SRAM plus battery scenarios

An SRAM-equipped controller can utilize both its SRAM and an installed backup battery, such as a JACE-6E or JACE-3E controller with an optional internal NiMH battery pack, or a JACE-2,-6,-7 controller (with SRAM option card) and its standard NiMH battery pack. This also applies to a QNX-based JACE controller with an external 12V sealed lead-acid battery, either as its main backup battery (JACE-603, JACE-645) or as a battery in “parallel” with its NiMH battery (JACE-7).

This hybrid “SRAM plus battery” configuration offers:

Immunity to power bumps, thanks to the backup battery—similar to a unit with backup battery only.
A longer allowable “Shutdown Delay” time, up to 10 minutes for a unit with only a NiMH backup battery. This is beyond the 30 seconds (recently 1 minute) maximum period. After continuous operation this long on battery power, at shutdown the JACE saves its database and powers off. So, a unit with a reasonably healthy NiMH backup battery could continue running over a power outage of up to 10 minutes. Note that the station’s “DataRecoveryService” must be enabled to specify this longer shutdown delay in station’s “PowerMonitorService”. If the unit is equipped with a sealed lead-acid (SLA) battery, this shutdown delay can be specified up to 15 minutes.
Data independence from backup battery condition, again a consequence of the ongoing SRAM operation. If the charge on the backup battery weakened such that the controller was unable to complete a database save on a controlled shutdown, or even if immunity to power bumps was lost, data integrity still remains. Upon reboot from a power restoration, the station’s DataRecoveryService restores (replays) the previously recorded station runtime data from SRAM.

Note a discharged battery could happen if multiple, consecutive power outages occurred, draining the charge on the rechargeable backup battery. A longer “Shutdown Delay” time could contribute to this. However, unlike with a controller not using SRAM, station runtime data is safe in this case.

Gain the features above by installing an optional NiMH battery pack in a standard JACE-6E or JACE-3E, or if another earlier model (e.g. JACE-2,-6,-7), by retaining its NiMH battery pack when installing the SRAM option card. By default, this hybrid configuration is standard with a “retrofit board” JACE-603 or JACE-645, assuming the controller’s 12V SLA battery (in the controller’s enclosure) is retained.

Note in this hybrid configuration, JACE monitoring of backup battery(ies) continues—so “battery bad” alarm notifications are still possible, and the regular replacement of backup batteries is still needed.

Again, the “SRAM plus battery” configuration for an SRAM-equipped controller is one of two possible configurations where SRAM is used: the other is for a JACE controller to be “battery-less”. See Battery-less JACE scenarios.

Although this hybrid configuration is typically the most desirable, note that some stations may be poor candidates for SRAM operation, with SRAM support even counter-productive. In this case, a controller platform that includes “built-in” SRAM (such as a JACE-6E or JACE-3E) can be configured to disable its DataRecoveryService, and use only its (optional) installed backup battery. Or, an SRAM option card can be removed from another JACE controller, such that it also uses only its installed backup battery. For more details, see Unsuitable station for SRAM support.