Skip the auto shop - Our mechanics make house calls

Q: Battery voltage is low.

asked by on

put new alternator in, now battery gauge went from like 16 to 9, also serpetine belt is NOT put on tightly charging system?

My car has 218000 miles.
My car has an automatic transmission.

A: Hello. If the battery voltage reads low on...

Hello. If the battery voltage reads low on the gauge then that is a sign that the charging system is not functioning correctly. If the alternator is brand new then there is little chance that it is the source of the issue. More likely then that, is the loose belt. The alternator functions using the serpentine belt to turn the pulley and generate power. If the belt is loose then the pulley may not be turning properly, which could potentially be causing your low voltage reading. It may be possible that the belt is worn, that the tensioner is bad, or that the belt was routed incorrectly when it was installed. I would take a careful look at the drive belt system, and verify that it is routed correctly. If everything looks okay, I would recommend having a professional technician, such as one from YourMechanic, come to your location to (determine if it is the tensioner that needs to be replaced](https://www.yourmechanic.com/services/drive-belt-tensioner-replacement) or if there is another issue present.

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

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: Engine clicking and shaking

Hello, thank you for writing in. Due to the timing being relatable to the oil change, you will want to start by double checking the repair. Make sure your oil filter was installed correctly and is allowing the oil to...

Q: I installed a new fuel pump, but the line from the pump to the carb is leaking at the flare fitting on the pump

Hello, thank you for writing in. The hardest part is done. Locating and noticing the leak is typically where people fail to follow through with their repairs. The flare on the line was likely bent or damaged. They are very...

Q: Problems with various electrical functions after replacing the battery....

Hello, thank you for writing in. The vehicle is likely having an issue with the charging system. This may mean there is an issue with the alternator, or the connections to the battery. You will want to do a full...

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...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.