Long Term Usage

Hey, I am planning on incorporating my Arduino AT-Mega 2560 into a home security system, and I was wondering how reliable would this be, it will be in a protected steel casing with an interference shield at a room temperature of roughly 16 degrees, anyone know or could help me by taking an estimation of how long an arduino in these condtions would last?

I should also add what the board will be powering.
In terms of that, it won't really be powering anything apart from a few LED's with 270ohm resistors and an LCD 16x2 display, it will also have an Ethernet shield to where it will be controlled by an interface hosted on a Raspberry Pi. All of the other I/O's will just be inputs from sensors which will obtain their power externally.

As for the power supply, it will be running with true DC from a 12V battery.

-Regards

The weakest link is probably the voltage regulator. If you're not giving it too much power to dissipate, it should be pretty much bullet proof.

It will be running on a steady 12V true DC from a battery. I've updated the OP with more information.

Also could you give me a rough estimation of how many years? This may be a large target, but my target is atleast 8 or so years.

If it's having to deal with 12v Input, I still wouldn't trust the voltage regulator on a long term basis. I'd suggest using an external 7805 chip in it's place. The cost would be peanuts compared to the extra reliability.

Alright, i'll take that into account on building, cheers!

16 degrees

American degrees or European degrees? :wink: Electrolytic capacitors and batteries can have trouble below freezing, and if you get condensation, that can cause trouble too.

Otherwise solid state electronics pretty-much "last forever" with failures being almost random... The likelihood of a failure in the 6th month is about the same as the 60th month. Early failures are a little more likely, and as the device ages the failure rate goes up a little.

This is from [u]Atmel[/u] and it only applies to the Amel ATmega chip. The more components you add, the higher the chance of a failure:

Mean Time Between Failures is an indication of the number of hours to pass between failures.

Please find below the predicted MTBF (Mean Time Between Failure) numbers of
our micro's at different temperatures. The statistical calculations are based
on current reliability qualification data in the "microcontroller
reliability data package".

Atmel has been shipping NVM parts for 20 years and Flash Micro's for 13
years. We have never experienced a long term reliability problem.

Here are the MTBF numbers calculated from life test and data retention
results:

65ºC 1.69x10e7 hours. => 1929 years
85ºC 4.46x10e6 hours. => 509 years
105ºC 1.34x10e6 hours. => 153 years

I built a car alarm for my 1994 van almost 20 years ago (with a different microcontroller), and it's still running. It runs 24/7 whither armed or not, and the only time it gets re-booted is when the car battery dies every 3 or 4 years. It's built on a breadboard and it's exposed to California temperature variations (occasional freezing and occasional hot days).

I think it was 2 years ago, I built a sound-activated lighting controller with the Arduino to work with the "mood lights" in ceiling of the van. The Arduino is only "powering" some LEDs and solid state relays and I'm using the Arduino's built-in regulator off the 12V supply. (The other electronics don't use the Arduino's regulator).