FACTS, FICTION…MY OPINION (Did you know)How do you read a gas gauge on a car?
FACTS, FICTION…MY OPINION (Did you know) How do you read a gas gauge on a car?
FACTS, FICTION…MY OPINION (Did you know) How do you read a gas gauge on a car?
Bruce Bisbey
Executive Producer / Partner Dumb Dog Productions — Media Arts International Film Corporation
How do you read a gas gauge on a car?
What does the fuel gauge tell you?
In automotive and aerospace engineering, a fuel gauge is an instrument used to indicate the amount of fuel in a fuel tank. In electrical engineering, the term is used for ICs determining the current State of Charge of accumulators.
The lines on the gas gauge are increments of 1/4 representing your gas tanks fuel level. Anything between 2 lines would be an eight. If the needle were between 1/2 and 3/4, this would mean you have 5/8 of gasoline in your tank.
The line lowest to the bottom would mean you have 1/4 of a tank of gas and you should probably fill up soon, below 1/4 would be close to 1/8 of a tank which means get gas now. Newer vehicles have a low fuel light that illuminates and often come equipped with technology that informs you on how many miles you can proceed before running out of gas.
As used in vehicles, the gauge consists of two parts:
The sending unit — in the tank
The indicator — on the dashboard
The sending unit usually uses a float connected to a potentiometer, typically printed ink design in a modern automobile. As the tank empties, the float drops and slides a moving contact along the resistor, increasing its resistance. In addition, when the resistance is at a certain point, it will also turn on a “low fuel” light on some vehicles.
Meanwhile, the indicator unit (usually mounted on the dashboard) is measuring and displaying the amount of electric current flowing through the sending unit. When the tank level is high and maximum current is flowing, the needle points to “F” indicating a full tank. When the tank is empty and the least current is flowing, the needle points to “E” indicating an empty tank; some vehicles use the indicators “1” (for full) and “0” or “R” (for empty) instead.
The digital fuel gauge in a 2018 Mazda 3 showing a nearly-empty tank along with a distance to empty display.
Typical old-style fuel gauge on a 50 ccm Chinese-made scooter from 2008, with the internationally used pictogram of a gas pump. The system can be fail-safe. If an electrical fault opens, the electrical circuit causes the indicator to show the tank as being empty (theoretically provoking the driver to refill the tank) rather than full (which would allow the driver to run out of fuel with no prior notification). Corrosion or wear of the potentiometer will provide erroneous readings of fuel level. However, this system has a potential risk associated with it. An electric current is sent through the variable resistor to which a float is connected, so that the value of resistance depends on the fuel level. In most automotive fuel gauges such resistors are on the inward side of the gauge, i.e., inside the fuel tank. Sending current through such a resistor has a fire hazard and an explosion risk associated with it. These resistance sensors are also showing an increased failure rate with the incremental additions of alcohol in automotive gasoline fuel. Alcohol increases the corrosion rate at the potentiometer, as it is capable of carrying current like water. Potentiometer applications for alcohol fuel use a pulse-and-hold methodology, with a periodic signal being sent to determine fuel level decreasing the corrosion potential. Therefore, demand for another safer, non-contact method for fuel level is desired.
Further explanation:
If the gas tank on a car holds 20 gallons of gas, and the gauge read “1/2”, you have 10 gallons of gas. If your car gets 30 miles to the gallon, this means you can drive about 300 miles on a half tank of gas. Warning: Driving your vehicle on low fuel or an empty tank can damage your ride or even lead to a crash.
Now the fuel gauge in your car or truck is actually lying to you. Automobile manufacturers build in about a gallon (3.8 liters) of reserve fuel beyond the “empty” line. They also warn about low fuel long before a vehicle runs out, since they know that people procrastinate.
But those manufacturers are looking out for drivers: Running out of fuel can leave you stranded or cause a crash on the road, and can also damage expensive auto parts.
Sources / Credit: AAA, Pinterest, Wikipedia, The Food Network, Amy Reiter, Erin Blakemore, Smithsonian Magazine, Lyn Kelly, Trendy Matter, Nevada Drive Academy of Las Vegas — Henderson Driving School
THIS ARTICLE IS FOR INFORMATIONAL PURPOSES ONLY. THE INFORMATION IS PROVIDED “AS IS” AND BRUCE BISBEY MAKES NO EXPRESS OR IMPLIED REPRESENTATIONS OR WARRANTIES, INCLUDING WARRANTIES OF PERFORMANCE, MERCHANTABILITY, AND FITNESS FOR A PARTICULAR PURPOSE, REGARDING THIS INFORMATION. BRUCE BISBEY DOES NOT GUARANTEE THE COMPLETENESS, ACCURACY OR TIMELINESS OF THIS INFORMATION. YOUR USE OF THIS INFORMATION IS AT YOUR OWN RISK. YOU ASSUME FULL RESPONSIBILITY AND RISK OF LOSS RESULTING FROM THE USE OF THIS INFORMATION. BRUCE BISBEY WILL NOT BE LIABLE FOR ANY DIRECT, SPECIAL, INDIRECT, INCIDENTAL, CONSEQUENTIAL OR PUNITIVE DAMAGES OR ANY OTHER DAMAGES WHATSOEVER, WHETHER IN AN ACTION BASED UPON A STATUTE, CONTRACT, TORT (INCLUDING, WITHOUT LIMITATION NEGLIGENCE) OR OTHERWISE, RELATING TO THE USE OF THIS INFORMATION.
Gas Gauge / Photo Credit: Pinterest
