Learning how to take light measurements with a DMM

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s1mp13m4n
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Learning how to take light measurements with a DMM

Hello all you wonderful folks.  I see posts where people are measuring draw, tailcap measurements, figuring out runtimes, etc.  I want to learn to do this stuff on my own lights.  I have a meter and want to learn what to test and how to test to get the measurements that you talk about on this forum.  Thank you for the help with this.  Smile

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Don
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This article is very good. Like I've often said, the Other Place is full of useful information, pity about the attitude.

http://www.candlepowerforums.com/vb/showthread.php?236906-Simple-guide-t...

 

That should cover most things. Any problems, let us know and we'll be able to add to it as required.

 

The numbers from my light tests are always to be found here.

https://spreadsheets.google.com/ccc?key=0ApkFM37n_QnRdDU5MDNzOURjYllmZHI...

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Thank you very much for the help.  I am off to CPF to read and play.  This will be fun.  I am going to use the light that Foy sent to me for learning. 

 

This is interesting reading, thanks again.  I will play and then post what I find and see what you think....that way I can learn from the results of my own light.

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Don
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s1mp13m4n wrote:

This is interesting reading, thanks again.  I will play and then post what I find and see what you think....that way I can learn from the results of my own light.

 

Best way to do it. It is always cheaper to learn from the mistakes of others than to make your own. Believe me on this. I learned the expensive way.....

 

The numbers from my light tests are always to be found here.

https://spreadsheets.google.com/ccc?key=0ApkFM37n_QnRdDU5MDNzOURjYllmZHI...

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I am using this article to teach me: http://www.candlepowerforums.com/vb/showthread.php?236906-Simple-guide-t...

Light:

Solarforce L2P host

5 mode XM-L T6 drop-in (not sure which model it is)

Trustfire 18650 flame cell 2400Mah @ 4.04Volts

Now doing a current consumption test I get these results (the first test in the article):

I get nothing at all, the meter reads 0.00, what is going on? My test leads are in the 10A unfused and com slots. I am using the scale for A and tried 20m and 200m in the A scale.

 

TailCap:

0.3 ohms meter set to 200ohm scale (lowest it has)

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brted
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Make sure the DMM is switched to the 10A range. With the tailcap off of the light, touch the black lead to the negative end of the battery and the red lead to the bare threads of the light (anodizing doesn't conduct electricity, so you have to touch bare metal). The DMM will complete the circuit instead of the switch. The positive end of the battery should still be in the light touching the spring in the head, just like it usually does.

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Also to note, you will be needing to cycle the modes by taking the DMM lead off of contact for a moment, then back on.

One of the things I've noticed with my fairly expensive meter, is that if you accidentally select the lower current bracket on the DMM, then it will do some current limiting to the driver. Hence, the "set it to 10 A" is good advice if you want real readings.

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OK my leads are red in the 10A unfused slot, black in the Com slot, DMM is set to the 10A scale.  Black lead is at back of battery in the light and I have plenty shiny metal on the treads for red lead, still get nothing.  Smile  Could the meter be fried?  It has a funny smell to it yet it will read battery voltage and to the tailcap test.  It is a $12 autoparts store meter.

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agenthex
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If your meter is kinda crappy, the funny smell might be from the lack of a fuse, but I'd be more worried about the battery if you put it in backwards.

Reading this makes you smarter: http://lesswrong.com/

s1mp13m4n
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The battery in the flashlight is in the right way, the meter was taken apart and it is powered by a 9v which goes in one way and it does have a fuse in it.  The fuse is good, but guess what, the three ports where you put the leads in from the inside are burnt looking, smell bad, and have a corrosion white look to them.  I think I fried the DMM.  Sad  I did not use the 10A setting at first, so it was my fault.  I used what they said in the article not knowing any better.  Who makes a good DMM on a budget?  LOL

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agenthex
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You can't fry a meter if you only put it on the wrong setting with the leads in the right holes, only if you tried to put too much current through the ports.

Just get the cheapass one from harbor freight.

Reading this makes you smarter: http://lesswrong.com/

brted
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Another reason to start off with cheap equipment and move up to more expensive stuff later. Sounds like it may well be fried. You have to use the 10A port and the COM port and switch the DMM to 10A.

I bought this one at Amazon for about $7. The price varies. There are a lot of very similar ones all over. There is also one on eBay for pretty cheap but it is from overseas, so it will take a while.

http://www.amazon.com/Sinometer-DT830B-20-Range-Battery-Tester/dp/B001T3...

This one on eBay is $4. I ordered one, got it, and my puppy chewed it up before I could even try it out. Someone else here liked it though:

http://cgi.ebay.com/LCD-Digital-Multimeter-Voltmeter-Ammeter-Meter-OHM-D...

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Well looks like I need a new DMM.  LOL  Smile  Now I know.  I will have to order the Amazon model, for the price no need to wait for post from China.

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agenthex
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Depends on how much you value your own safety. But hey whatever, I use recycled unprotected 18650's.

Those are the same design (ic inside) as the cheap hb ones.



Another reason to start off with cheap equipment and move up to more expensive stuff later. Sounds like it may well be fried. You have to use the 10A port and the COM port and switch the DMM to 10A.

 

That's not how he burned his, though. He probably tried to measure tail current across a shorted batter or w/ the 400ma port.

Reading this makes you smarter: http://lesswrong.com/

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What about this model here?  Good idea or overkill?

http://www.amazon.com/Equus-3320-Auto-Ranging-Digital-Multimeter/dp/B000...

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agenthex
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I had that in my cart before I found the almost-free HF ones work adequate enough to bother clicking buy on it. I didn't get the other cheapos because they didn't have backlight (and equus doesn't either but it's got the big lcd). Go for it.

Reading this makes you smarter: http://lesswrong.com/

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Now when I get me another meter to replace the one I broke I will keep learning and go from there.  Oh well glad it was a cheap meter and not a $200 Fluke. 

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edc
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I think you didn't set the dmm to 10AA. I did that myself once ( a long time ago)

 

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2nd chance wrote:
Oh well glad it was a cheap meter and not a $200 Fluke.

Not that a Fluke can't be smoked, but you do have to try pretty hard.

I'm amazed at the blunders I've done and my Fluke has survived. (Like leaving it on continuity while I'm checking the output of a power supply.)

For some fun check out www.eevblog.com/2010/05/05/eevblog-84-high-energy-multimeter-destruction/ its about 12 minutes long and is quite entertaining.

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I just got this guy in the mail today:

http://www.amazon.com/Equus-3320-Auto-Ranging-Digital-Multimeter/dp/B000...

I now know what I did wrong before so now I can learn by playing with my Solarforce L2p.  Smile 

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E1320
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Bad news, that meter maxes out at 200ma or .2 amps your XML lights pull over 3 amps or 3000ma. So if you try to measure amperage you will melt that meter or pop the fuse if it has one. I am a mechanic so I bought a Fluke 179 for work and when I popped the fuse it cost $12 dollars for just the fuse. I am sure someone will chime in with a budget meter that will do what you want it to.

I am already visualizing the duct tape over your mouth.

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eeerrr, hmmm that is not good.  Well here I was thinking I was making a good choice.  LOL  Smile  Hmmm, now what?  LOL  Here are the specs from the manual:

 

SPECIFICATIONS
GENERAL SPECIFICATIONS AND FEATURES

3-1⁄2 digit LCD display (maximum reading of 2000); 3 LEDs;
green, yellow and red
Auto Range (ACV, DCV, Ohm, AC mA, and DC mA)
Automatic negative (-) polarity indication
Automatic zero adjustment
Over range indicator (except 10 A function). Displays "OL" on
LCD
Low battery indicator. Displays battery symbol
on LCD
Automatic power shut off (after 15 idle minutes)
Pollution Degree 2
Measuring circuit category II
Operating environment:
Temperature - 32° to 104° F. (0° C to 40° C)
Humidity - Less than 80% relative humidity (non-condensing)
Altitude - up to 6562 ft (2000 meters)
Storage environment:
Temperature - 4° to 140° F (- 20° to 60° C)
Humidity - Less than 90% relative humidity (non-condensing)
Power Supply: Two 1.5V AA batteries
Fuse: 315mA/250V 5X20 mm (Radio Shack, GMA/217
series; #270-1046) fuse
Dimensions:
Height - 5.50 in. (139 mm)
Width - 3.50 in. (89 mm)
Depth - 1.25 in. (32 mm)
Weight (including batteries): approximately 6.3 oz (180 g)
ELECTRICAL SPECIFICATIONS
DC VOLTS
Range Resolution Accuracy
200.0mV 0.1mV
2000V 1mV
20.00V 10mV
200.0V 100mV
600V 1V
3
E
Notes
±(0.8% of Input Resistance: 10MΩ
reading
Overload Protection: 600V DC
+ 5 digits) or AC 600V RMS.
AC VOLTS
Range Resolution Accuracy
2.000V 1mV
20.00V 10mV
200.0V 100mV
600V 1V
Notes
Input Resistance: 10MΩ
±(1.2% of Overload Protection: 600V DC
reading
or AC 600V RMS.
+ 5 digits) Frequency Response:
50Hz - 400Hz
RESISTANCE (OHMS)
Range Resolution Accuracy
200.0Ω 100mΩ
  2000kΩ 1Ω
    20.00kΩ 10Ω
      200.0kΩ 100Ω
        2.000MΩ 1kΩ
          20.00MΩ 10kΩ
Notes
±(1.0% of
Overload Protection: 250V DC
reading
+ 5 digits) or AC RMS.
±(2.0% of
reading
+ 5 digits)
DC AMPS
Range
Resolution Accuracy
Notes
±(1.0% of Overload Protection: Fuse
reading
315mA/250V
200.0mA 100μA
+ 5 digits) Input Voltage Drop: <0.2V.
±(2.0% of Unfused; 15sec maximum
2.000A
1mA
reading
Input Voltage Drop: <0.2V.
*10.00A 10mA
+ 5 digits)
*A waiting period of at least 15 minutes is necessary between
every 15 second testing period.
20.00mA 10μA
AC AMPS
Range
Resolution Accuracy
Notes
20.00mA 10μA
±(1.5% of Overload Protection: Fuse
200.0mA 100μA
reading
315mA/250V
+ 5 digits) Input Voltage Drop: <0.2V.
4
E
BATTERY TEST (LEDs)
When the voltage of the battery being tested is lower than
10% of its rated voltage, the red LED will not light.
Load
Range Resolution Current Accuracy
1.5V 0.001V 10mA
           (approx.)
6V 0.01V 100mA
        (approx.)
9V 0.01V 10mA
        (approx.)
12V 0.01V 200mA
         (approx.)
Notes
Green LED: 1.30V
±0.075V and up.
Yellow LED: 0.94V
±0.075V to 1.29V
±0.075V.
Red LED:0.15V±0.075V
to 0.93V±0.075V
Green LED: 5.22V
±0.3V and up.
Yellow LED: 3.76V
±0.3V to 5.21V±0.3V.
Red LED:0.6V±0.3V to
±(5% of
3.75V±0.3V
reading
+ 5 digits) Green LED: 7.83V
±0.45V and up.
Yellow LED: 5.64V
±0.45V to 7.82V±0.45V.
Red LED:0.9V±0.45V to
5.63V±0.45V
Green LED: 10.44V
±0.6V and up.
Yellow LED: 7.52V
±0.6V to 10.43V±0.6V.
Red LED:1.2V±0.6V to
7.51V±0.6V
DIODE/CONTINUITY TESTS
Function Range Resolution Description
Diode Test 2V
1mV
Test Current:
1±0.6mA
Test Voltage:
Approx. 1.5V
Continuity 200Ω
Test
5
E
0.1Ω
Note
Overload
Protection:
Approx. 120Ω or 250V DC or
AC RMS
less, buzzer
(beeper) will
sound

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E1320
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s1mp13m4n wrote:

eeerrr, hmmm that is not good.  Well here I was thinking I was making a good choice.  LOL  Smile  Hmmm, now what?  LOL  Here are the specs from the manual:

 

OK I think I was wrong I was reading a review that said 200ma max but I see a DC 10A selector in the picture so you should be good . Set the knob to DC10A put the red wire into the one marked DC10A and black to ground and test away.

I am already visualizing the duct tape over your mouth.

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E1320 wrote:

Bad news, that meter maxes out at 200ma or .2 amps your XML lights pull over 3 amps or 3000ma. So if you try to measure amperage you will melt that meter or pop the fuse if it has one. I am a mechanic so I bought a Fluke 179 for work and when I popped the fuse it cost $12 dollars for just the fuse. I am sure someone will chime in with a budget meter that will do what you want it to.



That's for AC current measurements.

added: I replied before I saw your last msg.

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E1320
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That is a really nice meter for $16 bucks I might have to pick one up to leave in my tool bag in my truck. Great find have fun with it.

I am already visualizing the duct tape over your mouth.

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OK sweet, I am glad that I have a quality DMM now.  Smile  I am looking forward to having fun with it and learning. OK here goes:

Solarforce L2p Host

5 mode XM-L drop-in

Trustfrie Flame 18650 cell @ 4.04 volts

Current consumption Test

Low= .083amps

Med= .835amps

Hi   = 1.95amps

 Alright, so now that I have this, what do the numbers tell me about the light?

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E1320
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s1mp13m4n wrote:

OK sweet, I am glad that I have a quality DMM now.  Smile  I am looking forward to having fun with it and learning. OK here goes:

Solarforce L2p Host

5 mode XM-L drop-in

Trustfrie Flame 18650 cell @ 4.04 volts

Current consumption Test

Low= .083amps

Med= .835amps

Hi   = 1.95amps

 Alright, so now that I have this, what do the numbers tell me about the light?

Use this chart and what you know about the emitter to convert to approximate lumens.

http://flashlight-wiki.com/Brightness_Bins

Your Solarforce is an XM-L emitter T-6 bin at 1.95 amps approximately 650 lumens on high.

You might get a higher maximum readings if the battery is freshly charged.There is some lumen loss due to the lens not being 100% transparent and other factors.

I am already visualizing the duct tape over your mouth.

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The light that I got in mail today from Manafont:

Ultrafire 504B host

Ultrafire 3 mode XM-L T6

4.12v 18650 cell

this setup gave me these numbers for power consumption

Low= .05 amps

med= .38 amps

hi= 1.1 amps

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agenthex
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You must have a deadish battery or the worse T6 in existence since that's DD. Or MF total changed their drop-in.

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E1320
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s1mp13m4n wrote:

The light that I got in mail today from Manafont:

Ultrafire 504B host

Ultrafire 3 mode XM-L T6

4.12v 18650 cell

this setup gave me these numbers for power consumption

Low= .05 amps

med= .38 amps

hi= 1.1 amps

I have half a dozen of those drop ins and 4 504Bs and they all pull over 3 amps on high so you have a problem someplace.

Your batteries may not be good, what batteries are you using?

The leads to your DMM may be to thin to accurately measure higher amperage.

There may be resistance issues with the host (dirty threads etc. causing to much resistance measurable in Ohms) but that is doubtful.

Maybe you got a bad drop in, is it brighter then the one Foy sent you?

You should get numbers like this

High 3.4

Medium 1.0

Low .17

Those sound like numbers from an R2 drop maybe they sent you the wrong one.

I am already visualizing the duct tape over your mouth.

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The screw on reflector reads "Super Bright XM-L T6 4.2v" it came in an Ultrafire packaging with no marking on it as to what was inside. I am going to charge that Flame battery that Foy sent me in the Solarforce and try this again.  The new XTAR 18700 cells I ordered will not fit in that Ultrafire 504B host, their diameter is too large....it wants to peel the stickers off the battery. The only other 18650 cells I have came from a guy on CPF who sold me a flashlight that I do not have any longer.  They are Ultrafire 3000Mah cells....the red ones.

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