CHT measurement via electronic meters

[mousewheels]

Electronic meters can be very inexpensive. Also they can offer attractive functionality. Later in the thread some fully featured meters will be looked at. But at the beginning, its all about getting instrumented at low cost.

09/04/2009 updated - added specs for the meters. Be careful with the max temp rating, optional probes may be required, the probe insulation can't take that high heat. Where available, the factory supplied probe rating will be included. For CHT use, factory is fine.

1st up - rock bottom CHT Total Cost - $11.88 w/shipping
Title: Digital LCD Type K Thermometer Single Input Pro TM 902C
eBay item: 180402989515
Thermocouple type: 'K'
Power: 9V 6F22 cell battery
Size: 11(L) 7 (W) 2.3(H)cm
Weight: 155g
Temperature Range: -50 degrees to 750 degrees C (- 58 to 1382F) of the TP01 Temperature Probe
Accuracy: +/- 0.75%
Resolution: 1 C
3 1/2 digital LCD display with max reading of 1999

Downsides: Short cable, only reads in degrees C

To keep a low budget, the included probe was used to make a spark plug ring mount. JB weld is good for 450 degrees, 500 intermittent. Their website says it is non-electrically conductive. Scrap of copper close match to plug gasket thickness. Buying a 14mm bit out of scope. 3/8" drill, ream out to 1/2, file to fit.


Finished ring lug and meter. Inset shows thermocouple tied to riing via 'Nomex' thread (non-flammable, good for 200C+) prior to glue & heatshrink tubing


On scooter, dropped into drink holder - measuring 179C. Conversion: F = C * 9/5 + 32 . Quicker way to do it in you head is F = (2 * C) - 0.1* (2 * C) + 32. With minor approximation we've got (2 * 180) ==> 360 - 36 ==> 324 + 32 ==> 356 F.


====
2nd up - 2 input thermometer, reads C, F - Total cost: around $26.99, w/shipping
eBay item: 260465248857
Thermocouple type: 'K'
* Temperature range: -50┬░C to 1300┬░C ( -58┬░F to 1999┬░F)
* Battery: 9V battery (installed)
* Dimensions: 149 x 71 x 41mm
* Weight: 200g ( including battery )
* Included 2 ''K''-thermocouples
* Resolution : 1┬░C or 1┬░F, 0.1┬░C or 0.1┬░F (one k-type), 1┬░C or 1┬░F (two k-type)
2 x K type temperature test probe(-50 to 250┬░C)

Downside: pretty inexpensive looking, short probes
Upside: Has degree F button. Includes 2 themocouples, better quality then the first meter, they are braided fiberglass. Can display both channels <edit:--> *one* at a time, making a low cost CHT + EGT possible.

Used the same probe as 1st test.


=== Accuracy ===
Will run some accuracy tests. Informal tests on both meters showed good accuracy at boiling water temp. Thermal compensation is present. It adjusts for errors caused by ambient temperature changes.

[elitedio]

Are these bi-metal electrodes? I have a temperature gauge on my trail tech vapor and it has two wires coming out of it.

[mousewheels]

Are these bi-metal electrodes? I have a temperature gauge on my trail tech vapor and it has two wires coming out of it.

Two conductors of differing alloys, welded at the tip. Photo shows a Fluke brand thermocouple.

P.S. I'm interested in the type of thermocouple wire the Trail Tech Vapor uses. Did not find that info in the manual on their website. Do you know what they use?

[SpyderMike]

thanks for the links bro i just put in an order for #2...how long did the slow boat from china take to get that bad boy to your door step?

[mousewheels]

thanks for the links bro i just put in an order for #2...how long did the slow boat from china take to get that bad boy to your door step?

Hey - great! Post some pics and observations when you get it going! Shipping took around 10-12 days.

[Wheelman-111]

Greetings:

Mr. Mouse, your idea and post are excellent. I think you should Sticky this somewhere. Nice job!

[elitedio]

Mouse do you mean as in measure the voltage a various known temperatures? such as 32 and 212┬░F?

Are these bi-metal electrodes? I have a temperature gauge on my trail tech vapor and it has two wires coming out of it.

Two conductors of differing alloys, welded at the tip. Photo shows a Fluke brand thermocouple.

P.S. I'm interested in the type of thermocouple wire the Trail Tech Vapor uses. Did not find that info in the manual on their website. Do you know what they use?

[mousewheels]

mousewheels wrote:... I'm interested in the type of thermocouple wire the Trail Tech Vapor uses. Did not find that info in the manual on their website. Do you know what they use?

Mouse do you mean as in measure the voltage a various known temperatures? such as 32 and 212┬░F?

I was just asking if you knew

Once the thermocouple wire is ID's we can save Vapor owners some $$ on sensors. If you want to measure it:

With the Vapor side of the wires near 70, and the probe tip in boiling water, the figures in the link below should work. Also, scroll up from the link about 2 posts and see the tables. If the ambient temperature is outside of 70 by many degrees, PM the ambient and I'll adjust the compensation factor.
http://www.hondaspree.net/phpBB3/viewto ... ple#p91377

[mousewheels]

3rd up - Multimeters
Many multimeters come equipped to measure themocouples directly. I've found some from $25 and up. Buyer can get low cost functionality with temperature, or a really nice meter. Either way, if in the market for a new DMM, think about getting one with temperature.

When shopping at the low end give a good look at the description, some may use a sensor other than a thermocouple.

Advantages: Lots of other handy functions on top of temperature
Disadvantages: Size, weight
Note: The high end of specified temperature range for the meters may require an additional accessory probe. That will be true for most all thermocouple meters. But for CHT use, the supplied probe will be ok.

Fry's has one from Extech for $29.95
http://www.frys.com/product/5160976?sit ... IN_RSLT_PG
# Thermocouple Temperature measurements to 1400┬░F (750┬░C)
# Resistance tests with Continuity and Diode functions
# Convenient mini size with protective rubber holster and tilt stand
# Data Hold locks reading in the display
# Includes protective rubber holster, battery, Test leads and Type K thermocouple probe

Harbor Freight has one for $24.95
http://www.harborfreight.com/cpi/ctaf/d ... mber=37772
Capacity: DC voltage: 2-20-200-1000V; AC voltage: 2-20-200-700V; DC current: 2mA-20mA-200mA-20A; AC current: 20-200M; Hz range: 20K; Capacitance range: 2N-20N-200N-2V-20V; Temperature probe: 20┬░ Celsius to 1000┬░ Celsius (68F to 1832F)

I bought neither of them, already have something like them. Its made by Metex, a Korean company which was an OEM supplier to a few well known US companies a couple years back. This particular model has a PC serial interface, so measurements can be captured when tethered to a computer. With a meter such as this and a laptop etc could let you capture data on the scooter for later review.

Metex Model 3860M Dual Display Multimeter with PC Interface
Thermocouple type: 'K'
-40C to 1200C (-40F to 2192F)


4th up - DMM Adapter
This is an accessory for a multimeter. It has its own battery and electronics. Basically an amplifier, temperature compensator and linearization for the thermocouple signal. The output is 1mV per degree. There is switch selection for C or F temperature units.

The example is a Fluke Model 80TK. It's pricey new, but used on eBay - about $20 to $50. Fry's sells an aftermarket model for aroun $30. Honestly, I don't have a big recommendation for this, unless you have a existing meter you'd like to keep plus have temp. For scooter monitoring, it gets a little bulky, see picture below:

Measurement Range -50┬║C to 1000┬║C (-58┬║F to 1832┬║F), depending on thermocouple probe used.
Accuracy -50┬║C to -20┬║C: 2.5% ┬▒ 2┬║C
-58┬║F to -4.0┬║F: 2.5% ┬▒ 3.6┬║F
-20┬║C to 350┬║C: 0.5% ┬▒ 2┬║C
-40┬║F to 662┬║F: 0.5% ┬▒ 3.6┬║F
350┬║C to 500┬║C: 1.75% ┬▒ 2┬║C
662┬║F to 932┬║F: 1.75% ┬▒ 3.6┬║F
500┬║C to 1000┬║C: 2% ┬▒ 2┬║C
932┬║F to 1832┬║F: 2% ┬▒ 3.6┬║F

Fluke 80TK module


--- Coming soon --->>There's 2 more meters to go - the 'good stuff'<<

[elitedio]

Mouse
I can't check this out till later. I am on vacation at the moment. No scooters no bikes with speedometers just two dirt bikes. Thanks for the direct link.

mousewheels wrote:... I'm interested in the type of thermocouple wire the Trail Tech Vapor uses. Did not find that info in the manual on their website. Do you know what they use?

Mouse do you mean as in measure the voltage a various known temperatures? such as 32 and 212┬░F?

I was just asking if you knew

Once the thermocouple wire is ID's we can save Vapor owners some $$ on sensors. If you want to measure it:

With the Vapor side of the wires near 70, and the probe tip in boiling water, the figures in the link below should work. Also, scroll up from the link about 2 posts and see the tables. If the ambient temperature is outside of 70 by many degrees, PM the ambient and I'll adjust the compensation factor.
http://www.hondaspree.net/phpBB3/viewto ... ple#p91377

[maddog]

why not just get a standard cht guage and adjust the temp with the spark plugs=5 heat ranges, lets keep it simple

[Bear45-70]

why not just get a standard cht guage and adjust the temp with the spark plugs=5 heat ranges, lets keep it simple

You real have no clue, do you?

[noiseguy]

Wow, hadn't seen an $11 thermocouple reader with probe. Nice find!

The short cable isn't that big a deal; the cheap reader's the main thing. A trip to Grainger should yield a longer, heat-shielded K-type thermocouple.

[toboggan]

hmm. i'd like to get one of these. can't wait to see the "good" stuff

[mousewheels]

why not just get a standard cht guage and adjust the temp with the spark plugs=5 heat ranges, lets keep it simple

Standard CHT gauge has advantages, tidy dash mount, quick easy read, no batteries, illumination for night monitoring.

Some reasons I'm looking at the electronic meters:

1. Some are lower cost, higher performance than an analog CHT.
   All above meters cost less just the probe for a commercial CHT.
2. Meter electronics cover extended temperature ranges. With the correct probe could monitor an EGT sensor
3. An industry standard connector is used. It's easy to set up multiple scooters with sensors, then move the meter to the bike being worked on.
4. Higher end features are available which are not present on an analog CHT meter.
5. Portability and general purpose nature can give other applications at home/work

The short cable isn't that big a deal; the cheap reader's the main thing. A trip to Grainger should yield a longer, heat-shielded K-type thermocouple.

True, there are lots of places to get K-type thermocouples. It turns out none of the meters came with probe wires long enough to route to the handlebars of the Elite. The 3ft or so length that all meters came with worked fine with the Yamaha QT50 used for the first on bike tests.

Low cost Type K thermocouples $6.50 for 2 probes, two meters long
For CHT measurement, we don't need a high accuracy grade of thermocouple. Just received were a set of these low cost probes.

TP-01 Type K Thermocouple Probe/ -50 to 250┬░C (~480F) ( 2 x 2M)
Accuracy : < 250┬░C ┬▒ 1.5┬░C
Sample eBay Item number: 250492500877
$6.48 with shipping