Thermometer for measuring cell temperature.

[march.brown]

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I was wondering the best way to check the temperature of cells, chargers and torches because it is difficult to explain to someone on CPF that the cells are quite warm (for example) ... I had a look on Ebay and found some very expensive infra-red thermometers and a cheaper one.

I found an "Infrared Digital Thermometer, Non-contact and wide range" that seems OK.

Measuring range is -4F to +428F or -20C to +220C ... Accuracy is + or - 2.5% ... Resolution is 0.5 degree F or C ... I think that is better than quessing.

The Distance to Spot ratio is 1:1, so it would need to be less than 10mm from the cell, but that's no problem.

In the UK it is post free ... Europe is £1-00 extra and America and Australia is £1-70 extra.

Price is only £8-50.

There are lots of other uses for something like this, so I have sent for one.
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[Russel]

Here is the little one that I use:

Not super accurate, but great for keeping an eye on cell temperature while charging.

 

[march.brown]

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Do you check its accuracy against boiling water ?

Do you check its accuracy at all ?

Just wondering, as I will try the temperature of boiling/simmering water to see what it displays ... I won't go to the trouble of correcting it to the sea level value.

I can then use the difference between the displayed temperature and 100C to work out a correction factor, hopefully.

I don't think a couple of degrees will be that important though for my use.
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[Bapman]

This is the one I use :thumbsup:


http://www.duratrax.com/caraccys/dtxp3100.html


It is reliable and have a resolution of 0,1 C° or F°,

and range from -33 to +220C°(-27 to +428F°):twothumbs

 

[Mr Happy]

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Do you check its accuracy against boiling water ?

Just wondering, as I will try the temperature of boiling/simmering water to see what it displays ... I won't go to the trouble of correcting it to the sea level value.

I can then use the difference between the displayed temperature and 100C to work out a correction factor, hopefully.

No, you can't do that. Infrared thermometers work by measuring infrared radiation and they have an adjustment factor for the emissivity of the surface you point them at (which should normally be a flat, dull, surface). They go berserk if you point them at boiling water (I just tried it), but you should get a value reasonably close to 0°C if you point them at melting ice cubes.

The emissivity adjustment allows for different surface textures (for instance shiny metal is quite different from matt-black paint). The default emissivity will be set at about 95% and this is approximately correct for most surfaces.

Unless you are prepared to go to a lot of trouble it is not worth trying to calibrate such thermometers beyond the default settings. You should normally get a reading accurate to within ±1°C and this is adequate for everyday purposes.

 

[Elliot]

The Duratrax is nice but it's accuracy is about 2% like most inexpensive units. The display shows number to .1 F or C. Two different things.

 

[Russel]

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Do you check its accuracy against boiling water ?

Do you check its accuracy at all ?.

I haven't tried checking the accuracy until today. When I check boiling water I get a fluctuating reading around 80 degrees Celsius. I measured the temperature of a metal thermometer in the fridge and got 36 degrees Fahrenheit. (The little mode button changes back and fourth from C to F) The metal thermometer was reading 38 degrees.

I don't know the accuracy of the metal thermometer, but I can suspect both are reasonably accurate. I use the little infra red thermometer for general battery temperature checks. I works great for that. I'm not trying to take scientific measurements.

 

[Mr Happy]

When I check boiling water I get a fluctuating reading around 80 degrees Celsius.

Steam absorbs IR radiation and so any steam between the object and the thermometer will make the thermometer read too low. Steam and dust are two things you must not have in the air when you are taking IR temperature readings.

 

[Russel]

That makes sense. I was wondering why it would read so low. I find that it works pretty consistently, so when I saw 80 degrees C I laughed a little and disregarded the reading. It's a handy little device, I like that it fits in my pocket.

 

[amigafan2003]

The Duratrax is nice but it's accuracy is about 2%

And?

So, if you took a reading and it showed 67c, that means the true value lies between 65.7c and 68.3c - hardly worth losing sleep over is it?

 

[Elliot]

And?

So, if you took a reading and it showed 67c, that means the true value lies between 65.7c and 68.3c - hardly worth losing sleep over is it?

I don't disagree, I was only posting so people would not buy it thinking it has .1 degree accruacy as posted prior. Actually people use IR to measure body temp. and so many people in the medical profession do need very accurate meters.

 

[march.brown]

What happens if you point it at the side of a plastic kettle that has just boiled ?
That must be pretty close to 100C and there wouldn't be any steam present.
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[vali]

I don't disagree, I was only posting so people would not buy it thinking it has .1 degree accruacy as posted prior. Actually people use IR to measure body temp. and so many people in the medical profession do need very acurate meters.

Yeah, I have a cousin who is a nurse and she said me that they almost never use IR thermometers. She said too that the electronic ones are decent and the best are the old and trusty (and dangerous when broken) mercury ones .

But to check if a cell is "warm" or "hot" I think the IR is more acurate than fingers

 

[Mr Happy]

The Duratrax is nice but it's accuracy is about 2% like most inexpensive units.

And?

So, if you took a reading and it showed 67c, that means the true value lies between 65.7c and 68.3c - hardly worth losing sleep over is it?

Not quite true. A reading of 67°C is 340 K. Accuracy of 2% would then be 340 ± 7 K, or between 60°C and 74°C...:thinking:

However, I have the MicroTemp MT-200, which seems very like the Duratrax, and I usually get readings that seem correct to within a degree or so. (For instance it tells me my room temperature is 70°F right now, and various other thermometers all say 69°F or 70°F.)

 

[Russel]

What happens if you point it at the side of a plastic kettle that has just boiled ?
That must be pretty close to 100C and there wouldn't be any steam present.
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When I did the boiling water test I simply heated a cup of water in the microwave. When I measured the side of the cup I got about the same reading, just a little more stable.

I do have a tea kettle for heating water. I will, just for the fun of it, get some water boiling in it and see what reading I get off of the side below the water level.

 

[45/70]

I bought one of these for detecting which cylinder(s) were missing on air cooled aircraft engines. Everybody made fun of me, suspecting me as being a "gadgeteer", which I am. I ended up checking cylinders, as I and everybody else always had, with my hand, and I'm that way with batteries as well, but it does come in handy for other things.

Dave

 

[Russel]

Well, I tried measuring a tea kettle (chrome plated) while boiling water on the stove and got about 44 degree Celsius. That didn't work very well. So, I figured I might try the other end of the spectrum - ice. I stuck my arm in the freezer and measured the ice cubes and got -11 centigrade. So, I took out an ice cube and held it in my hand until it melted against my skin a little and took a measurement and got a fluctuating reading of about 2 to -2 degrees Celsius.

 

[was.lost.but.now.found]

Yeah, I have a cousin who is a nurse and she said me that they almost never use IR thermometers. She said too that the electronic ones are decent and the best are the old and trusty (and dangerous when broken) mercury ones .

But to check if a cell is "warm" or "hot" I think the IR is more acurate than fingers

My wife's doctor is really old school and still uses the mercury thermometers that come wrapped in paper. I won't tell you what the flashlight he uses to look in patient's mouths looks like.

 

[Bapman]

Sorry , for my mistake:mecry:

The display resolution is 0.1 C° or F°,but the infrared accuracy is ±2%.


http://manuals.hobbico.com/dtx/dtxp3100-manual-v1_1.pdf


Above is the thermometer manual.


Ben

 

[march.brown]

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My infra-red thermometer arrived today and it works well.

Strange that the outside of the white plastic kettle only reads 200F after boiling though ... Should read 212F ... We are only a few hundred feet above sea level ... Fridge and freezer and other assorted thermometers check out OK ... Even the difference between top and bottom shelf of fridge are different ... It will be great for looking for cold-spots in various rooms too.

Just waiting (and waiting) for my new charger to arrive from Hong Kong then I will check some 18650 temperatures before, during and after charging.

For £8-50 including postage, this has to be one of the most useful accessories for the home (and for battery/charger monitoring).
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