How to power a Raspberry Pi from your car battery


The Raspberry Pi mini PC requires 5VDC power at around 500-700mA, so you can’t just plug it into your car’s 13.8V power system and expect it to survive. But there are a couple of simple options to getting a Pi powered up and running from your car’s electrical system.

The first is a USB car power adapter that plugs straight into your car’s cigarette lighter. If you go for a two-port model, you can plug the Raspberry Pi into the 1A port and the USB peripherals into the higher-powered 2A port (this is normally reserved for iPads but can be used to power USB hubs). You can find these on eBay for under $5 including shipping.

The second option is a little more complex but can produce more power – a DC-DC step-down converter like this one can produce 5VDC output at up to 3A, which is enough to power a Raspberry Pi and a number of peripherals, even USB hard drives. Again, these are available on eBay for under $5 including shipping.

But this step-down converter has one other trick – it’s able to also take the 24VDC output from a truck’s electrical system and churn out the required 5VDC for your Raspberry Pi. Unless the truck cigarette lighter is designed to output 12VDC, the plug-in socket USB adapters won’t work, which is why the DC-DC step-down module is a good universal option that works regardless.

Another option that requires a bit more electronics is to use a linear voltage regulator like the LM7805 series – these are three-terminal regulators that output 5VDC regulated at up to one-amp – more than enough for the Raspberry Pi itself. The problem with the 7805 is that while it works exceptionally well at what it does, it’s a ‘linear’ regulator, which means it’s not particularly efficient. When connected to your car, an LM7805 will dissipate most of the power it uses as heat – in other words, it’s only about 40% efficient.

DC-DC step-down converters are more efficient because they use switching circuitry to step down the voltage in such a way that the process is around 90% efficient. They waste less energy and produce less heat, which means they run cooler and are better for confined spaces.

Whatever option you use, you should be able to find a suitable method to running your Raspberry Pi from either a car or truck.

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