2001 Nissan Sentra alternator

Happy to hear you understand it could leave you stranded, but when you have an intermittent problem like this, the generator is still working part of the time. The most common cause of intermittent generators is worn brushes. That's actually a mechanical thing, and as long as they work intermittently, you may get by for as much as days or weeks before the battery runs down too much to restart the engine. Once the "Battery" light turns on, about the most you'll get is around one hour of driving time before the engine stalls. You'll be driving strictly on the battery, so the less power you use, the longer the engine will run. Turn the heater and radio off, and anything else you don't need, like head lights in the daytime.