Controllers have a backup battery to maintain the real-time clock, a control strategy's Autorun flag, and a strategy's persistent variables. With the exception of older SNAP-PAC-S1 controllers, the above listed controllers have a soldered, 3.0 VDC lithium battery and is not user serviceable. (Older SNAP-PAC-S1 controllers use a replaceable 3.6 VDC battery, Opto 22 part number G4BATT32.) For more information about the type of Backup battery in your controller, refer to your controller's data sheet.
This OptoKB article describes how to determine if a controller's soldered, coin cell battery needs replacement.
When the battery fails, the following may occur but all symptoms may not be apparent:
- The real-time clock has the incorrect date and time.
- A control strategy does not automatically start upon reset or power-up because the AutoRun flag is disabled.
- Persistent values disappear.
If the above symptoms are suspected, test the controller by performing the following:
- Use the PAC Terminal utility to set the Autorun flag. From the utility, highlight the controller name and select View>Status. Select the Autorun enabled option.
- Synchronize the controller real-time clock to the PC time. From PAC Terminal or ioTerminal, highlight the controller name and select View>Status. Select the Sync time to PC button.
- Turn off the controller for approximately 15 minutes.
- Power up the controller and notice if the above listed Symptoms appear. If they do, the battery is dead.
Measuring the voltage across the battery is also an indicator.
- Remove the screws and top cover from the controller.
- Slide the internal boards out of the controller.
- Separate the “I/O board”, the board with the mounting rack connector, from the set of boards. This exposes the circular coin cell battery.
- Measure the voltage across the battery. If it measures 2.8 VDC or lower, the battery is failing or has failed.
When battery replacement is necessary, contact Opto 22 Product Support to set up an RMA to send in the controller for servicing.
FACTORS AFFECTING BATTERY LIFE
The battery normally has a 5-year life cycle, but other factors may affect a battery’s service time.
Storing the unit with the power turned off shortens the battery lifespan. The battery is actively backing up RAM during this time.
Warmer temperatures degrade the battery life cycle.