Test leads for your Multimeter

Well I went out today and got me some MM plugs and some heavier wire to make some test leads ..

We all know that thinner and lower quality leads don't handle high AMPs well , don't we ? [ well you do now ] , I've mentioned it often ...

Anyhow , I got some thicker wire = lower resistance with higher AMPs ..

Wow , the first light I had to test was my L2 with the Manafont 3 mode XM-L in it [ of course ]

Previously it had tested at 3.8A , hmmm , do you want to know how it tested with the new leads ? really ??

5A so far , and that's with a not fully charged Sanyo 2600 , 5 FN amps , thats just crazy ...

Im just wondering what the switch [ clicky ] does , does it add resistance there by lowering current ?

Something to test ...

I just tested again with another MM , and it went a little over 5A ....

Crazy stuff !

Here you can see the difference - Old VS new ... thats 4 to 5 times the size internally ...

Here are the test leads complete

Hmmm , interesting idea ? No , did this to make it easier to get to the neg end of the battery in the body ... [ I like it ] easy to hold ..

Also makes it harder to short ... You have to like that

Here you can see how easy it is

Solarforce 3 mode XM-L pulling just over 2A ......

Manafont 3 mode XM-L drop in pulling 5.44A just moments after the picture was taken it went 5.56A

Still testing : Trustfire TR003 charger

I have to say thicker and shorter wires are a must if you want to read true AMP's in a high current situation .. The thiner wires are ok for testing voltage etc , but once you go over 1A current , you really need to go with higher performance wires [ leads ] ...

And I have been lazy myself in going out and getting [ making ] some high performance test leads [ shame on me ]

From a previous high of 3.8A , to 5.56A with the new leads , that's simply a massive difference , in lower performance applications the difference might be 5 to 10% , but in really high current applications , you need some serious test leads or you limiting what you can measure ...

crazy difference , gotta see what id does through the switch. even with the smaller wire just for comparison.

I have three Multimetres.

Two of them are same brand, but I swap both with Thick wire.

Tested from DRY, first MM is about 5A the other is about 4.2A

Posted some pictures ....

Hopefully helpful ...

I second this. Just to get the effect of the switch out of the way. Please make current tests with the switch included in the circuit.

The switch does add some resistance. The DMM does also add some resistance, even with short and heavy gauge test leads. I.e. if you include both the switch and the DMM in the circuit you will always get to low a reading.

With only the DMM the reading might be either too low or high, depending on DMM+leads and switch.

The current will also depend on the battery, on a freshly charged battery you will get somewhere between 3.4 and 3.8 volt at 5 ampere, depending on manufacturer and protection circuit. Some curves can be see in my overload current trip test.

I did post some measurements of DMM, leads and switches, see post #21 in this thread.

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.

A 110cm 18 AWG wire is about 22 mOhm, but you have to add probe resistance and connection resistance.

With the switch in the circuit I measured some 3.15A , with out switch I got 4.86A [ Stock L2 switch - pre 2011 ]

Im going to try one of the L2T switches next ...

L2T Switch [ clicky ] 3.47A ....

Ill try a 2011 L2 switch next ...

Wowsa = 3.8A with a stock 2011 L2 switch

Useful info from all of you.
Do I only need to replace the wires or the connectors/probes too?

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.

With the switch in the circuit I measured some 3.15A , with out switch I got 4.86A [ Stock L2 switch - pre 2011 ]

Im going to try one of the L2T switches next ...

L2T Switch [ clicky ] 3.47A ....

Ill try a 2011 L2 switch next ...

Wowsa = 3.8A with a stock 2011 L2 switch

WHAT DOES ALL THIS MEAN Old4570? Brighter light?

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.

Brighter ? I was going to light box it after recharging the battery ..

I would expect massive heat sag [ thought the emitter has been potted [ of sorts ] ]

But I will come back with some lightbox figures ...

Mainly it was to highlight the limitations of stock MM Leads , and how they would limit accurately measuring high current ...

Often people notice how current and output dont match , well this is why ...

Nasty nasty variables ... [ The leads being just one variable ] [ Clicky switches being another variable ] [ Batteries and I could go on ]

But didnt that Sanyo 2600 do well , 5.56A ......

Im tempted to buy more ....

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. :)

Isn’t the Kelvin 4 wire method fairly easy to set up?

Warm start ...

Pre 2011 L2 switch Warm start about 950L

L2T switch is about 1050L Warm start

L2 2011 switch , about 1150L warm start

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 ,

Mitro & Old, thats why i always post est OTF lumens in addition to current figs. More info is better than no info. :slight_smile:

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!

More multi meters out there than you can shake a stick at ..

What you want is a MM that can read up to 10A [ 10 amps ]


But how cheap ?

I would recommend at least a $10 budget ..