Thread: COOL carputer with AC?

Here are some pics of my install in the glovebox . As stated in the post, the highest temps I've experienced with A/C cooling was 56 degrees C (at idle with A/C cooling the temps are low 30's). It's gotten up to about 70-75 degrees C when I had the carputer running in my garage without any cooling. However, if I open the glovebox then the temps dip to about 60 degrees C.

thats alittle different then blowing the ac directly onto the board... your cooling the "environment" as opposed to just cooling a piece in the environment. The glovebox will cool back down at the same rate which will reduce/remove the condensate upon reheating.

Good work by the way!

Originally Posted by xBrady

I can't remember who it was (must have been at least 9 months ago), but someone did this in a very ghetto fashion. They ran a thick plastic tube back to the back (yep right across everything)...

You rang? oh, and it was 14 months ago--feel old now?

Originally Posted by bergeron76

If your carputer is in the trunk, you could even create one in the rear of the vehicle. By using a fiberglass airscoop and putting in the trunk, you could pull air in and have your entire computer/cooling setup contained in the trunk. You'd have to create an output vent somewhere though.

See page 6 of the thread linked above. And I still have those scoops.

What the.... do you want to with Peltier, Ol33l ? A peltier needs twice the wattage it is meant to evacuate.

You want to cool a cpu outputing 30 w of heat, you'll have to use a 60W peltier, no less. And guess what, with this peltier, now you need to put 90W out of the computer.

Originally Posted by DeltaFX

What the.... do you want to with Peltier, Ol33l ? A peltier needs twice the wattage it is meant to evacuate.

You want to cool a cpu outputing 30 w of heat, you'll have to use a 60W peltier, no less. And guess what, with this peltier, now you need to put 90W out of the computer.

THATS DEFINITIVELY NOT THE BEST SOLUTION! thanx for getting those numbers for me DeltaFX, I had the thought that the peltier was going to consum some power, but not that much! I would need another PSU for the peltier, right? Im running with a M1-ATX.

WIZARDPC:

I saw your post some time ago when my proyect was just an idea... its great to still see you around as you seem to be the only one to have the system the same way I want to have it working... have you had any issues with water condensating in your pc?

Thanx

Originally Posted by justintime

Im being ignored!
Seriously though... when winter comes around, woudn't your HEAT start shooting down that same 'tube' or 'duct' or whatever you have placed next to the computer?

YES! Unless you make a switch off valve.

In regards to the duct running to the back of the car, how did passengers get in?

Originally Posted by eduardovdr

...I saw your post some time ago when my proyect was just an idea... its great to still see you around as you seem to be the only one to have the system the same way I want to have it working... have you had any issues with water condensating in your pc?

The AC ducting was a temporary solution. Cutting holes and putting vents underneath the car was the more permanant one, but we discovered very quickly that it created a vacuum and caused the PC to overheat while the car was in motion (if it was parked, it was fine).

Originally Posted by Cœur d'Arcy

In regards to the duct running to the back of the car, how did passengers get in?

Passengers? who would want to ride in a ghetto fabulous setup like that?

The ductwork was flexible so I moved it the ONE time someone rode with me when it was in there.

Originally Posted by dmcdlrn

Ok, I just talked to my dad... he worked for 20 years designing refrigeration systems for high and low temperature environments... We all are right... The AC is dried because the hot air from the car condenses on the evaporator in the heater/evaporator core... which is then dripped out the bottom of the car like we said. The air is then dry (also because its cold it naturally can hold less mosture then warm air) blowing it onto the computer would be completely safe as there is no moisture to leave behind on the board... the problem arrives when you shut the car off and remove the ac... The computer is then not the same temperature as the ambient environment... some of the board will be much cooler, and the hotter parts may be closer to the ambient temperature, but the warm air from around the car which was previously blocked by the "blanket" of cold air from the ac duct then moves in and condenses on the colder surface causing much damage.

The above is correct. Condensation in the open-air occurs when the relative humidity nears 100%. Relative humidity, as one would expect, is relative to temperature, not the absolute water content in the air. Additionally, the amount of water that air can "hold" is proportional to the temperature -- warmer air can hold much more moisture than colder air. So, you could have 100% relative humidity at 20 degrees F, and 100% relative humidity at 75 degrees F. Though both are 100% RH, there is MUCH more moisture in the air at 75 degrees than 20 degrees. Therefore, it's often more useful to refer to the dewpoint temperature, which is the temperature at which the air becomes saturated (100% RH). The dewpoint is always less than or equal to the temperature. For example, a dewpoint of 70 is what many would call humid, while a dewpoint of 20 represents dry air. Therefore, when air cools in the AC system (say, air going through the AC system cools to 40 degrees), moisture is also removed, since the dewpoint of the air coming out of the AC vents MUST be equal to or less than the temperature (40 degrees in this case). So, on a humid day with dewpoints above 60F, in order for cool the air to 45 degrees for air conditioning, a lot of moisture is removed from the ambient air -- thus the reason why you see the puddles of water under your car after running AC. For a surface, such as a motherboard, condensation would occur when the dewpoint is greater than or equal to the temperature of the surface. For example, if your motherboard was 75 degrees, and you were pumping air with an 80 degree dewpoint onto the motherboard, the water vapor would condense onto the motherboard -- bad! That said, many computer electronics will run at least 100F. This means that, in order to attain condensation on the parts, you'd need to pump in air that has a dewpoint of 100F or greater, which you will not find unless you're in a geyser.

And actually, pumping AC air (with low dewpoints) across the components will, in many cases in the US during the warmer months, result in less water vapor moving across the components, and a lesser chance of condensation. For example, take a typically humid day in the central or eastern US, with dewpoints in the 60s and 70s. Air coming from the AC system would have dewpoints in the 40s most likely, assuming that your AC works. So, you can either use your fan to circulate high-moisture air across the components, or use the much drier AC air.

It should be noted that the AC air will also cool the non-heated surfaces (e.g. computer case, etc). There is a chance that the case could cool to the temperature of the AC air (usually 40s), which means that you could have some condensation on the case. However, I can't imagine that this would be a likely scenario, since many CPUs and hard drives run upwards of 90 degrees, and thus the case would likely be heated enough to avoid this potential issue.

I just had to explain this a bit, since I am a meteorologist afterall. I'm still in the research phase for my first carputer,however.