To guarantee 30 minutes of battery power in case of dual generator failure, the battery amps on takeoff must be:

To ensure that the battery can provide at least 30 minutes of power during a situation where both generators have failed, the appropriate choice involves understanding the relationship between the battery capacity and the required load in amps.

The power consumed is directly related to the amperage draw; thus, to maintain operation for a designated period, it is crucial to keep the current draw low enough. The limit of battery amps during takeoff needs to be set such that, if the generators fail, the battery can still support the necessary systems without depletion.

If the battery is limited to below 10 amps, this allows for more efficient energy use, ultimately extending the time the battery can run before depletion. It balances the consumption of power versus the stored energy in the battery, ensuring that the battery can sustain the essential systems for a full half hour.

This threshold is calculated to allow the battery to last through critical phases of flight where generator failure may pose a safety risk, ensuring systems remain operational without a sudden loss of power.