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

Well, I believe these lights also lock physically (although I suspect the OTR M3 Pro doesn’t have stop the drain - I may have a faulty light).

However, the question here is not what is “practical” or not for us users, but the “design” of the lights and what they may imply for people that are not always looking to these details and that may “run out of juice” in the middle or nowhere while expecting the lights to have battery.
That is my major concern (along with the potential drain that it takes for the batteries if they go down to 0V).

Ok I think I got some of this, but maybe not all, so bear with me.

I know I am dealing with many variables here, but if I use other batteries and the light behaves the same way (same drain), doesn’t it imply that the flashlight will stop working properly when flashlight reads “2.8V” or less (or the cut-off voltage it works with)?

That’s what I’m “worried” about and the measurements above are just an exercise. Maybe manufacturers can decrease the drain.
I now that the calculation you did is more reliable though.

(I’m sleepy so all of this can make no sense… :person_facepalming: )

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: Battery charge percent

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).

Ok, now I got it! Like I said, yesterday I was sleepy and my brain was not doing the right connections!
So, the drain may not be linear, then the estimated time to drain the battery can be over or underestimated.
Thanks LB :wink:

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 :wink:
Thanks again for the clarification!! :+1:

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 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.

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.