My question relates to the reliability of low-cost accelerometers (MMA7455,ADXL345 etc.) in commercial products with a expected life expectancy of 5 years or more. The tilt angle reading from the accelerometer will be used as a feedback parameter to orient a single-axis plate-reflector positioning mechanism. From testing, I gather that the tilt sensitivity of both accelerometers are coarse but this doesn't really affect my positioning accuracy that much. So, sensitivity isn't a big issue. The accelerometer is placed in a IP65 box to protect from external weather conditions. The box is always shaded by the reflector plates are is not directly exposed to weather per say. Temperatures can vary between +15 degrees Celsius to +45 degrees Celsius. I use I2C bus protocols to communicate with the accelerometers. Price: These accelerometers cost around $5. I am willing to spend upto $30 because service costs can dig a hole into my budget. ADXL103/203 seems to be a good alternative but then shipping costs to my country cost more than the product itself! My second query- Redundancy in engineering design: I have yet to come-up with an alternative in-case the accelerometer fails. Maybe using 2 accelerometers would do the trick? Please advice.