During Exchange today, I had lots of conversations about the best way to know if a power module is getting low and should be replaced.
We HIGHLY reccomend NOT tracking battery voltage and setting alerts. First, the voltage curve is not linear - its fairly flat until the very end when it drops quickly. Second, each device uses a different about of power, so the alert levels are device dependent.
There are two alerts sent for Emerson Smart Wireless Devices - a warning, which indicates that the power module should be replaced soon and a Critical alert, which means that it should be changed immediately. For the Rosemount Wireless products, a device will stop reading the sensor on a critical alert; however, it will keep transmitting data for the rest of the mesh.
If you are mapping for OPC/ Modbus:
Rosemount, Vibration, Analytical Devices:
Low Warning alert tag: POWER_SUPPLY_CONDITIONS_OUT_OF_RANGE (Boolean)
Critical Alert: CRITICAL_POWER_FAILURE (Boolean)
Fisher 4300 Series:
Low Warning Alert: BATTERY_WARNING_GETTING_LOW
Critical Alert: CRITICAL_POWER_FAILURE
These alerts are easy to use and provide a better indication of power module status.
If you want to see how long your power module is expected to last, there is a free online tool:
www.emersonprocess.com/smartwireless under "Getting Started With Wireless"
If you need a quick Power Module replacment, the Rosemount online store has them! Available for 3 day shipment with credit card order!
http://store.rosemount.com/