If the battery is changed, that will mean that the BIOS was set back to january 1 1980.
Go into BIOS, set the clock to the correct time.
For DELL 370 precision , here is the BIOS instruction:
Replacing the Battery
CAUTION: Before you begin any of the procedures in this section, follow the safety instructions located in the Product Information Guide.
To prevent static damage to components inside your computer, discharge static electricity from your body before you touch any of your computer's electronic components. You can do so by touching an unpainted metal surface on the computer.
A coin-cell battery maintains computer configuration, date, and time information. The battery can last several years.
The battery may need replacing if you have repeatedly reset the time and date information after turning on the computer or if one of the following messages appear:
Time-of-day not set - please run SETUP program
Invalid configuration information -
please run SETUP program
Strike the F1 key to continue,
F2 to run the setup utility
To determine whether you need to replace the battery, reenter the time and date in system setup and exit the program to save the information. Turn off your computer and disconnect it from the electrical outlet for a few hours; then reconnect the computer, turn it on, and enter system setup. If the date and time are not correct in system setup, replace the battery.
You can operate your computer without a battery; however, without a battery, the configuration information is erased if the computer is turned off or unplugged from the electrical outlet. In this case, you must enter system setup and reset the configuration options.