Hello and welcome to Pearl/Just answer.com, Super mechanic here. I will do my best to help you with your question. My goal is to help save you money and I hope you will be completely satisfied with my answer. If you need any more on it just let me know.
About your vehicle.
That sounds like a charging system problem, (alternator), and if the battery is fully charged, then the drive would not be a problem. Each battery is rated at an hourly rate that it will be able to run the vehicle, in the event that the charging system does not work.