But even the smallest four cylinder car engine is overkill...
This is true. The fuel used to overcome losses in friction is far greater than required simply to charge a phone. It's more efficient to charge the phone direct from the car battery, via a suitable voltage converter (e.g. a cigar lighter adapter).
... is overkill to charge a deep cycle battery because you are getting at least 60 amps out of the alternator.
This is false reasoning. The alternator provides whatever current is drawn from it by the item(s) connected. If nothing is connected then no current is drawn.
Frankly, all you need to get through a power outage is a stack of batteries and a suitable charger and inverter. The charger trickle-charges the batteries while you have mains power. When the mains power fails, you connect the batteries to the inverter and connect your equipment to that. Obviously the power and duration are limited by the ratings of the batteries and inverter; go as large as you can afford.
This is true. The fuel used to overcome losses in friction is far greater than required simply to charge a phone. It's more efficient to charge the phone direct from the car battery, via a suitable voltage converter (e.g. a cigar lighter adapter).
This is false reasoning. The alternator provides whatever current is drawn from it by the item(s) connected. If nothing is connected then no current is drawn.
Frankly, all you need to get through a power outage is a stack of batteries and a suitable charger and inverter. The charger trickle-charges the batteries while you have mains power. When the mains power fails, you connect the batteries to the inverter and connect your equipment to that. Obviously the power and duration are limited by the ratings of the batteries and inverter; go as large as you can afford.