Thanks for information which will undoubtly be handy for US customers 'in the zone'
We have learned ( at times the hard way) that a smartphone can go from 'nice to have, to 'need to have' in a heartbeat, especially when nature threatens. Our power networks here in the Islands aren't quite as resilient & robust at the best of times, thus it migh be time to suggest that other than battery powered flashlights and radios, the smartphone(s) should be kept as near fully charged as practicable, as one simply cannot predict the duration & timing of any power interruption / blackout situation. 'PowerBrick' storage batteries to recharge devices should also be kept 'topped off' to be ready if & when needed.
As a related side issue, old thinking mostly driven by landline dominated communication can still be important as landline ( copper/ fibre) usually supplies most modems & routers which generate our wifi. After a catastrophe, cell tower structure can rebuild and adjust much more quickly as all area towers aren't usually put out of service in the manner which pole based phone wires can be toppled and destroyed by winds. So even though delicate, the old addage about communication being the first thing to go, and the last to return, just isn't true anymore - as long as one has actively taken precautions.