In-Car UPS-style power

[ledow]

Just had an email from LinITX.com because, months ago, I was looking at building a Mini-ITX computer to work inside the car (and monitor it when the main ignition was off).

They sell this:

http://linitx.com/product/12770 

A 12v dual-power-source "UPS" for a car.  Stick your ignition's 12V on one set of inputs, and a lead-acid battery on the other set and when your car is running it will use the car battery and charge the backup battery, and when it's not running, it will use the "backup" battery to ensure consistent, uninterrupted 12v power to your project.

Thought it was useful enough back then to mark when they got more stock and that's what they were emailing me about - they have them again. Obviously, you'll need to do some voltage-conversion but dual-input, self-charging, regulated power in a car seems a good match for a lot of the projects that people have planned for the Pi.

[SN]

Looks good but also looks a little 'fragile' if the second 'lead acid battery' is a full sized affair - I have a Land Rover with a second battery holder and I'd be wanting to drop a full size gazillion amp 15V battery in there - this device only handles a 10A/12A draw, perhaps I need something a bit bigger (so I could also hang things like in-car beer chillers etc of it )

[DarrenThomas]

If you are just going to run your Pi, you may as well just run it via a relay and switch, rather than from your ignition. The Pi only needs 700mah. Even you had the smallest car battery, it would be around 30,000mah, which would power the Pi for 42hrs at full drain.

I will be wiring mine so that it powers off with the ignition, unless the switch is on, in which case it will stay on. I am also going to look at a timer, so if the ignition is turned off and the Pi is on, it will turn off after XX mins, just in case it is left on by accident.

Daz

[error404]

Unless you run the system read only, you really should give it a chance to shut down properly or eventually you'll probably screw it up enough that it won't boot when turned back on. There's a long thread on some ideas on how to do this gracefully somewhere.

I'd use a transistor to safely monitor the ignition switch state with a GPIO and trigger a shutdown when the ignition is turned off (or some time thereafter). Having the Pi actually power itself off is a bit tricky, however, and that's where that UPS gizmo might be useful (you could also use a solar charge controller; probably cheaper), to protect from draining the car battery.

[fhlipZero]

i used to have a mini dell tower along with full display and everything wired into a Chevy Blazer and powered by an inverter and ran into the same problem. Shutting the car off instantly kills the computer so i just made use of the "Hibernate" option on windows. Shut down fast, and started right back up fast, i am still awaiting delivery of my pi so i don't know if this works on any of the linux distros but might help

[AndrewS]

i just made use of the "Hibernate" option on windows. Shut down fast, and started right back up fast

Discussed in this thread http://www.raspberrypi.org/phpBB3/viewt ... =31&t=6410

[Lob0426]

That board probably came from here.
http://www.mini-box.com/micro-UPS-load-sharing
For those of us in the U.S. this will be a better link. There other options there also. I run one of their pico PSU's in my Windows Home Server.