Test leads for your Multimeter

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old4570
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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 ...

 Always remember , the easiest thing in the world to do , is to expel hot air from your lungs and through some vocal chords ..
The resulting sound may , or may not be worth listening too ….

 

Edited by: old4570 on 12/03/2011 - 01:13
df2dot
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crazy difference , gotta see what id does through the switch. even with the smaller wire just for comparison.

 

Pok
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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

old4570
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Posted some pictures ....  

Hopefully helpful  ...  

 Always remember , the easiest thing in the world to do , is to expel hot air from your lungs and through some vocal chords ..
The resulting sound may , or may not be worth listening too ….

 

Leelou
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df2dot wrote:

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

 

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.

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HKJ
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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.

My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/

2100
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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.

HKJ
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2100 wrote:
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.

 

My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/

old4570
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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 

 Always remember , the easiest thing in the world to do , is to expel hot air from your lungs and through some vocal chords ..
The resulting sound may , or may not be worth listening too ….

 

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

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viffer750
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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.

 

unique engrish language... Smile

 

ri chevy
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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? 

2100
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ri chevy wrote:

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.

old4570
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ri chevy wrote:

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? 

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 .... 

 Always remember , the easiest thing in the world to do , is to expel hot air from your lungs and through some vocal chords ..
The resulting sound may , or may not be worth listening too ….

 

mitro
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Great work. The fact is that "tailcap readings" don't really exist because we aren't measuring though the tailcap. Smile 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. Smile

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

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old4570
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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 , 

 Always remember , the easiest thing in the world to do , is to expel hot air from your lungs and through some vocal chords ..
The resulting sound may , or may not be worth listening too ….

 

2100
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Mitro & Old, thats why i always post est OTF lumens in addition to current figs. More info is better than no info. Smile
ri chevy
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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! 

old4570
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 Always remember , the easiest thing in the world to do , is to expel hot air from your lungs and through some vocal chords ..
The resulting sound may , or may not be worth listening too ….

 

old4570
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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 ...

 Always remember , the easiest thing in the world to do , is to expel hot air from your lungs and through some vocal chords ..
The resulting sound may , or may not be worth listening too ….

 

Leelou
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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.

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Leelou
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http://en.wikipedia.org/wiki/American_wire_gauge 14awg is about 1.6 mm solid wire equivalent in diameter. Use 12awg if you can find soft stranded ones. What size wires did yo use old4570?

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old4570
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Leelou wrote:
http://en.wikipedia.org/wiki/American_wire_gauge 14awg is about 1.6 mm in diameter. Use 12awg if you can find soft stranded ones. What size wires did yo use old4570?

 

Dialcalipers say 3mm 

 Always remember , the easiest thing in the world to do , is to expel hot air from your lungs and through some vocal chords ..
The resulting sound may , or may not be worth listening too ….

 

Leelou
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old4570 wrote:

Dialcalipers say 3mm 

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.

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old4570
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Jaycar 12 Guage 

 Always remember , the easiest thing in the world to do , is to expel hot air from your lungs and through some vocal chords ..
The resulting sound may , or may not be worth listening too ….

 

Oxy Moron
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Excellent thread.

Quick question for the experts: are there any commercially available DMM leads you'd recommend? I have these from DX, but apparently the new batch is useless for any high current applications and when I am getting people started with flashlights and explain battery safety, I'd rather be able to give them something that looks professional, even if it's inferior to DIY leads.

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gorann wrote:

What are 14awg wires?

The closest from standard metric sizes (and quite suitable for measuring flashlight tail currents) is 2.5mm2 stranded (pletenica) wire.

Make your own leads, using banana plugs that you can buy locally, and 0.5m (or less) of that wire per lead.

 

EDIT: When choosing a DMM, look for standard 4mm connection ports. not the thinner ones (2.5mm, I think they are).

mitro
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Can anyone point me towards good (cheap) banana plugs that I can build my own with. I have ones that are made for audio stuff, but they screw together and pinch the wire for the connection. There's no good way to solder them (even though I have) and there is way too much exposed metal just asking for a short circuit. Old's look pretty good, are there other options?

Wire is easy enough and I have gator clips I like, I'm just missing suitable plugs.

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gorann wrote:

Uhm, its a problem that im very technicaly unsavvy.

These banana plugs are only for 4mm ports? (regarding MMs, I have set a price limit to cca 12$).

Leads are the parts which go in the multimeter or what?

How will I conect wires to multimeter?  And what should I put on the end of the wires (when wire is going  out of the multimeter, on its end...)

A measuring lead is a length of wire with suitable plugs on both ends. I suggest plugs of the "4mm banana" type, as they are the most standard in our part of the world and you connect them to most DMMs directly and use the "bananas" on the other end as simple probes, or fit some special attachments to them (pointed probes, alligator clips, whatever).

This is just for the picture, I'm sure you can buy them locally:

http://www.made-in-china.com/showroom/huanleijiangxian/product-detailJqxnDrTdJHhO/China-4mm-Banana-Plugs-Set-Four.html

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