one that allows me to do all the tests I may need. I don’t work with anything else that needs this type of measurements, just flashlights, so I will check which one is the more suitable for it :wink:

Well, by this time I can throw it very far or I will crack the neighbours windows :smiley: But when Covid leaves, I will surely get a new one and eventually practice throwing this one (although the other functions work).

Thanks for the explanation about the readings. I guess the multimeter is limiting the reads on the flashlight too. I never measured the current draw for the OL Contest, I may do it when I get the DMM.

When I open the MM again I will check the fuse to see that thin wire, thanks for the detail.

Yes, I guess I may have put the probes in the wrong holes, and while trying to measure things without the correct settings :zipper_mouth_face: Perhpas it could have been prevented if the material was better but…it doesn’t matter now. I just need to learn what and how to measure without messing things :student:

Hum… I guess I won’t try that mod/trick as I don’t feel skilled enough to do that (as you may notice :stuck_out_tongue: ). I would up damaging the rest of the functions that are still working and lose it all!
Still, thank you for the tip and I believe that some people may benefit from that!!
I also don’t have spare materials and normally I don’t deal with that kind of products, so wouldn’t be able to make that test!

Actually…now I think I shouldn’t have started this test at all :smiley:

Ahah, did you read my post on the “Why Cu?” thread? :stuck_out_tongue:

Thanks again for your help folks! :+1:

still you can check any fuse with any meter that can read resistance
nearly 0 Ohm fuse OK
no resistance fuse dead
I doubt the meter uses the fuse for voltage readings, but if it does that would be bad design but reveal dead fuse instantly

the meter is so stupid designed you can’t check the fuse without disassembling it with the same meter, would a regular 4 terminal be too much costs or is it to get it smaller?

for current measurements on flashlights you need a clamp meter if you go above 1A as otherwise you always

- lower the current by adding more resistance on DD lights

  • increase current on boost/buck drivers or lower depending if the voltage drops too low

Hum, I just don’t have any other tool measurement tool :zipper_mouth_face:
So I’d need to dismantle the MM , take the fuse out and then measure it with the MM, right? Would it work?

You are right, I was thinking right and saying wrong: I will get a clamp meter !!! Not a DMM :person_facepalming:
That’s what I should have bought from the beginning!

Are there any good suggestions for one? Cheap and effective would be the best in this case :innocent:

The same store were I bought the multimeter has them, but they are more expensive and now I don’t know about their reliability…

I know your gonna think this is a bit strange recommending the same brand name but
the UT210E clamp meter seems like a very decent meter. I purchased one after several members here recommended it.
It’s worked fine in the year or so I have had it.

.
HKJ gave it a thorough test here. Test/review of DMM/Clamp UNI-T UT210E

Its OK, but has its drawbacks compared to more expensive ones
in DC mode you always got to zero out the meter
the calibration is permanent off in DC ranges too low about 5%

after a lot of use and already one internal cleanup a few months ago my meter does not behave well,
seems again internal selector ring makes not good contact, readings are wrong or jump
To be worse lately if I touch it on the case a little on the top are it goes out completely, I suspect the battery contacts to conduct not good
It may need some conductive grease or that makes it even worse, gold plating would help on the selector copper plated steel sping contactsI have it right now open again and try to bend the copper plated spring contacts more

I use it only above 10A DC or measuring heavily PWM-ed Current (which the Benning has problems in Auto range mode)very few times

I got a Benning CM11

  • needs no zero out
    the new meter is only rated 10A DC max.
    but it measures also just a few mA with good precision down to 0.1mA resolution

I agree Lexel it’s a Okay meter and as usual more expensive models will have better accuracy and protection with more features.
Not everyone needs a precise meter though or wants to spend hundreds of dollars. Sometimes a good deal can be had for a very decent meter.
This is just a decent general purpose meter that seems to be okay for hobbyist.
I spent $300 on a fluke 87V years ago and would do it again if it failed for some reason but not everyone will feel as I do and would be fine for what they measure with a $20 meter. It really all depends on if you need it or not and have the cash to spare. But I do like having quality tools that will last and work when ask, it doesn’t feel as though I spent so much when they last for years and years. General speaking spending more money will buy you better more accurate products. That clamp meter Lexel looks like a very nice accurate meter. :+1:

great post!

clear and easy to understand, for a beginner like me

thank you for taking the time to explain the differences in prices and choices

If anyone desires to stay with Fluke, this lower-end Fluke is what I use for uA measurements on my lights. This model was intended for sale in China (why it's cheaper), but you can get it in the states for about $135.

https://www.amazon.com/gp/product/

Not weird at all, I see many people using Uni-T tools, and that was what took me to get this small one. I tought it would be better, though.
Thanks for the suggestion.

I will have to ponder those drawbacks and see which will fit my needs the most. I surely don’t need a super accurate or super expensive clamp meter because of my type of use.
Thanks for the suggestion.

Thanks for the suggestion Terry! It may be a little ($100) above of what I can spend on a measuring tool like this :stuck_out_tongue:
Not being an expert guy or a tester/developer I will be looking to have one with a good compromise between what it can measure and what it costs.

I’ll check your suggestions and other tests from HKJ! :+1: