I was testing some lights today and figured I would mention this to those that have one of these or want to see the kind of things they can be useful for (they also work great for diy colloidal silver among other things as well).
I use a current shunt for testing tailcap currents. I have tried the clamp meter and while the readings are good I find it a pain to use and you still have to use a shunt anyways in order for it to work.
I figure cut out the middle man, I find using the shunt directly to measure current to be far simpler and easier with only 2 hands.
A shunt works very simply, it is simply a very low ohm resistor. When you pass a current through it there will be a voltage drop according to ohms law. If you measure this voltage drop you can then figure out the current. This is the same thing that happens inside your multimeter, just on a much smaller scale.
You can just connect your DMM to the shunt directly but it will be impossible to get consistent readings, so soldering some “signal wires” to the shunt is much better and easier.
The issues for most is figuring out how to make/buy a shunt for what we need. It turns out it is really VERY simple. Just got to home depot and buy yourself 6 inches of 14 gauge solid core wire, generally used for household wiring. The guy just gave it to me for free since it was so small.
This is your shunt, the only thing you need to figure out now is how far apart to connect your signal wires in order to get a voltage drop that equals 1mv per amp.
In order to illustrate what I am talking about here are some pictures of mine:
SkyRay King version:
Now you can calculate the exact length you need with outline resistance calculators, and they are quite close when I tried it in the real world but it needed some fine tuning, mostly due to the difference in the solder resistance.
So the far easier method is to simple connect the shunt to the power supply and feed say 1A into the shunt (or 10A if your leads can handle that, mine can so thats what I used).
Then you will simply move the wires closer or further apart until the multimeter is reading 1mv with 1A flowing through the wire (or10mv for 10A if you did it that way).
You will have to solder the wire in place a few times and it is easiest to simple heat the solder and move the wire up or down the shunt with the tip of the iron. Once you get it right though it is very accurate and simple.
I simply put some alligator clips on the signal wires and connect them to my multimeter leads when taking current readings. This gives me 2 hands free to hold the shunt in place, and you need both of them.
It is also nice since you do not have to worry about shorting out something due to the meter being in current reading mode and/or blowing your meter / fuse.
This 14awg shunt is good for hundreds of amps should you desire to measure that high.
You can also use a regulated flashlight that will be unaffected by voltage drop in the wires to calibrate it. Simple measure the current with your meter directly and then with the shunt and adjust till they match. For example a 105C could be used for this as long as your cell was charged enough to maintain the full output through the meter wires.