The M3 shuts down the +5v line to the PC completely if the battery voltage dips below 7v while in operation, or won't start the pc at all if the battery voltage is below 11.2v (had this happen with the stock car battery). The cut offs are not adjustable on the M3 but they are on the M4. Otherwise you'll want to go with an Opus or one of the more full-featured power supplies in the mp3car.com store.
or make your own shutdown circuit like im doing as soon as i can find free time. 11.2 is awfully dead for a car battery.. you sure wont be starting your engine.
HDD's are more sensitive to rapid temperature changes as much as absolute temps.. never had a drive cold enough to freeze the spindle! Wow -40 you guys are so 'hardy'. I have had an array of WD 3.5" HDD's run several years at 40 to 34F would get down to 15F or so before start up... never a problem. Biggest problem I've had with HDD's and temperature change is the breather hole. Seal it and expansion/pressure can be a problem, otherwise temp changes can lead to condensation and that can be a real killer.. also grows fungus & mold which can cause electrical problems.
But if you think about the head flying microns over a spinning disk and ensuring that the metals in mounts & head etc all expand and contract properly so that the flying head maintains proper flight (LET ALONE the data area dimensions & reading & writing) If you read the specifications on HDD's - some can be as sensitive as not allowing more than 1 degree centigrade temperature change per hour !
I'm new to mobile computing (other than laptop), however have produced many sealed (very close to hermetic) electronic enclosures(up to 300W) I've been dropping in on MP3car for a while now.. thought I'd join... (just got a Lilliput from MP3car for my truck)
Where I need help is trying to solve is WHERE to put the computer in the vehicle for best heat dissipation (NO FAN)... the floor gets hot in many areas... and I really hate cutting into the carpet.. the dash is too stuffed & congested..
I'm thinking the doors ? (maybe that's why engine computers were there (especially hot 1st gen).. Gets good airflow (over outside) and can radiate over large area too ? Problem is all the mechanical 'stuff' for window & door lock etc..
ANY IDEAS ?
After the USB devices, what else is there? If you're hibernating then all the RAM has been written to disk and the computer is shut down already. And if you're using Sleep mode then it keeps the RAM powered so it doesn't have to pull the information from the hard drive on wake, that's it. So basically if you're shutting down power to the USB devices, the computer isn't using any other power.
Originally Posted by trader007
its so i can run the computer while the engine is off and i wont have to worry about anything. i still havent got the controller built- my first attempt failed because i put the transistors on backwards. no time to do it, itll get done eventually. not a big deal right now as i dont sit outside in my truck with this freezing weather weve had.
Originally Posted by Maheriano
I lurked for a long time too, good to get in the game. I'm betting that early engine controllers didn't have the benefit of modern heatsink design. I installed in the dash and didn't have any heat issues early on. Others here have tried mounting everywhere from the steering wheel to the trunk with variable results. I am personally leaning toward remounting my dash install under my glove box. More accessible there.
Originally Posted by Goofy_Brained
:P im pretty sure there is nothing modern about any heatsink... theyve been around since the wheel. the way computers are internally made has gotten better though, they have always been tough but now more then ever they are virtually invincible under many conditions because they use high temp high shock resistant parts inside.
Originally Posted by gerradbail
under the glovebox would be ok if its small enough case, i think the trunk is best for most cars though. cops put them in the trunk too, for many reasons. i have a truck, so there is no trunk but luckily the rear side jumpseats actually fit an mATX mainboard perfectly.
Thanks Maheriano & Trader for the replies. Been reading other installs on MP3car... good stuff.
I've got a truck - but most good spots on floor are too hot for fanless system (engine heat stream, exhaust, cat converter & trans underneath). Glove too small. Planning same as my servers - uITX format, but when add PS, HD, sealed connectors the Ststeel enclosure grows to 9x12x2.5.
Thought about roof (sunlight probably issue).. now kinda looking at back door of quad cab - probably make a mold for door & pound or pour metal for attach & then use liquid sink.
P.S. There are so many ways to 'sink' heat out of devices .. and I am still amazed at the number of NEW ways engineers and DIY'ers have found to improve heat transfer. Good thermal management is the only path to reliability in electronic equipment.
Specs rule for longevity on rotating HDD's. If you are going for a year or maybe two - you can violate - at your data's risk and probably win. I have pushed the spec limits & lost many (pushed to limit though) But now have about every sized carcass for designing mounts though :second: Some kind of heating is required to speed up start & to save the wear on the bearing with a cold weather start (I have used an eyepiece heater ~2.7 x 7 inches - 12V - works great). Heaters in auto are an issue with energy waste and with battery drain OR you have to wait for temperature to transition at HDD's safe rate to safe operating temps.. the delay !
I have decided to abandon rotating HDD & save my pennies for extreme INTEL SSD (also need the speed for eventual USRP addon) but the specified 'operating' low temps are not good enough (YET) - storage to -50 C.. but given say a -40C cold soak, and given fast transition temps on SSD, then it should be pretty easy to use with a quick heater (Resister & bang-bang fan controller) - probably triggered by ignition or keyless entry. Should be much faster than slow heating with rot HDD. Industrial SSD's are good to -40 operational.. but cost $4K !
A while ago, tried the OCZ (Solid series) for a rugged DC server (but only good to -10C). But with a hermetic sealed box, I like to load OPSYS over network and had trouble with PIXIE & OCZ SSD controller playing nice (failure type problem with BIOS on three diff mfr's MB's) whereas Intel SSD worked but was only good to 0 C low temp operating range). Of course USB Stick is always possible (but takes lot more work to get USB location & drivers into opsys preboot - becomes very box specific. I want to network to any/all the boxes in truck and upgrade/rework.
Sorry.. rambled a bit... :lol:
@G_B - Sounds impressive. I've just lost a motherboard to frost in the dash and I'm pushing forward with an upgrade. I was looking a new enclosure from mini-box, but then stumbled on these. Imagine: Center console mounted with a 4 sec boot and running Android 2. Could be sick.
Itronix sells HDD heaters for $310
HDD KIT 80 GB HARD DISK DRIVE WITH HEATER (Duo-Touch II)
Product: Duo-Touch II
Category: Storage Drive and Media Accessories
Upgrade the standard hard drive for your Duo Touch II to a 80GB hard drive with heater. A hard drive heater is needed if you are working in extremely cold climates. Boot temperature 0° C without Hard Drive Heater; -20° C with Hard Drive Heater.
Weight: No Weight Available
Part Number: 62-0725-003R
At -25C to -40C few month in a row, it is really annoying to have all this temp glitches. Solution could be to use some microcontroller and extra 4A*h accum to constantly feed HDD (1.7W typical idle power) overnigth, turn off CarPC (keeping in mind one can not heat it faster than 20C/hour to avoid data loss even in powered-off state), or have a terrarium pad and a controller to keep CarPC internal temp at 0C. I believe sooner or later it will be addressed by mini-box, carnetix, opus whatever DC power units, because it is impractical to have automotive supply, not capable of dealing with weather outside of SF Bay Area.