If your vehicle has continuous current on the cigarette lighter, you can set how far the vehicle battery can be discharged on the cool box. I don't know if it's enough for the whole day. You should also consider the temperature inside the vehicle when it is parked in the sun to see whether the independent cooling is still sufficient.

There is no battery function. It only runs when it is plugged in. This means that as soon as you switch off the car, it is switched off and no longer cools.

If you use cooling elements, the contents will stay cool and fresh all day long. You can also do without cooling elements, but the items may stay 5 degrees cooler - depending on what you have inside.