It takes from 30 minutes to 1 hour to fully recharge your cars battery when driving so you do need to drive a minimum of 30 minutes at highway speeds for your battery to get enough charge into it before shutting the engine off.
If possible drive for 30 minutes and then if you need to stop let the engine idle while someone watches the vehicle and then drive it again for another 30 minutes and the battery should be fully charged back up if the battery is good.