How Much Longer Will Cars Have Cigarette Lighter Ports?

Depending on the age of your car, it might contain a round 12 V power outlet in the dash, or possibly in the elbow compartment. And depending on your own age, you might know that as the cigarette lighter port. Whereas this thing used to have a single purpose — lighting cigars and cigarettes via hot coil — there are myriad uses today, from charging a phone to powering a dash camera to running one of those tire-inflating machines in a roadside emergency.

But how did it come to be a power source inside the vehicle? And how long will it stick around? With smoking on the decline for several decades, fewer and fewer people have the need for a cigarette lighter than do, say, a way to charge their phone. How long will the power source survive in this configuration?

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First Stab At Motion Sensor To Disconnect A Car Charger

motion-sensing-car-charger

 

[Pixel] just sent in this automotive hack which disconnects his car charger when the vehicle stops moving for at least 10 minutes. Why would you need such a thing? The 12V outlet in his vehicle isn’t disconnected when the ignition is turned off. If he leaves a charger plugged in when parking the car, he often returns to a drained battery.

The fritzing diagram tells the story of this hack. He’s using a 7805 to power the Arduino mini. This monitors an ADXL362 accelerometer, starting the countdown when motion is no longer sensed by that chip. At the 10-minute mark the N-channel MOSFET kills the ground side of the outlet. Good for [Pixel] for including a resetable fuse on the hot side. But it was the diode all the way to the left that caught our eye. Turns out this is part of a filtering circuit recommended in a forum post. It’s a Zener that serves as a Transient-Voltage-Suppression diode.

Another comment on that thread brings up the issue we also noticed. The 7805 linear regulator is constantly powered. Do you think putting the uC into sleep and leaving the linear regulator connected is an adequate solution? If not, what would you do differently?

Battery Desulfator

mini-d

Hack a Day favorite [Mikey Sklar] is back with a new project. Mini-D is a battery desulfator. If a 12V lead-acid battery sits with a voltage below 12.3V, sulfur crystals will begin to form on the lead plates. This crystal growth increases the internal resistance and eventually makes the battery unusable. A battery desulfator sends high frequency pulses through the battery to create a resonance that will break up the crystals. On a 60lb automotive battery, it will take approximately three weeks to completely desulfate. You can find schematics plus a dozen lines of code for the ATmega169 on his site. Embedded below is a video where he explains the device and other techniques like load testing.

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