CarPC Shutdown Controller

inverter

I’m sure most people that have built a CarPC are already familiar with shutdown controllers, but I think this hack is pretty clever. Computers don’t like being turned off suddenly so you need to figure out how to power down the PC safely. This circuit has a serial connector and appears to XP as a generic UPS. When the ignition is turned off it breaks the 5V line to COM pin 8. XP responds by hibernating. Once the computer shuts down the relay for the power inverter opens. When the ignition is switched on the inverter powers up and the computer turns on.

[thanks SilverPill]

25 thoughts on “CarPC Shutdown Controller

  1. wow dave, you really impress me with your lameness.

    This is a really cool system. I just hope that you can set windows to go into hibernation mode. The bootup is much faster. I have all my media centers setup that way.

  2. Instead of the second diagram you could put a cap from the coil of the upper relay to ground and size it so that you have enough time to start your car without having the computer go into sleep mode (if your car doesn’t have the key switch). You can size the cap to give you 5, 10 or whatever seconds you need. The only issue I can see with doing that would be that the power down of the system would also be effected by this delay (unless you also add one more diode).

  3. What is the facination with contorting a home PC to run in a car?? Why not just use a laptop and be done with it?? Already designed to run on DC power, comes with a builtin battery backup, builtin display in the event the in-car display fails, low profile form factor, somewhat ruggedized, etc etc…

    Ahwell.

  4. Because you can, you do it because you can.

    However, i run a computer in my car because i allready had the components sitting about (free!) but it only plays music and runs headless so its a bit diffrent from a full carputer setup.

  5. @6…. check out that website – look at some of the setups and you’ll see why a laptop is not just used (most of the guys on there are never just done with it) :P A lot of setups aren’t even home PCs – they are specifically designed as a carpc o.0 And AFAIK, my PC is running on DC power :P
    ——
    A whole lot cheaper than going DC-DC. I am using something similar with an over ride button to keep the PC on should I want it to (for say uploading music from my PC). I also have a timer built in for those times when you shut your car off for a minute or so while waiting in line for something :D

  6. This is really off topic
    but i bought a wrt56gl a while ago and it will not hand out ip adresses
    ive tried everything i can think of but i just cant get it to work.
    could someone please help me
    danno

  7. You’re right, danno, that’s really off topic. Maybe you should take your tech support question someplace that it is welcome. Try google; there are tons of tech help forums.

  8. As a mp3car user myself (known as kirbycope) this hack is unappealing to most of our users. Most prefer a dc-dc psu with startup/shutdown incorperated such as OPUS and M2-ATX. Cost really isn’t something you want to spare on these.
    Laptops are for cheaters. Actually they generally take up more space with the docks and are a little more expensive unless you have a spare.

  9. #14
    DC-DC PSU and a mains power PSU are two ways you can power a carpc. DC-DC is more expensive, you need the DC-DC converter itself, and you must build a computer with a relatively low power consumption. But, you’ll end up with a cleaner power supply (not that it matters to the carpc itself IMO as long as you are within tolerances). You also have more options as far as startup and shutdown controllers go.

    If you use a power inverter, you can use a standard PSU. This method does not cost as much, but it has a few drawbacks. It will most likely put feedback into the power system which you will hear in your audio. It is also not very efficient – you are going from AC-DC (car alternator to rectifier) back to AC (inverter) and then the PSU goes to DC. But, if you have an older computer that is power hungry – it can be a good compromise. — Why use an older computer? You really don’t need much computer power to run most functions.

    If I had the money to do it – I would be using the opus DC-DC PSU as mentioned in #13

  10. Recommendation:

    Add a switch between the diode from the ACC line and the relay. This switch will tell the car not to turn on the computer if you are not going to use it. Flipping the switch on while driving will provide power to the relay and boot the computer. For shutdown while driving, just have something in whatever interface you use to issue a hibernate command, which I dont’ know how to do, or you can issue “shutdown -s” to actually log off and power down, of course the next time you turn it on it will go through a full startup.

  11. Recommendation:Add a switch between the diode from the ACC line and the relay. This switch will tell the car not to turn on the computer if you are not going to use it. Flipping the switch on while driving will provide power to the relay and boot the computer. For shutdown while driving, just have something in whatever interface you use to issue a hibernate command, which I dont’ know how to do, or you can issue “shutdown -s” to actually log off and power down, of course the next time you turn it on it will go through a full startup.

  12. THIS IS A VERY VERY BAD WAY OF DOING IT. If you run the wiring like this to keep 12v so it can hibernate then your putting very unclean power to the 12v rail. Most components don’t like 11-16vdc that you’ll be opening them up to if you connect it this way. I think you only need like 1amp or so for hibernation/suspend on the 12vdc rail so at least use a good filtered 12vdc power supply.

  13. As a side note to the many excellent comments, there is a different solution for Mac users…

    MP3Car.com has tons of info about dc-dc regulators for CarPCs (opus etc)… I personally used the Carnetix P1900 in my Grand Cherokee to power a Mac Mini. I get a good “sleep” and “wake” signal from it, and efficient use of power. http://www.carnetix.com has info for the Mac Car Computer enthusiast.

    1. I visited carnetix and the cnx-p1290 was looking good until I saw the part regarding standby mode. If the carputer doesn’t properly go into standby, the ps will catch fire! duh… uh.. I don’t think so! The ps needs to sense current draw, and also needs to shutdown if the battery is getting drained too far. Oh well.

  14. to (21: alpha) I think you will find that the diode stops 12v from running from the ignition into the supply for the motherboard. In fact you should be thinking of the 12v from the PSU is actually keeping the main power relay closed after the ignition is turned off. When the PC has hibernated/turned off, it then releases the main relay and removes power from the inverter.

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