This is actually something I've been working on myself. I've always wanted to have a car like KITT from Knight Rider since I was about 12 years old and that's one of the reasons I got Ultrahal. I don't have the computer in the car yet, and my training of Ultrahal is in the very early stages, but I have put much thought into putting a computer into the car, how to power it, how to keep it cool, and how to prevent a hard drive crash. I too would like the computer hardwired into the car and would like to be able to have it going even when the car itself is off.
One of the easiest solutions would be to get something I've seen called a "carputer." Basically it's a heavy duty computer that's designed for the abuses of being housed in a car. I've not looked much into these yet, so I don't know how much more they cost than a standard desktop computer. That's probably the easiest and best solution, but maybe not the cheapest or the best if you're looking to use what you already have.
Going the route of installing a desktop in the car, here's what I'm thinking.
Power
I'd power this off of a separate battery from the car. I really wouldn't want to find myself stuck with a dead battery at some point while trying to start the car. I'd use a dry cell marine battery as these are designed for continous drain whereas a typical car battery is designed for cranking the car during starting. I would get a battery isolator (isolator and wiring can be had for $50-60 from Pep Boys, JC Whitney,and other car parts suppliers) so that I could charge the dry cell battery from the car's alternator. You need to have the isolator to keep the charging of the two batteries separate. Alternatively, you could just charge the battery with a battery charger every night. I'd also get a power inverter to convert the 12 volt DC from the battery to AC. Prices for power invertors vary by wattage and brand -- really anywhere from about $30 upwards. I would probably go with at least a 400 watt invertor myself, but the best thing to do is to calculate the wattage of the items you want to power and go just a tad bit more.
Theoretically, you could instead power a desktop computer directly from the battery without the invertor. It would probably be more energy and space efficient. The power coming out of the power supply transformer in a typical desktop has both 12 volt and 6 volt lines. If you went this way you'd need a voltage divider to get the 6 volt power. Personally, I'm a little leary of connecting the motherboard and other devices within a laptop directly to a 12 volt battery without some kind of additional electronics to prevent surges or spikes in the system, but I could be overly worried for nothing. Has anyone here ever powered a desktop directly from a 12 volt car or marine battery?
Cooling
In my mind, cooling is a very high concern. The temperature in a parked car can get very hot, especially in a black Trans Am. I have two ideas, neither of which I've had the opportunity to test. Both involve using a part out of a 12 volt car cooler. Most 12 volt coolers these days that plug into a cigarette lighter have a device with a little plate on it that can be used either to cool or to warm food. The actual part that does this is not very large and can easily be removed from the cooler itself. It's got a metal plate that gets cool or warm depending on the voltage polarity applied to it.
Whichever option I choose, I'd also want to make sure the computer case is well insulated to keep the cool in and the heat out. One concern I have about either method is condensation. If it gets too cold in the computer case on a warm humid day, I'd be concerned about condensation forming in the case. Possibly this wouldn't be a problem if the cooling unit was external to the computer case and the temperature was kept cool, but not too cold. Theoretically, you could set the cooling unit to warm if you wanted to keep the computer warm in sub-freezing temperatures in the winter.
Option 1: Air cooling. More or less I'd just hook up the cooling unit in a way that the cool air gets pulled into the computer case through the cooling fan or adding a separate fan and some kind of air duct to pull the cool air into the computer case.
Option 2: Water cooling. I've seen water cooling systems designed for computers that run water or some kind of coolant through tubing that circulates inside the computer case to cool the cpu and other parts. I could be wrong, but I don't think these things actually chill the water going in, but with the cooling unit from a car cooler you could probably chill the water outside the case and pump it in.
Hard drive protection
I'm not entirely sure the answer to this one. I'm thinking just make sure the computer case is on something like a gel pad or something else that provides some shock absorbtion. Or maybe a laptop hard drive if these are designed to take shocks and drops better. Another option would be to have a small inexpensive boot drive for booting the computer, and having a flash drive or external hard drive to house any important data. If the boot drive crashes, you don't loose too much of importance or have to spend to much on a replacement.
Some other things I'd want on my car computer
I'd probably run a wireless keyboard and run either a trackball or a trackpad. I don't see a mouse as being too practical in a car.
I'd have a video card with audio / video outputs that I could run directly to a car video monitor or stereo system with video display.
I would have an extended range wireless network card. At minimum, I'd be able to connect to the internet for updates and internet from the driveway without having to run a network cable to the car every time I wanted to update anything. Theoretically, I'd also be able to pick up an internet signal from the parking lot anywhere there was a wifi hotspot.
As far as Ultrahal is concerned
I'd love to be able to have some sensors and controllers wired to the computer and interfacing with Hal to give him some basic self awareness and the ability to activate things on the car.
Sensors -- maybe to know the speed the car is going, whether forward or reverse, whether the lights are on or the windshield wipers so the AI would know it's raining and be able to say something appropriate. It would also be cool to have Ultrahal hooked to a car alarm and programmed to speak or react in certain ways if the alarm sensors get tripped.
Controllers -- things like the trunk, power locks and power windows, headlights and some other things that would be fun to have voice controlled
Anyway, those are my thoughts. I haven't gotten to the point of building or testing any of these, but if anyone does try them I'd love to hear about it.
Mel
