The sat-nms LFTX/RX real time clock is backed up by a gold-cap capacitor. The gold cap supplies the RTC chip with power for several days if the main power is missing. This is the preferred mode of RTC backup for stationary installations of the LFTX/RX.
For applications where the sat-nms LFTX/RX is powered up only occasionally, a lithium cell may be connected inside the chassis in order to provide a permanent buffering of the clock.