Hawaiʻi outage planning

Decide what needs power before the outage.

Build a short list of essential loads, choose how long you want to cover them, and size the battery from that plan.

HIEMA recommends preparing for power outages and maintaining two weeks of household supplies because damage to ports, utilities, or other infrastructure can disrupt normal access to essentials.

Start small

Cover the loads that matter first.

A useful first list is refrigeration, communications, phone charging, basic lighting, and fans. Portable air conditioning can increase battery and inverter requirements quickly, so include it only if it is part of your actual outage plan.

FoodSafety.gov says an unopened refrigerator generally keeps food cold for about four hours. A full freezer can hold temperature for about 48 hours, or about 24 hours if half full.

Medical equipment

Use device-specific guidance.

For powered medical equipment, a general battery calculator should not be your only plan. FDA guidance recommends checking the device instructions and contacting the manufacturer or distributor about backup batteries or generator compatibility.

Keep emergency contacts and backup arrangements that do not depend on this estimate alone.

Official guidance

Sources used for this page

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