Skip the auto shop - Our mechanics make house calls

Q: Alternator not charging battery

asked by on

Have put 2alternator on already still not charging battery when turn the key off volts go up go down when turned on was wondering if ignition lock cylinder may cause this problem

My car has 200000 miles.
My car has an automatic transmission.

This may be related to what is called a voltage regulator which is a unit that regulates the charging of the battery by the alternator. When this is not working properly, this may cause the alternator to be over charged or under charged. Its job is to maintain the correct amperage from the alternator to the battery. I would recommend having an expert from YourMechanic come to your location to diagnose your charging system.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

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: windshield wiper motor

Generally, if the same electrical component fails multiple times, there may be an electrical issue. There can be a broken or loose wire in the wiper circuit. It can be causing an intermittent short or over-voltage situation to the wiper...

Q: Where is the fuel pump relay located on the 2000 Lexus GS 300

The fuel pump on this vehicle has a relay in the engine compartment main fuse box labeled EFI fuse. The fuel pump is controlled by an fuel module in the left rear of trunk and this is powered by this...

Q: Groaning / binding noise when turning the wheels. I put on a used power steering pump from wrecking yard and the sound still is present.

Hi there. The noises that admit when the power steering is moving is the pump. The other parts will not make any noise except for a water swishing noise as the fluid moves from side to side in the steering...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
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 Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.