Another choice you have would be to store the hour count to the serial EEPROM less often. I have built similar functionality into a microcontroller product. I saved into a 93C46 once every 10 minutes and anticipated a statistical life time of about 10 years. To make a 10 minute store work you must implement a power supply with early warning shutdown status and enough capacitor charge storage that the system can save any residual count since the last 10 minute save to the EEPROM before shutting down. It is my opinion that building a power supply capability like this is relatively easy if the hour meter function is all the microcontroller is doing. If you are running motors, relays, or other high current loads off the same supply then it is a bit more work since the early warning system should include a capability to shut down these high current loads.

As with any serial EEPROM storage system it is advisable to store dual copies of the data, each with a check code, to provide for reliable recovery of data when the next power up occurs. You can look in these postings for more discussion on reliable storage of EEPROM data...

http://www.8052.com/forum/read.phtml?id=30678
http://www.8052.com/forum/read.phtml?id=50185


Michael Karas