I did do some measurements with switches in the circuit. I found that for most switches, esp my TR-1200 type (aka Sky Ray 3800 triple XM-L), DRY switches passes the most current. In fact with those switches in the circuit, they rare drop the current....i think it's only about 0.2A for ~ 4A, 3-cell system.
So no way my 110cm 18awg probes can be any where near the resistance of the switches. They drop too much current. For eg, just 2 minutes ago i measured 1.8A with my 4 inches ones, and 1.3A for the 110cm ones.
DMM + leads and tailcap resistance should be equal, in this case you get the right value. Are you able to measure these? These are very small resistances, and hard to measure.
If the tailcap has 100mohm, and you decrease your dmm resistance with thick leads for example to 30mohm, you will measure much more current.
At these levels, not really....totally unappreciable by the naked eye. On the meter you might get a bit, but then with P60s the output sag due to heat is tremendous, so in reality it's really nothing.
Great work. The fact is that "tailcap readings" don't really exist because we aren't measuring though the tailcap. :) I think of current measurements as the maximum current you could get through the light with ideal conditions (which we never have). We can't reasonably match the resistance of every switch we test, nor it it practical to tap in somewhere upstream, so I just think of it as "What current would I get if the tailcap was a 1" piece of 8ga wire?"
It takes way to much work to dial it in to anything resembling accuracy, so we just have to look at the range of readings from different users and average it out.
I would like a setup to measure low resistance, but I'm just not that motivated. :)
But here is the rub , the higher the initial start , the faster the output sags ... In fact it takes about 30 seconds to go from 1150 to 950 and the sag continues at a steady pace ..
If you start at 950 , it takes 30 seconds or so to get down to 870 , and after a minute your doing 840ish ....
So if you went with the higher current tailswitch , the output after a minute would be close , and possibly worse for the higher current one as it would be generating more heat ,
I thank you all for the excellent explanations of the readings from the Digital MM. I am basically electrically challenged. The information provided here helps me understand things much better!
I had something similar to start with , but its accuracy was horrible over 1A , it went into the trash ...
I then got the one pictured , and its been real good ..[ OP ]
But remember , the LEADS are cheap , and accurate measurement over 1A ? , I have some quality leads but even they are limited ...
1A is a lot of current , its enough to kill a person , so you may wish to make new leads , especially if you want to measure accurately over 2 or 3 amps ...
You can remove the wires from the leads and solder short stranded 14awg wires to the probes and connectors. You can use bigger wires as long as you can tolerate the stiffness.
That is big. What’s printed on the wire? The first time I did that I was also surprised by the results. My KD C8 read 2.8A 12awg stranded up from 2.1A stock leads.