OptimusPrime

I have been thinking of ways to automate the startup and shutdown on my Carputer and came up with this...

I am not an expert on wiring and electronics, so please bear with me.

If i turn on the ignition, the relay will turn on the inverter which then boots my Carputer (its set on resume following power loss).

Now when i turn off my ignition, the PC detects the loss of the 5v on the serial port and shuts down (generic UPS installed?). The inverter should stay on at this point as it still has 12v being supplied to the relay to keep it on.

Once the PC has shut down, the relay loses the 12v from the PC and turns off the inverter?

Can someone cast an eye over this and let me know if it will work...



Cheers

OP

Bazza_84

cant see how u r going to get 5v from a 12v ignition system?

OptimusPrime

I have found a 5v source (5.35v to be exact), although i am not sure what its for.

It comes on and goes off with the key (ACC position) and does not alter when i turn on anything in the car, lights, wipers etc..
(It drops to 5.15v when the car is running)

So hopefully that will be ok to use. If not could i simply use a 1A 5v voltage regulator to drop it to 5v?

OP

DarquePervert

Why would you need to feed 5v to the computer?

If anything, you could get the 5v from the computer, since the PSU of the PC is getting it's power from the inverter, and the PC's PSU created 12vDC, 5vDC and 3.3vDC.

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lbridges

Although I admit I've never tried something like that you suggest, it seems likely to me that the system would get confused when starting the car. By that I mean it will see 12V at the relay when the key passes the ACC setting, then either go off, or drop low when cranking.

I would suggest the use of a voltmeter to watch signal strength as the key moves from one position to another just to make sure the system will behave as you hope.

One other thing to think about. Relays can produce voltage spikes when cycled. I'm not sure what you're using as the 12V source off the ignition or off the compuer, but you might also consider type of protection (diode?).

OptimusPrime

I may have confused myself...lol (i will have to check back through the old posts again later) I thought you could install a generic (fake) UPS on XP and as long as you keep >5v to a pin on the serial port the PC will stay on, the moment the 5v drops the PC does a controlled shut down?

The PC would then shut down, which would remove the 12v signal from the relay, which then turns off the inverter...


The 12v from the ACC stays on while the car is running and only drops to 11.5v under normal cranking, then upto nearly 15v while the engine is running. (I do have a much larger Battery and uprated Alternator to cope with my 2 x 1000wrms amps, so this may help).

For some reason, my PC has never booted from my inverter while my engine is running (i just flicks back and forth between the red and green lights on the inverter). I always have had to turn on my PC, then crank the car. The PC doesnt seem to mind the cranking, it continues to boot normally.

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I installed the relay on its own today, just using it as you normally would. From my ACC to the relay, then to the inverter.

When i get in the car i now have to do the following. Turn the key to ACC, wait for the PC to turn on (i can see its on by the LED i installed in the center console), which is only about 1 second, then start the car.

I am quite happy doing this to start it up, its just the shut down to test now...

At the moment i have to press my power button (also in the center console), wait about 5 seconds for the PC to shut down, then turn off the key.

I suppose i could just turn off the key, but i don't think my PC would like that too much...lol

As long as i didnt dream up the >5v to the serial port idea, i think this may work. I'm sure i also read somewhere the serial port can take up to 25v DC (regulated), if this is the case, i may just be able to apply the 12v from the cars ignition.

I do think i will have to use some sort of Diodes to stop the 12v from the ignition going into my PC and vise versa.

Regards

OP