Testing Amperage on a Flashlight

I did test it on my Astrolux S41s with an unprotected 18350 rated at 10A 1000mAh and still got no reading or light from the 4 emitters. My Convoy S2+ is a triple and my stock C8. (which won’t be stock for long).

I think that Kame Sennin might be right and that the DMM may be shot. At least the 10a circuit. The rest should function as normal.

Did you try tapping one of the leads a couple of times to make sure the light switches to a higher output mode? If you are starting in moonlight mode, current may be too small for the DMM to register when it’s set to 10A mode.

All my lights have switches in the tail cap. I have to take the tail cap off to get a reading so idk what to do. This is frustrating me cause I really want a reading before I start my next build.

can you make a video so we maybe see what's wrong?

For what we can see now your multimeter doesn't work on 10A caliber.

The only thing you can do is to find something else :

  • Either buy an other one but be carefull that most cheap ones are not very good at it and introduce a noticable voltage drop
  • Buy a low R measure shunt and use it with you multimeter set on mV caliber

Exemple : This shunt will give your multimeter an 75mV reading at 20A, the good thing is that at 4A it will drop only 15mV the bad one is that you need your multimeter to be accurate enough with such low voltage.

There is always a trade-off to be done between how many mV you can measure and how many you are ready to lose in voltage drop .

Only issue is, how do I post a video onto here?

I think you have to post the video on Youtube, then on BLF you pick "insert video" and input the video's URL.

Maybe you have your meter on the wrong setting—in this video he shows when checking continuity (wrong for amperage) he gets a 1 on his screen


Lmao, I’ve watched that video 5 times and never picked up on how he got the “1” reading! Basically my meter can’t read over 10 amps and all my flashlights are over 10 amps.

All your lights are 1 mode —seems like you could read the lower modes


Your stock C8 draws over 10 Amps???

If the firmware on your lights allow you to change mode groups, you could try setting them up to start on lower modes. Preferably something higher than moonlight, maybe a low of 5% that way you start in a mode that’s within you meter’s capability but enough that you would notice the light turning on.

Pretty hard to measure 10+ amps with factory long leads

At the end of the day it’s all pretty irrelevant as a standard multi-meter is not going to read higher amperages true anyway. The clamp meter is what works here. The UNI-T UT210-E like we bought in the group buy is the way to go. A lot of us here bought this meter so we’d all be on the same page in current draw readings. It can do up to 100A, which at first I thought was pretty ludicrous, but I’m finding these days that I need that… :wink:

UNI-T UT210-E at New Egg for $34.88

With a clamp meter, you simply run a reasonably thick wire from the tube to the rear of the cell to make continuity and use the clamp around the wire to read the current. Break contact with the wire to shift modes, the wire is your temporary switch. :wink: