With all due respect to @thagrol and @MikeDB, both of whom have contributed a lot of useful advice on this forum over the years (edit: far more than I have!), your answers here were not the best.
@thagrol: A buck converter is regulated on its output voltage, so the stability of the input is rather irrelevant as long as it is well designed. This is why a cheap inverter is acceptable to power the Pi power supply.
Sure they're regulated on their output. But that isn't my point.
Not all buck converters are created equal. Some have narrower input voltage tolerances than others. My point is to get one that covers the full range of potential voltages. And that despite what is advertised, the 12V supply in a car is not guaranteed to be 12V nor guaranteed to be stable. Or noise free for that matter.
As for those in car phone charger adapters, I ran an A+ in my car for several years on one of those. Had to add an I2S DAC to it as the onboard audio picked up interference from the alternator
. Didn't worry about stop/start and OS corruption as I used the read only root overlay.Of course, an A+ needs a lot less current than a Pi5 with
I maintain that the best solution is to pair a 12V inverter with the official Pi power supply he already has.
I'm going to disagree with you there. Firstly because a damp/humid environment* like a car is not a good place to be using indoor use only rated mains voltage equipment and secondly because it'll be horribly inefficient (12V DC to 110V/240V AC to 5V DC). Don't forget that, unlike your home's mains supply there is an upper limit to what you can draw in a vehicle without fully discharging its battery. Drawing more than the alternator can produce is OK for a short while, doing so long term will lead to a flat battery.
It's you risk but using an inverter is not something I'd want to do - the only time I've used main voltages in a vehicle were in a stationary camper van with a certified mains hookup and RCDs in circuit.
And while you're at it, don't forget that you'll need some way to prevent OS and data corruption on an unsafe shutdown and a way to prevent the Pi fully discharging the vehicle battery if opt for a permanently on connection.
*: though that depends on the environment where you live and where you will be using the vehicle.
Statistics: Posted by thagrol — Tue Nov 12, 2024 1:25 am