successful carputer in winter environments
I go to school at Michigan Tech, for those of you that don't know its about as north as you can go in Michigan before being in Lake Superior - we get over 250 inches of snow a year and can have temps as low as -10F to -15F. I built a carputer last spring but had been worried about how well it would perform in the winter. Surprisingly I had very few problems throughout this winter.
I have a miniATX system in my trunk. In a snowy envirnoment you will invariably get snow in your trunk when you are parking it outside all winter. I have heard people on other threads worry about this causing humidification and other problems. I had no problems whatsoever. What happens is once you turn ur comp on it becomes the warmest item in the trunk. If you leave it on for long enough it can cause snow in your trunk to melt and evaporate. However the body panels around your trunk are the coldest surfaces. This causes water to condense on them first keeping your pc naturally dry. then once you turn your computer off it will take the longest to cool down therefore all the humidity in the air is already condensed and frozen to other surfaces by the time the computer gets cold. I had so much humidifaction that a couple times I opened my trunk after running the carputer and water was dripping off the underside of my trunk. Another time i came out to my car after it had been sitting for a day and there was afilm of ice across the entire underside of the top of my trunk. But yet I never had a single problem with the computer.
Many people have also had worries about it being to cold for the hardware to function properly. I have only noticed this to be true for one piece of hardware: the DC to AC power converter. Originally I had a 1000watt RMS DC to AC Vector brand power converter. Using this I started the computer up from -10F multiple times without any hicups at all (the refresh rate on my lcd was pretty bad until it warmed up but the touch sensitivity worked fine). I had other uses for the large DC to AC so I bought a substitute Black and Decker 400 watt dc to ac converter. This converter struggles with temperatures below 5F. flipping the switch on it results in it outputting far to low of an AC voltage I have to let it run for some time (up to several minutes depending on initial temp) in order to let it warm itself up. once warmed up the computer boots up just fine off of it. I don't know if the reason was a difference in brands or a difference in wattage output (my comp PSU is only 300 watt however) that caused the instability in cold. all the other components functioned excelently in the cold. one one extremely cold day (-15F) I came out to my car to find that the lcd housing had contracted at different rates than the screen so the film screen actually was bubling out at me, and there was ice/frost frozen to the front of the screen. I booted the computer up like normal and after running for 5 minutes the screen was completely fine and I had absolutley no problems from it whatsoever.
I guess I just wanted to give some confidence to other northerners who are investigating building a carputer but hesitant about its reliability in the cold.
One other note I had dual batteries separated with a battery isolator, but the isolator stopped functioning. I don't know if they aren't built for those types of temps or if mine just broke. either way it broke over one of the coldest weekends of the year.