Q: will a bad battery keep vehicle from running once started?

If the charging system is not functioning, the vehicle will definitely not run if the battery voltage is too low. Even if the charging system is functioning, there are conditions under which a dead battery will cause the car to stall those conditions including an internal short in the battery. It’s possible to damage the alternator trying to charge, or re-charge, a dead battery and consequently the best thing always is to have the battery load tested and replaced if indicated by the test.

Once you have a fully charged battery installed, that passes a load test, charging system output should be verified against factory specifications as the alternator may have failed thus perhaps causing the battery to die. It is also possible that a failed or loose serpentine belt is not properly driving the alternator. To have the alternator inspected and replaced, if necessary, please request an alternator inspection/replacement and the responding certified mechanic from YourMechanic will get this resolved for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.