Reversing the leads will only show as a negative current on your DMM meter , so no ill-effects.
It certainly looks as though you have the meter leads in the right sockets and a 3A current should not blow a 10A fuse.
When you have the tailcap on the torch , can you switch the torch on and off OK ?
With the tailcap removed , when you apply a short-circuit from the torch body to the battery negative , does the torch switch on OK ?
If you use one of your spare 10A fuses as a short-circuit between the torch body and the battery negative , does the torch switch on OK without the fuse blowing ? … If the fuse blows , then either the current is greater than 10A or the fuse is rated lower than 10A.
Well craftsman requires the use of fast-burn fuses…. is this really a necessity? the fuses that I took out are indeed 250V 10A fast burn fuses. Can I just use non-fast burn fuses?
The lights in question that I had used this DMM on indeed function properly (i.e. I can bypass the tailcap with a short and switch modes, tailcaps function properly etc)
However I have not tested the fuse in line with the short, so when I get some fuses I will try that out.
This sounds very strange indeed, the only thing i could think of is that the fuse is rated at 1.0A and the printing looks like 10A, as i’ve had bulbs and fuses that are very hard to read. Also is the fuse actually blown? Maybe the action of changing the fuse can disturb a bad solder joint in the meter which makes connection for a while until the current flowing breaks the dodgy connection and makes things appear like the fuse has blown.
I think the fuses are for CAT rating safety incase one does something stupid or accidental. Two of my old DMM’s dont have a fuse at all on the 10A range. I’ve measured 15A in the past! The leads get warm but the meter handles the power no problem! I would try the slow blow fuse and see if it makes any difference. What i’m trying to say is, replacing the fuse might alter the safety rating slightly if you work with mains electricity, but for flashlight measuring nothing bad will happen at all.
I don't recommend my Ideal DMM. I was just saying it looks like we use the same fuse. When we were doing some electrical work I was getting some funny readings.
I'm currently looking for a DMM that will give reliable tail cap readings w/out spending retail $$ for a Fluke.
Makes sense. But even with this, could the batteries used during tail cap readings provide over 10A? I used some Protected Angelfire “3200mAh” (yeah right) and some salvaged Sanyo UR18650A cells from a laptop battery.
What could cause the light to spike to such a high current?
For very brief duration, absolutely. I would bet they can provide 50 or 100A for somewhere between a few microseconds and a few milliseconds - maybe more…
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Crappy driver design
an intermittent short that only happens when something ‘moves’ to just the right place
The only lights that I have measured are P60 hosts.
PilotPTK;
Crappy driver design;
One of my dropins “was” a three mode XML that I had issues with…
as you can see HERE
Now that it seems to be brighter than ever before, I wonder if this is the culprit… (although the highest reading I got out of it was 1.9A with the craftsman leads)
If you change to a slow blow fuse, or a higher rated fuse, the worst that I would assume could happen is you might fry the DMM. Certainly do NOT remove (and short) the fuse completely though!
My first suspicion is something to do with the driver.
I will however, try a slow-blow fuse once I can get my hands on some.
Maybe because of this, a fast-blowing fuse would be too quick to blow as it would be more sensitive to very brief spikes above 10A. I would think that a slow-blow fuse might not blow on these same occurances. (Correct me if I am wrong)