Auxiliary power
The auxiliary power capacitor is an alternative power source built into all modern controllers which permits the unit to perform certain tasks, such as self-maintenance, for a short time after being shut down. As of Companion 8.4 (ATOS/CX 12.1), units that include this capacitor can control its settings. Along with the new distress beacon, which is also powered by the auxiliary capacitor, these features comprise the emergency power system.

Accessing the emergency power system

Auxiliary power control can be found under the manage > EPS menu, or with the aux command. The relevant menu items are as follows:

EPSToggles the availability of auxiliary power when the unit is off.
radioToggles the availability of radio (incoming and outgoing SMS) when the unit is off.
videoToggles the availability of video (vision) when the unit is off.
audioToggles the availability of audio input (hearing) when the unit is off.
GPSToggles the availability of GPS connectivity when the unit is off.

The other items in the EPS menu pertain to the distress beacon.

Additionally, auxiliary power always provides limited motor control, which is adequate for the unit to touch itself and perform basic tasks such as swapping out power cells. The amount of power used by these subsystems is identical to that used by them when powered on, as described in the subsystems management section (values may vary for third-party chassis.) Radio back-up consists of both the receiver and transmitter subsystems.

The auxiliary power capacitor stores 240 kJ of power, which is replenished from the main battery while the unit is powered on at the rate of 10 kW. Owners of ATOS-enabled units must be mindful to ensure that this recharging process does not cause overheating if it occurs simultaneously with shield and FTL capacitor recharging.

Changes from earlier versions

Previously (Companion 8.3.11 and earlier), the capacitor was used only to provide limited motor control, i.e. the amount necessary to allow the unit to touch itself. This resulted in very low power usage and enabled most models to maintain indefinite offline power for motor control at the expense of greatly limited versatility. With the 8.4 design, running out of auxiliary power leaves the unit completely stranded, although if main power is not depleted, it may still attempt to power on with the @boot self-command.