Choose by charging port, location and the energy you need.
A charged power bank works away from the car until its stored energy runs out.
It converts the vehicle supply into AC. It does not store energy.
An AC-only charger may need an inverter. USB-C charging requires compatible power output and cable.
Include cables, battery wear and vehicle energy use, alongside the purchase price.
Stay within both ratings. For longer use, run the engine only in a ventilated outdoor area.
Use vehicle charging on the journey and portable USB backup after leaving the car.