Any JACE controller with a charged backup battery holds a key advantage over a battery-less SRAM-equipped JACE. The advantage is that station operation continues (uninterrupted) across very short power outages, that is “power bumps” lasting only a few seconds—without initiating an orderly shutdown. A UPS could be used to mitigate this, but this would re-introduce battery maintenance for the UPS.
The NiMH battery provides enough power for this, immediately recharging when power is restored. If a power outage lasts longer than its defined “shutdown delay” time, the NiMH battery allows sufficient time for the JACE to perform an “orderly shutdown”, including saving the station’s database (config.bog) and all recorded alarm and history records.
However, the JACE without SRAM but with a weak NiMH battery is exposed to a different power outage issue—where the potential exists for data loss (since the last station save), due to insufficient battery power to complete an orderly shutdown. Potentially, this could also occur if enough power outages occur in rapid succession—draining the controller’s battery to a low level.
A battery-less JACE solves that problem, as all station-generated data (changed from that stored in its non-volatile flash memory at the time of power loss) is always preserved in SRAM. Upon power restoration, this data is “played back” in the station during startup, then saved in its non-volatile flash memory.
Please note that if the JACE power event occurs when station users have unsaved file changes, say in a Px file or Nav file being edited, those unsaved changes are lost. This behavior may seem different from a battery-equipped JACE entering an ordered shutdown—but it is not.
The practical difference is that a battery-equipped JACE may keep running over a short “power bump”. Station users may be aware of such an event, and react by saving changes (click Save button in the active view). Providing that communications are still established, the file edited may be saved. Or, power may be lost only momentarily, and then remain stable until the user does a normal save.