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P a g e
Battery
FMGuard contains an internal Li-Ion battery for operation even, when the external power is
absent making it possible to report power loss. Please note that when the external power is
removed, the device will power down by default. This setting is can be changed on the LCD
settings.
The analog outputs will automatically stop working when power failure occurs, the internal
battery is not enough to power up or supply the voltage needed.
The battery charging is automatically by the system, leaving no need for user interaction.
The battery cycle (numbers of charges and discharges) also influences capacity. After 300
cycles the capacity has dropped to approximately 80% of initial capacity. Lifetime of the Lithium
coin-cell in this state is 6+ years.
External Li-Ion Battery (Optional)
External battery connection is possible on the terminal block connectors on the top side.
Jumpers located on the back side of the device is used to switch between the internal and
external battery.
Note:
Only Lithium Ion batteries (3.7V nominal) are allowed as external battery, and both
battery switching jumpers (jumper 1 and jumper 2) must be moved together. Mixing the jumpers
in different positions may cause abnormal operation, and in worst case damage the
battery/device.
Battery Selection Jumpers
Jumper Position Used Battery
1
1-2
External battery (NTC temperature
sensor)
2-3
Internal battery (NTC temperature
sensor, default)
2
1-2
External battery (positive terminal)
2-3
Internal battery (positive terminal,
default)
Jumper 1
Jumper 2
1 2 3