Most cell phone chargers are 5 to 9 volts DC, its very inefficient to convert 12-volts DC to 110-volts AC to use a wall charger to covert it back to 5-volts DC.


Better to get a car charger for your phone that steps down the 12-volts DC to 5-volts DC (or whatever voltage your phone uses to charge with)



Also you can find 12-volt powered AA battery chargers or solar battery chargers. Or convert (if you are electrically inclined) a 110-volt battery charger to run on 12-volts.


This way you are still doing the charging you need but without all the power loss that comes with an inverter.

I would still want an inverter for things you can’t run on 12-volts. But the demand for it can be much lower when you convert things to run on 12-volts.