almoniyot

Was driving home from work last night and warning light came on that battery voltage was low (no previous signs of problems - car started right up that day with no difficulty). Once I arrived home and shut the car down, it would not start after 5 minutes. Alternator? Battery?

Rocky-in-Connecticut

battery. usually. Autozone can check battery for free

4Driver4

What does the gauge read with the car running?

Usually a dying battery means that the car turns over weakly or won't start in the morning, but once jump started and driven a bit it will start normally. If the starts OK in the morning but won't restart the same way after driving it usually means the alternator is dying.

Battery light on while driving almost always means there is a charging problem.

thomas1978

experience the same sympthoms. Just never seen the battery light (yet?).

S4_Cinci (I S'edTFA)

foolproof, but rather a clue to further investigate. The alternator should put out volatages in the 13.7V range or higher while the car is running. sometimes the meter in the car isn't always the best way to monitor subtle changes.

Also remember that while a bad alternator can kill a good battery, it is also possible for a bad battery to kill an alternator by calling for too much current/voltage in an attempt to charge it. There has been a lot of discussion on this in this forum in the past. If you suspect problems, get it checked out sooner rather than later - an electrical problem isn't going to cure itself and will likely leave you stranded if you ignore a warning sign!

4Driver4

My two scenarios are very general and should not be totally relied upon for diagnosis.

thomas1978

I'm still waiting for the thermostat and temp. sensor