Do you sometimes enter your car on a sunny day, and the thermometer is really high? Your car doesn’t have an inbuilt thermometer but a thermistor. Perhaps you’re now asking yourself where it’s located in your car. You may also be wondering why heat or wind doesn’t affect it.
Cars don’t come with inbuilt thermometers but thermistors. A thermistor determines a change in electric current from adding or removing heat. The device is usually placed on the grille where heat or wind is less likely to affect its performance.
What Is A Thermistor?
A thermistor is a solid-state component in a car built from semiconductor materials. The thermistor is highly sensitive to temperature, and its resistance value changes when the temperature changes too. A rise or fall in the temperature affects the thermistor’s resistance.
Thermistor options include Positive Temperature Coefficient (PTC) and Negative Temperature Coefficient (NTC) thermistors. An increase in temperature causes an increase in the resistance value of the positive temperature coefficient thermistor.
How Does A Thermistor Work?
Temperature Coefficient Resistance (TCR) measures the temperature change in resistors while they are in use. TCR is a change in resistance resulting from a change in temperature expressed as a percentage. A large TCR in thermistors is necessary to measure temperature.
The thermistor is placed on the body whose temperature needs measuring with a connection to an electrical circuit to work as a temperature sensor. A change in the device’s temperature changes the resistance of the thermistor.
A circuit with a direct connection records the change for calibration against the set temperature. Thermistors have two wires, with one connecting to the excitation source to determine the thermistor voltage.
For an accurate reading, the thermistor reads any adjustment in resistance during temperature change.
Why Are Thermistors Used In Cars?
Thermistors are used in vehicles than thermometers because of various special features, including:
Affordable
One of the most outstanding reasons for using thermistors over thermometers in cars is the cost-benefit. A thermistor provides accurate and precise data regarding the temperature in your car at a considerably low cost.
Small Size
Another reason for using thermistors in cars is their compact design. Thermistors are designed in different forms, including rods, discs, and beads. Choosing a form that will fit in any car is so easy. And these devices are extremely durable regardless of form or size.
No Overheating
The flow of current in an electrical circuit generates heat which dissipates. The heat generated increases the temperature of the resistor. However, the thermistor reduces heat on reaching its definite amount of resistance.
Exceptional Accuracy
Installation of a thermistor is at a given distance from the circuit. Doing this ensures that there are no errors in reading resulting from resistance in the lead.
Thermistors operate in a small temperature range making their readings more precise. This is because of their rapid response to the slightest change in temperature.
High response time
Thermistors respond to the slightest changes in temperature. This allows them to provide instant data with a minimal delay because the thermistor monitors a small temperature range.
Inrush Advantage
Charging a device when turned on exposes it to extremely high currents, known as inrush. Protection is necessary to keep the device safe from damage or other detrimental effects.
Fortunately, NTC thermistors perform extremely well as inrush current limiters to protect sensitive circuits. This saves them from problems that may result from inrush currents, including:
- Damaging capacitors
- Destruction of rectifier diodes
- Harming power switch contacts
Thermometer Vs. Thermistor
A regular thermometer uses a liquid to determine the temperature. This liquid expands and rises in heat and contracts to reveal the current temperature. Removing heat makes the liquid contract and fall to reflect the temperature fall.
A thermistor measures the temperature change in electrical current after adding or removing heat. This device works just like thermometers but without the use of a liquid. Thermistors are convenient since they are tiny, accurate, and cheaper to make.
Where Is The Thermometer Located In A Car?
For this article, let’s keep using the thermometer and thermistor interchangeably. Vehicles have the thermistor in front behind the grille because this place has more open space and airflow. However, you can’t say the same for an aftermarket grille.
Why Isn’t the Thermistor Affected By Heat Or Wind?
There’s a lot of concern regarding whether the car thermometer reading isn’t affected by heat or wind. The thermistor in your car is strategically placed, so the temperature from the engine doesn’t influence its reading.
Thermistors are located behind the grille but in fenders, behind the mirror housings, or in front of the radiator. Wind chill only affects living creatures. Therefore, there’s no need to worry about the wind affecting the thermistor reading.
Overall, heat and wind don’t affect the thermistor’s accuracy. However, the road may give off re-radiated heat, affecting the temperature reading. This may lead to reading a high temperature if you park on hot pavement.
There’s no solution to avoid re-radiated heat’s effect on your thermometer’s accuracy. Fortunately, it only inflates by a few degrees unless the weather is extremely sunny.
A thermistor is a device for reading temperature in cars but not a thermometer. Thermistors are cheap, small, and give more accurate temperature readings. The device is installed on the grille where heat or wind has no impact on its performance.
