Ebay CHT Gauge Options

[913B]

https://www.ebay.com/itm/117440308539

What's your opinion on this item, junk? Try it and let us know (IMG:style_emoticons/default/biggrin.gif)

[FlacaProductions]

first thing i see is that it's not temperature compensated - meaning, it's going to be affected by the ambient temperature and won't give consistent readings.

It only measures the difference between the hot end (your cylinder head) and the cold end (up at the gauge). So on a plain gauge, the reading drifts with ambient temperature — same engine, colder day, lower reading.

A temperature-compensated gauge corrects for that. It measures the ambient temperature at the gauge end and adds it back in, so the needle shows the true head temperature no matter the weather. Worth having on an air-cooled engine, since CHT is the number you're actually managing.

[Superhawk996]

first thing i see is that it's not temperature compensated - meaning, it's going to be affected by the ambient temperature and won't give consistent readings.

It only measures the difference between the hot end (your cylinder head) and the cold end (up at the gauge). So on a plain gauge, the reading drifts with ambient temperature — same engine, colder day, lower reading.

A temperature-compensated gauge corrects for that. It measures the ambient temperature at the gauge end and adds it back in, so the needle shows the true head temperature no matter the weather. Worth having on an air-cooled engine, since CHT is the number you're actually managing.

The unit in question is not a thermocouple based gauge. Therefore, cold junction compensation wouldn’t apply with this gauge.

Technical Specifications:

Power consumption: < 3W
Power supply: 12V DC
Output: 2 outputs with 10 Amp load
Temperature range: -30 to 300 °C (-22 to 572°F)
Sensors: Two, each with a 3m (10 ft) wire length
Sensing Tip Material: washer-type copper sensor
Inner Washer Diameter: 14mm
Sensor Type: Negative Temperature Coefficient NTC Sensor. <—— not a thermocouple

A Negative Temperature Coefficient (NTC) sensor is very different vs. a thermocouple. A NTC sensor decreases in resistance as temperature increases.

A thermocouple actually generates a micro-volt output between two dissimilar metals that increases its output voltage as temperature increases.

Two totally different temperature measurement technologies.

The ring end of the sensor doesn’t have typical thermocouple wires like a VDO or Dakota Digital gage has. There appears to be a silicon based NTC sensor crimped into the spark plug ring. Down the road - could be a problem finding replacement sensors if one of these were to fail. Would need more details on what the actual sensor element resistance curve is to have any hope of finding a future replacement.



The idea that it can control up to a 10A output load based on temperature could be useful in some case?

I’m always leary of EBay stuff but who knows - might be useful to someone to control something. (IMG:style_emoticons/default/idea.gif) The ability to monitor both cylinder banks could be entertaining.