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.

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: 1995 f250 reverses fine but wont drive it still ingagues in gear but doesent move in 1 2 or drive

Hello there. Sometimes transmission linkage being misaligned can be the cause of this problem. In other cases, obstructions inside the hydraulic lines of the transmission or torque converter issues can cause problems like you've described as well. It is probably...

Q: What are the differences between distributor types for my truck?

Hi there. In 1987 Ford used a TFI (thick film integrated) module attached to the distributor housing, where timing is computer controlled, and a Dura-spark ignition module attached to the left inner fender, where timing is still mechanically and vacuum...

Q: Loss all power when driving.

What you describe sounds like a charging system failure. If the alternator isn't working, the car can run on the battery for a period of time, until the battery voltage gets below a certain point, usually around 10.5 volts. After...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
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.