Q: I replaced the alternator about 6 months ago. Yesterday while idling the battery light popped on and my car quit.

asked by on

After replacing the battery and alternator the battery light pops back on after being cranked for a couple mins. The car seems to be running fine however, there seems to be no power with things. The windows are extremely slow and so are the windshield wipers. What could possibly be the problem?

My car has 85000 miles.
My car has an automatic transmission.

This may suggest a failing voltage regulator. The voltage regulator is a unit that regulates the charging of the battery by the alternator. When the voltage regulator is not working properly, this may result in the alternator allowing too much power to be delivered to the battery resulting in damaging wires and prematurely sometimes destroying the battery. A common sign of this is usually the acid inside the battery boiling causing the battery to swell. In other cases it may result in the alternator not supplying enough power to the battery, resulting in undercharging the battery or not charging it at all as in your case. I would recommend having an expert from YourMechanic come to your location to diagnose your vehicle’s charging system.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. I replaced the alternator about 6 months ago. Yesterday while idling the battery light popped on and my car quit.

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Battery is drained in the morning - 2010 Mercedes-Benz C300

Hello. You have either a faulty battery (a load test on battery can easily determine status of battery), faulty charging system, and/or a substantial phantom load (parasitic power draw) that is discharging the battery while the vehicle is turned off....

Q: Problem with intake manifold

Hi. This trouble code occurs in sync with a ticking noise within the circuit. If the manifold has lose bolts or was not put together correctly after maintenance this can be the result of the code. I would recommend having...

Q: How do I drain the RamBox side storage units?

The RamBox side storage units are waterproof, but they have a drain in case you want to wash them out. To drain the side storage units, just lift the edge of the plug at the bottom of the storage unit....

Related articles

P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...